Competitive Programming

Methods to Solve (2000-present)

Use these filters to narrow down your next problem to solve:

OJ: , Topic: , Quality: , Difficulty:

You can now sort these problems based on Distinct ACcepted Users (DACU) column.
Generally, problems with high DACU are the easier problems.
Note that we only update DACU column manually when we first entered the hint (thus an outdated data).

Column Point is only used in Kattis (and simulated in LeetCode) online judge.

All OJ Problem Title CP4+5 Hint DACU Point
13025 Fetching from uHunt 1.4a, One-Liner I/O giveaway, just print the one-line answer 0.0
carrots carrots 1.4a, One-Liner I/O just print P 15155 1.3
hello hello 1.4a, One-Liner I/O just print "Hello World!" 39217 1.2
lc2469 to replace with LeetCode link soon... 1.4a, One-Liner I/O simple C to K/F conversion 0 2.0
thelastproblem thelastproblem 1.4a, One-Liner I/O S can have space(s) 76 1.8
10071 Fetching from uHunt 1.4b, I/O + Sequences Only super simple: output 2*v*t 0.0
11614 Fetching from uHunt 1.4b, I/O + Sequences Only root of a quadratic equation 0.0
r2 r2 1.4b, I/O + Sequences Only just print 2*S-R1 14929 1.2
conteststruggles conteststruggles 1.4c, Selection Only, 2 Cases simple formula; check if answer in [0..100] 729 2.2
isithalloween isithalloween 1.4c, Selection Only, 2 Cases if-else; 2 cases 3761 1.3
laptopsticker laptopsticker 1.4c, Selection Only, 2 Cases if-else; 2 cases; note: one centimeter for both sides 3329 1.5
moscowdream moscowdream 1.4c, Selection Only, 2 Cases if-else; 2 cases; check n ≥ 3 3902 1.8
vajningsplikt vajningsplikt 1.4c, Selection Only, 2 Cases selection; multiple cases; be careful 788 2.1
grading grading 1.4d, Selection Only, 3+ Cases 6 cases 2744 1.5
lc2119 to replace with LeetCode link soon... 1.4d, Selection Only, 3+ Cases True if num is 0; otherwise True only if num is not divisible by 10 0 2.0
onechicken onechicken 1.4d, Selection Only, 3+ Cases 4 cases; piece vs pieces 6464 1.6
provincesandgold provincesandgold 1.4d, Selection Only, 3+ Cases 6 cases 4756 1.4
sith sith 1.4d, Selection Only, 3+ Cases 3 cases 1137 1.6
temperature temperature 1.4d, Selection Only, 3+ Cases 3 cases; derive formula 1776 2.2
testdrive testdrive 1.4d, Selection Only, 3+ Cases 4 cases 848 2.1
01124 Fetching from uHunt 1.4e, Repetition Only LA 2681 - SouthEasternEurope06; just echo/re-print the input again 0.0
11547 Fetching from uHunt 1.4e, Repetition Only a one liner O(1) solution exists 0.0
different different 1.4e, Repetition Only use abs function per test case 8964 2.3
lc1281 to replace with LeetCode link soon... 1.4e, Repetition Only break n into digits; do as asked 0 2.0
qaly qaly 1.4e, Repetition Only trivial loop 5955 1.2
tarifa tarifa 1.4e, Repetition Only one pass; array not needed 9768 1.3
timeloop timeloop 1.4e, Repetition Only just print 'num Abracadabra' N times 17170 1.3
11172 Fetching from uHunt 1.4f, Multiple TC + Selection very easy; one liner 0.0
12250 Fetching from uHunt 1.4f, Multiple TC + Selection LA 4995 - KualaLumpur10; if-else 0.0
12372 Fetching from uHunt 1.4f, Multiple TC + Selection just check if all L, W, H ≤ 20 0.0
eligibility eligibility 1.4f, Multiple TC + Selection 3 cases 1741 1.6
helpaphd helpaphd 1.4f, Multiple TC + Selection 2 cases 2044 1.6
leftbeehind leftbeehind 1.4f, Multiple TC + Selection 4 cases 2014 1.6
oddities oddities 1.4f, Multiple TC + Selection 2 cases 11523 1.3
12279 Fetching from uHunt 1.4g, Control Flow, Level 1 simple linear scan 0.0
lc1431 to replace with LeetCode link soon... 1.4g, Control Flow, Level 1 simple one pass check; leetcode-75 0 2.0
licensetolaunch licensetolaunch 1.4g, Control Flow, Level 1 easy linear pass 1969 1.4
11799 Fetching from uHunt 1.4h, Control Flow, Level 2 one linear scan; find max value 0.0
13130 Fetching from uHunt 1.4h, Control Flow, Level 2 simple 0.0
11364 Fetching from uHunt 1.4i, Control Flow, Level 3 linear scan to get l and r; answer = 2*(r-l) 0.0
11764 Fetching from uHunt 1.4i, Control Flow, Level 3 one linear scan to count high low jumps 0.0
lc2455 to replace with LeetCode link soon... 1.4i, Control Flow, Level 3 even and divisible by 3 means divisible by 6 0 2.0
oddgnome oddgnome 1.4i, Control Flow, Level 3 linear pass 2388 1.6
statistics statistics 1.4i, Control Flow, Level 3 one pass; array not needed 2942 1.7
11078 Fetching from uHunt 1.4j, Function one linear scan; max function 0.0
11332 Fetching from uHunt 1.4j, Function simple recursion 0.0
artichoke artichoke 1.4j, Function LA 7150 - WorldFinals Marrakech15; linear scan; probably one of the easiest WorldFinals problem; also available at UVa 0... 1390 2.8
digits digits 1.4j, Function direct simulation; also available at UVa 11687 - Digits 214 3.5
filip filip 1.4j, Function create a 'reverse string' function; then if-else check 6345 1.3
lc2180 to replace with LeetCode link soon... 1.4j, Function use sum-of-digits function 0 2.0
mia mia 1.4j, Function just if-else check 1136 2.1
01585 Fetching from uHunt 1.4k, 1D Array, Easier LA 3354 - Seoul05; very easy one pass algorithm 0.0
12015 Fetching from uHunt 1.4k, 1D Array, Easier traverse the list twice 0.0
acm acm 1.4k, 1D Array, Easier simple simulation; one pass 3526 1.5
cetiri cetiri 1.4k, 1D Array, Easier sort 3 number helps; 3 cases 1165 1.9
lc1491 to replace with LeetCode link soon... 1.4k, 1D Array, Easier (sum-max-min)/len; programming-skills 0 2.0
lineup lineup 1.4k, 1D Array, Easier sort ascending/descending and compare; or linear pass 3703 1.6
lostlineup lostlineup 1.4k, 1D Array, Easier simple 1D array manipulation 550 1.5
11349 Fetching from uHunt 1.4l, 2D Array, Easier use long long to avoid issues 0.0
hakkari hakkari 1.4l, 2D Array, Easier find indices of the '*' 659 1.3
lc1572 to replace with LeetCode link soon... 1.4l, 2D Array, Easier sum the diagonals; do not overcount the center cell for odd n; programming-skills 0 2.0
12658 Fetching from uHunt 1.4m, Easy character recognition check 0.0
12696 Fetching from uHunt 1.4m, Easy LA 6608 - Phuket 2013; easy problem 0.0
batterup batterup 1.4m, Easy easy one loop 4542 1.3
hangingout hangingout 1.4m, Easy simple loop 2218 1.3
hissingmicrophone hissingmicrophone 1.4m, Easy simple loop 7690 1.3
lc2739 to replace with LeetCode link soon... 1.4m, Easy simulate the process 0 2.0
stopwatch stopwatch 1.4m, Easy linear pass; simulation 390 1.3
11683 Fetching from uHunt 1.4n, Still Easy one linear pass is enough 0.0
11786 Fetching from uHunt 1.4n, Still Easy need to observe the pattern 0.0
bossbattle bossbattle 1.4n, Still Easy trick question 1391 1.8
lc0007 to replace with LeetCode link soon... 1.4n, Still Easy interpret x as string; reverse; convert to int again; check range 0 4.0
peasoup peasoup 1.4n, Still Easy one linear pass 771 2.4
thanos thanos 1.4n, Still Easy simple simulation; R is at least 2 2503 2.5
vote vote 1.4n, Still Easy follow the requirements 1584 2.2
12157 Fetching from uHunt 1.4o, Medium LA 4405 - KualaLumpur08; compute and compare the two plans 0.0
12643 Fetching from uHunt 1.4o, Medium it has tricky test cases 0.0
basicprogramming1 basicprogramming1 1.4o, Medium a nice summative problem for programming examination of a basic programming methodology course 201 4.0
battlesimulation battlesimulation 1.4o, Medium one pass; special check on 3! = 6 possible combinations of 3 combo moves 900 2.8
bitsequalizer bitsequalizer 1.4o, Medium analyzing patterns; also available at UVa 12545 - Bits Equalizer 174 4.5
lc3522 to replace with LeetCode link soon... 1.4o, Medium an easier version of Kattis - basicprogramming1 0 4.0
lc0058 to replace with LeetCode link soon... 1.5a, 1D Character Array split and report as asked; programming-skills; top-interview-150 0 2.0
11278 Fetching from uHunt 1.5b, Cipher, Easier map QWERTY keys to DVORAK 0.0
12896 Fetching from uHunt 1.5b, Cipher, Easier simple cipher; use mapper 0.0
13145 Fetching from uHunt 1.5b, Cipher, Easier shift alphabet values by +6 characters to read the problem statement; simple Caesar Cipher problem 0.0
conundrum conundrum 1.5b, Cipher, Easier simple cipher 5240 1.4
encodedmessage encodedmessage 1.5b, Cipher, Easier simple 2D grid cipher 2316 1.4
lc0006 to replace with LeetCode link soon... 1.5b, Cipher, Easier index manipulation exercise; top-interview-150 0 4.0
t9spelling t9spelling 1.5b, Cipher, Easier similar to (the reverse of) UVa 12896 2425 1.7
00245 Fetching from uHunt 1.5c, Cipher, Medium LA 5184 - WorldFinals Nashville95 0.0
11787 Fetching from uHunt 1.5c, Cipher, Medium follow the description 0.0
anewalphabet anewalphabet 1.5c, Cipher, Medium simple cipher; 26 characters 4154 1.8
lc0443 to replace with LeetCode link soon... 1.5c, Cipher, Medium Run-Length Encoding simulation; leetcode-75 0 4.0
piglatin piglatin 1.5c, Cipher, Medium simple; check the vowels that include 'y' and process it 916 2.1
secretmessage secretmessage 1.5c, Cipher, Medium just do as asked; use 2D grid 2866 1.7
tajna tajna 1.5c, Cipher, Medium simple 2D grid cipher 471 2.1
01200 Fetching from uHunt 1.5d, Input Parsing (Iter) LA 2972 - Tehran03; tokenize input 0.0
10906 Fetching from uHunt 1.5d, Input Parsing (Iter) BNF parsing; iterative solution 0.0
11878 Fetching from uHunt 1.5d, Input Parsing (Iter) expression parsing 0.0
autori autori 1.5d, Input Parsing (Iter) simple string tokenizer problem 11602 1.2
lc1678 to replace with LeetCode link soon... 1.5d, Input Parsing (Iter) simple iterative parser 0 2.0
pervasiveheartmonitor pervasiveheartmonitor 1.5d, Input Parsing (Iter) simple parsing; then finding average 950 1.7
timebomb timebomb 1.5d, Input Parsing (Iter) just a tedious input parsing problem; divisibility by 6 1174 1.8
00488 Fetching from uHunt 1.5e, Output Formatting, E use several loops 0.0
01605 Fetching from uHunt 1.5e, Output Formatting, E LA 4044 - NortheasternEurope07; we can answer this problem with just h=2 levels 0.0
12364 Fetching from uHunt 1.5e, Output Formatting, E 2D array check; check all possible digits [0..9] 0.0
display display 1.5e, Output Formatting, E unordered_map; map a digit -> enlarged 7x5 version 635 2.5
lc0151 to replace with LeetCode link soon... 1.5e, Output Formatting, E process the string as asked; leetcode-75; top-interview-150 0 4.0
musicalnotation musicalnotation 1.5e, Output Formatting, E simple but tedious 421 2.0
skener skener 1.5e, Output Formatting, E enlarging 2D character array 2067 1.5
lc1455 to replace with LeetCode link soon... 1.5f, Easy, Involving String tokenize and check 0 2.0
lc1880 to replace with LeetCode link soon... 1.5f, Easy, Involving String create function toInt(s); simple comparison 0 2.0
lc1945 to replace with LeetCode link soon... 1.5f, Easy, Involving String convert string to digits; then use sum-of-digits function 0 2.0
ptice ptice 1.5f, Easy, Involving String just a simple simulation 2100 1.5
sevenwonders sevenwonders 1.5f, Easy, Involving String one pass 4776 1.4
yinyangstones yinyangstones 1.5f, Easy, Involving String trick question; just check if number of whites equals to number of blacks 1365 1.8
10388 Fetching from uHunt 1.6a, Game (Card) card simulation; uses random number to determine moves; need data structure to maintain the face-up and face-down cards 0.0
12247 Fetching from uHunt 1.6a, Game (Card) This is a starred problem; refer to CP3/4 book 0.0
bela bela 1.6a, Game (Card) simple card scoring problem 3731 1.3
lc2347 to replace with LeetCode link soon... 1.6a, Game (Card) apply the poker hand rules as described 0 2.0
memorymatch memorymatch 1.6a, Game (Card) interesting simulation game; many corner cases 161 4.0
pokerhand pokerhand 1.6a, Game (Card) frequency count; report max 2173 1.4
shuffling shuffling 1.6a, Game (Card) simulate card shuffling operation 218 2.8
00255 Fetching from uHunt 1.6b, Game (Chess) check the validity of chess moves 0.0
00278 Fetching from uHunt 1.6b, Game (Chess) basic chess knowledge is needed; derive the closed form formulas 0.0
00696 Fetching from uHunt 1.6b, Game (Chess) ad hoc; chess 0.0
10284 Fetching from uHunt 1.6b, Game (Chess) FEN = Forsyth-Edwards Notation is a standard notation for describing board positions in a chess game 0.0
chess chess 1.6b, Game (Chess) bishop movements; either impossible, 0, 1, or 2 ways - one of this can be invalid; just use brute force 856 2.9
empleh empleh 1.6b, Game (Chess) the reverse problem of Kattis - helpme 245 1.8
helpme helpme 1.6b, Game (Chess) convert the given chess board into chess notation 302 2.4
lc0999 to replace with LeetCode link soon... 1.6b, Game (Chess) find the (r, c) of rook 'R'; simulate 4 directions of rook attacks 0 2.0
00947 Fetching from uHunt 1.6c, Game (Others), Easier similar to UVa 340 0.0
10189 Fetching from uHunt 1.6c, Game (Others), Easier simulate the classic Minesweeper game; similar to UVa 10279 0.0
11459 Fetching from uHunt 1.6c, Game (Others), Easier simulate it; similar to UVa 647 0.0
connectthedots connectthedots 1.6c, Game (Others), Easier classic children game; output formatting 213 3.6
gamerank gamerank 1.6c, Game (Others), Easier simulate the ranking update process 732 3.9
guessinggame guessinggame 1.6c, Game (Others), Easier use a 1D flag array; also available at UVa 10530 - Guessing Game 684 2.7
lc3248 to replace with LeetCode link soon... 1.6c, Game (Others), Easier simulating the movement of snake grid game 0 2.0
00584 Fetching from uHunt 1.6d, Game (Others), Harder simulation; games; reading comprehension 0.0
10813 Fetching from uHunt 1.6d, Game (Others), Harder follow the problem description 0.0
battleship battleship 1.6d, Game (Others), Harder simulation; reading comprehension; many corner cases 120 5.4
lc1275 to replace with LeetCode link soon... 1.6d, Game (Others), Harder simulate Tic-Tac-Toe game; programming-skills 0 2.0
rockpaperscissors rockpaperscissors 1.6d, Game (Others), Harder count wins and losses; output win average; also available at UVa 10903 - Rock-Paper-Scissors ... 820 3.7
tictactoe2 tictactoe2 1.6d, Game (Others), Harder check validity of Tic Tac Toe game; tricky; also available at UVa 10363 - Tic Tac Toe 167 5.3
turtlemaster turtlemaster 1.6d, Game (Others), Harder interesting board game to teach programming for children; simulation 323 2.9
00637 Fetching from uHunt 1.6e, Real Life, Easier application in printer driver software 0.0
13151 Fetching from uHunt 1.6e, Real Life, Easier marking programming exam; ad hoc; straightforward 0.0
chopin chopin 1.6e, Real Life, Easier you can learn a bit of music with this problem 823 1.8
compass compass 1.6e, Real Life, Easier your typical smartphone's compass function usually has this small feature 1529 2.0
fizzbuzz fizzbuzz 1.6e, Real Life, Easier actually just about easy divisibility properties 10274 1.3
lc0657 to replace with LeetCode link soon... 1.6e, Real Life, Easier simple robot movement simulation on a virtual 2D grid; programming-skills 0 2.0
trainpassengers trainpassengers 1.6e, Real Life, Easier create a verifier; be careful of corner cases 1807 2.1
wertyu wertyu 1.6e, Real Life, Easier use 2D mapper array to simplify the problem; also available at UVa 10082 - WERTYU 768 2.9
10528 Fetching from uHunt 1.6f, Real Life, Medium music knowledge in problem description 0.0
11736 Fetching from uHunt 1.6f, Real Life, Medium this is a (simplified) introduction to Computer Organization on how computer stores data in memory 0.0
beatspread beatspread 1.6f, Real Life, Medium be careful with boundary cases!; also available at UVa 10812 - Beat the Spread 980 2.4
lc1041 to replace with LeetCode link soon... 1.6f, Real Life, Medium virtual 2D grid traversal; simple observations; programming-skills 0 4.0
luhnchecksum luhnchecksum 1.6f, Real Life, Medium very similar (~95%) to UVa 11743 836 1.6
toilet toilet 1.6f, Real Life, Medium simulation; be careful of corner cases 1756 2.4
wordcloud wordcloud 1.6f, Real Life, Medium just a simulation; but be careful of corner cases 322 2.4
00706 Fetching from uHunt 1.6g, Real Life, Harder like in old digital display 0.0
01061 Fetching from uHunt 1.6g, Real Life, Harder LA 3736 - WorldFinals Tokyo07; try all eight possible blood + Rh types with the information given 0.0
01091 Fetching from uHunt 1.6g, Real Life, Harder LA 4786 - WorldFinals Harbin10; tedious simulation and reading comprehension 0.0
11279 Fetching from uHunt 1.6g, Real Life, Harder an extension of UVa 11278 problem; it is interesting to compare QWERTY and DVORAK keyboard layout 0.0
creditcard creditcard 1.6g, Real Life, Harder real life issue; precision error issue if we do not convert double (with just 2 digits after decimal point) into long lo... 123 6.3
tenis tenis 1.6g, Real Life, Harder Tennis scoring rules; tricky test cases; be careful 78 5.0
00579 Fetching from uHunt 1.6h, Time, Easier be careful with corner cases 0.0
12148 Fetching from uHunt 1.6h, Time, Easier easy with Gregorian Calendar; use method 'add' to add one day to previous date and see if it is the same as the current ... 0.0
friday friday 1.6h, Time, Easier the answer depends on the start day of the month 1059 1.9
justaminute justaminute 1.6h, Time, Easier linear pass; total seconds/(total minutes*60) 1512 1.7
lc1154 to replace with LeetCode link soon... 1.6h, Time, Easier use Python datetime library 0 2.0
marswindow marswindow 1.6h, Time, Easier simple advancing of year and month by 26 months or 2 years+2 months each; direct formula exists 830 2.0
savingdaylight savingdaylight 1.6h, Time, Easier convert hh:mm to minute; compute difference of ending and starting; then convert minute to hh:mm again 986 2.1
11947 Fetching from uHunt 1.6i, Time, Harder easier with Java GregorianCalendar 0.0
12822 Fetching from uHunt 1.6i, Time, Harder convert hh:mm:ss to second to simplify the problem; then this is just a tedious simulation problem 0.0
bestbefore bestbefore 1.6i, Time, Harder tedious; 3! = 6 possibilities to check 148 4.0
birthdayboy birthdayboy 1.6i, Time, Harder convert mm-dd into [0..364]; use DAT; find largest gap via brute force 108 4.6
natrij natrij 1.6i, Time, Harder convert hh:mm:ss to seconds; make sure the second time is larger than the first time; corner case: 24:00:00 1136 2.6
timezones timezones 1.6i, Time, Harder follow the description, tedious; also available at UVa 10371 - Time Zones 67 5.3
00185 Fetching from uHunt 1.6j, Roman Numerals also involving backtracking 0.0
00344 Fetching from uHunt 1.6j, Roman Numerals count Roman chars used in [1..N] 0.0
00759 Fetching from uHunt 1.6j, Roman Numerals validation problem 0.0
12397 Fetching from uHunt 1.6j, Roman Numerals each Roman digit has a value 0.0
lc0013 to replace with LeetCode link soon... 1.6j, Roman Numerals classic Roman to Integer conversion; programming-skills; top-interview-150 0 2.0
rimski rimski 1.6j, Roman Numerals to Roman/to Decimal conversion problem; use next permutation to be sure 118 4.5
romanholidays romanholidays 1.6j, Roman Numerals generate and sort the first 1K Roman strings; ''M'' is at index 945; append prefix 'M' for numbers larger than 1K 92 3.6
11638 Fetching from uHunt 1.6k, Time Waster, Easier simulation; needs to use bitmask for parameter C 0.0
12085 Fetching from uHunt 1.6k, Time Waster, Easier LA 2189 - Dhaka06; watch out for PE 0.0
12608 Fetching from uHunt 1.6k, Time Waster, Easier simulation with several corner cases 0.0
asciiaddition asciiaddition 1.6k, Time Waster, Easier a+b problem in text format 509 1.9
glitchbot glitchbot 1.6k, Time Waster, Easier O(n^2) simulation; only output one answer 1036 2.0
pachydermpeanutpacking pachydermpeanutpacking 1.6k, Time Waster, Easier time waster; simple one loop simulation 322 1.9
printingcosts printingcosts 1.6k, Time Waster, Easier clear time waster; the hard part is in parsing the costs of each character in the problem description 705 2.2
00405 Fetching from uHunt 1.6l, Time Waster, Harder simulation 0.0
10188 Fetching from uHunt 1.6l, Time Waster, Harder simulation 0.0
11717 Fetching from uHunt 1.6l, Time Waster, Harder tricky simulation 0.0
12280 Fetching from uHunt 1.6l, Time Waster, Harder a tedious problem 0.0
froggie froggie 1.6l, Time Waster, Harder just a simulation; but many corner cases; S can be 0 296 6.8
functionalfun functionalfun 1.6l, Time Waster, Harder just follow the description; 5 cases; tedious parsing problem; requires a kind of mapper 487 1.9
windows windows 1.6l, Time Waster, Harder LA 7162 - WorldFinals Marrakech15; tedious simulation problem; also available at UVa 01721 - Window Manager 92 7.6
12150 Fetching from uHunt 2.2a, 1D Array, Medium simple manipulation 0.0
12356 Fetching from uHunt 2.2a, 1D Array, Medium similar to deletion in doubly linked lists but we can still use a 1D array for the underlying data structure 0.0
downtime downtime 2.2a, 1D Array, Medium 1D array; use Fenwick Tree-like operation for Range Update Point Query 1068 3.2
fluortanten fluortanten 2.2a, 1D Array, Medium remove Bjorn first; then do O(n) pass to check where is Bjorn's optimal position 181 3.1
greedilyincreasing greedilyincreasing 2.2a, 1D Array, Medium just 1D array manipulation; this is not the DP-LIS problem 1151 1.9
jollyjumpers jollyjumpers 2.2a, 1D Array, Medium 1D Boolean flags to check [1..n-1]; also available at UVa 10038 - Jolly Jumpers 413 3.4
lc0088 to replace with LeetCode link soon... 2.2a, 1D Array, Medium do merge of Merge sort; top-interview-150 0 2.0
lc0605 to replace with LeetCode link soon... 2.2a, 1D Array, Medium tricky 1D array processing; leetcode-75 0 2.0
10978 Fetching from uHunt 2.2c, 1D Array, Harder 1D string array 0.0
12662 Fetching from uHunt 2.2c, 1D Array, Harder 1D array manipulation; brute force 0.0
13048 Fetching from uHunt 2.2c, 1D Array, Harder use 1D Boolean array; simulate 0.0
divideby100 divideby100 2.2c, 1D Array, Harder big 1D character array processing; be careful 557 4.2
lc0238 to replace with LeetCode link soon... 2.2c, 1D Array, Harder use prefix and suffix products; leetcode-75; top-100-liked; top-interview-150 0 4.0
lc1869 to replace with LeetCode link soon... 2.2c, 1D Array, Harder split s using 0 as delimiter; take token with the max length; do the same but using 1 as delimiter; compare 0 2.0
mastermind mastermind 2.2c, 1D Array, Harder 1D array manipulation to count r and s 446 2.4
pivot pivot 2.2c, 1D Array, Harder static range min/max query problem; special condition allows this problem to be solvable in O(n) using help of 1D arrays 1723 3.2
11581 Fetching from uHunt 2.2d, 2D Array, Medium simulate the process 0.0
12667 Fetching from uHunt 2.2d, 2D Array, Medium use both 1D and 2D arrays to store submission status 0.0
epigdanceoff epigdanceoff 2.2d, 2D Array, Medium count number of CCs on 2D grid; simpler solution exists: count the number of blank columns plus one 505 1.9
flowshop flowshop 2.2d, 2D Array, Medium interesting 2D array manipulation 392 2.5
imageprocessing imageprocessing 2.2d, 2D Array, Medium interesting 2D array manipulation 344 2.1
lc0027 to replace with LeetCode link soon... 2.2d, 2D Array, Medium use Partition algorithm (two pointers) for in-place solution; top-interview-150 0 2.0
lc1351 to replace with LeetCode link soon... 2.2d, 2D Array, Medium go row by row; right to left, O(m+n) 0 2.0
nineknights nineknights 2.2d, 2D Array, Medium 2D array checks; 8 directions 881 1.9
00466 Fetching from uHunt 2.2e, 2D Array, Harder core functions: rotate and reflect 0.0
12291 Fetching from uHunt 2.2e, 2D Array, Harder do as asked; a bit tedious 0.0
2048 2048 2.2e, 2D Array, Harder just a 2D array manipulation problem; utilize symmetry using 90 degrees rotation(s) to reduce 4 cases into 1 3150 2.1
flagquiz flagquiz 2.2e, 2D Array, Harder array of array of strings; be careful; duplicates may exists 167 3.7
funhouse funhouse 2.2e, 2D Array, Harder 2D array manipulation; note the direction update 700 2.0
lc0054 to replace with LeetCode link soon... 2.2e, 2D Array, Harder heavy 2D matrix indexing; use dr/dc technique; programming-skills; top-100-liked; top-interview-150 0 4.0
rings2 rings2 2.2e, 2D Array, Harder more challenging 2D array manipulation; special output formatting style 385 3.8
10107 Fetching from uHunt 2.2f, Sorting, Easier find median of a growing/dynamic list of integers; we can use multiple calls of nth_element in algorithm 0.0
12709 Fetching from uHunt 2.2f, Sorting, Easier LA 6650 - Dhaka13; although the problem has a complicated story; it has a very easy solution with sort routine 0.0
basicprogramming2 basicprogramming2 2.2f, Sorting, Easier a nice problem about basic sorting applications 189 3.4
height height 2.2f, Sorting, Easier insertion sort simulation 899 2.0
lc0217 to replace with LeetCode link soon... 2.2f, Sorting, Easier sort; check adjacent integers 0 2.0
lc1657 to replace with LeetCode link soon... 2.2f, Sorting, Easier check if set of chars and its sorted frequency signatures are the same; leetcode-75 0 4.0
mjehuric mjehuric 2.2f, Sorting, Easier a direct simulation of a bubble sort algorithm 1349 1.6
sidewayssorting sidewayssorting 2.2f, Sorting, Easier stable_sort or sort multi-fields of columns of a 2D array; ignore case 857 2.0
lc0219 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sort (keep the original indices as pair (v, i)); check successive elements; top-interview-150 0 2.0
lc1502 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sort; check gap of successive elements; programming-skills 0 2.0
lc1637 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sort; remove duplicate x-s; check successive elements 0 2.0
lc1984 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sort; check elements that are k indices apart 0 2.0
lc2342 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sum-of-digits function; sort by (sod(n), n); check successive elements 0 4.0
lc2465 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sort; two pointers: smallest and largest 0 2.0
lc2500 to replace with LeetCode link soon... 2.2g, Sorting, Simple Greedy sort each row; process per column 0 2.0
01610 Fetching from uHunt 2.2h, Sorting, Harder LA 6196 - MidAtlanticUSA12; median 0.0
11321 Fetching from uHunt 2.2h, Sorting, Harder be careful with negative mod! 0.0
classy classy 2.2h, Sorting, Harder sort using modified comparison function; a bit of string parsing/tokenization 1633 4.5
dyslectionary dyslectionary 2.2h, Sorting, Harder sort the reverse of original string; output formatting 775 3.4
lc0001 to replace with LeetCode link soon... 2.2h, Sorting, Harder classic; O(n log n) solution: sort + two pointers; top-100-liked; top-interview-150 0 2.0
musicyourway musicyourway 2.2h, Sorting, Harder stable_sort; custom comparison function 404 2.4
sortofsorting sortofsorting 2.2h, Sorting, Harder stable_sort or sort multi-fields 2667 2.2
11462 Fetching from uHunt 2.2i, Special Sorting standard Counting Sort problem 0.0
11495 Fetching from uHunt 2.2i, Special Sorting requires O(n log n) merge sort 0.0
13212 Fetching from uHunt 2.2i, Special Sorting requires O(n log n) merge sort 0.0
bread bread 2.2i, Special Sorting inversion count; hard to derive 249 5.0
lc1122 to replace with LeetCode link soon... 2.2i, Special Sorting counting sort variant using arr2 order 0 2.0
mali mali 2.2i, Special Sorting Counting Sort two arrays; greedy matching largest+smallest at that point 97 5.1
12571 Fetching from uHunt 2.2j, Bit Manipulation precalculate AND operations 0.0
12720 Fetching from uHunt 2.2j, Bit Manipulation observe the pattern in this binary to decimal conversion variant; involves modulo arithmetic 0.0
bitbybit bitbybit 2.2j, Bit Manipulation be very careful with and + or corner cases 955 2.9
deathstar deathstar 2.2j, Bit Manipulation can be solved with bit manipulation 415 2.0
lc0338 to replace with LeetCode link soon... 2.2j, Bit Manipulation bit_count; trivial; leetcode-75 0 2.0
lc1318 to replace with LeetCode link soon... 2.2j, Bit Manipulation check all 31 bits; a few sub-cases per bit; leetcode-75 0 4.0
snapperhard snapperhard 2.2j, Bit Manipulation bit manipulation; find the pattern; the easier version is also available at Kattis - snappereasy 501 2.3
10523 Fetching from uHunt 2.2k, Big Integer, Easier BigInteger addition; multiplication; and power 0.0
10925 Fetching from uHunt 2.2k, Big Integer, Easier BigInteger addition and division 0.0
11879 Fetching from uHunt 2.2k, Big Integer, Easier BigInteger: mod; divide; subtract; equals 0.0
lc0043 to replace with LeetCode link soon... 2.2k, Big Integer, Easier basic Big Integer multiplication; programming-skills 0 4.0
primaryarithmetic primaryarithmetic 2.2k, Big Integer, Easier not a Big Integer problem but a simulation of basic addition 399 2.7
simpleaddition simpleaddition 2.2k, Big Integer, Easier that A+B on BigInteger question 1913 1.9
wizardofodds wizardofodds 2.2k, Big Integer, Easier if K is bigger than 350, the answer is clear; else just check if 2^K ≥ N 488 2.6
lc2259 to replace with LeetCode link soon... 2.2l, Big Integer, Harder we can use Big Integer technique to solve this 0 2.0
01062 Fetching from uHunt 2.2m, Stack LA 3752 - WorldFinals Tokyo07; simulation with stack; maximum answer is 26 stacks; O(n) solution exists 0.0
13055 Fetching from uHunt 2.2m, Stack nice problem about stack 0.0
evenup evenup 2.2m, Stack use stack to solve this problem 1273 2.7
lc0394 to replace with LeetCode link soon... 2.2m, Stack more complex stack simulation; leetcode-75; top-100-liked 0 4.0
pairingsocks pairingsocks 2.2m, Stack simulation using two stacks; just do as asked 556 3.0
restaurant restaurant 2.2m, Stack simulation with stack-based concept; drop plates at stack 2 (LIFO); use move 2-$gt;1 to reverse order; take from stack 1... 364 4.5
throwns throwns 2.2m, Stack use stack of egg positions to help with the undo operation; be careful of corner cases involving modulo operation 1091 2.6
00551 Fetching from uHunt 2.2n, Stack-based Problems bracket matching; use stack 0.0
00727 Fetching from uHunt 2.2n, Stack-based Problems Infix to Postfix conversion problem 0.0
11111 Fetching from uHunt 2.2n, Stack-based Problems bracket matching with twists 0.0
bungeebuilder bungeebuilder 2.2n, Stack-based Problems clever usage of stack; linear pass; bracket (mountain) matching variant 83 3.3
circuitmath circuitmath 2.2n, Stack-based Problems postfix calculator problem 918 2.4
delimitersoup delimitersoup 2.2n, Stack-based Problems bracket matching; stack 382 1.9
lc0901 to replace with LeetCode link soon... 2.2n, Stack-based Problems process left-to-right (each day); monotonic non-increasing stack (price, days_increasing); leetcode-75 0 4.0
11988 Fetching from uHunt 2.2o, List/Queue/Deque rare linked list problem 0.0
12108 Fetching from uHunt 2.2o, List/Queue/Deque simulation with N queues 0.0
integerlists integerlists 2.2o, List/Queue/Deque use deque for fast deletion from front (normal) & back (reversed list); use stack to reverse the final list if it is... 882 4.8
joinstrings joinstrings 2.2o, List/Queue/Deque all '+' operations must be O(1) 959 4.1
lc0232 to replace with LeetCode link soon... 2.2o, List/Queue/Deque the interesting implementation of queue with two stacks: in-stack and out-stack 0 2.0
sim sim 2.2o, List/Queue/Deque use list and its iterator 99 2.0
teque teque 2.2o, List/Queue/Deque all operations must be O(1) 766 3.3
lc0011 to replace with LeetCode link soon... 2.2p, 1D Array, Two Pointers two pointers, l=0, r=n-1; we can always move the shorter pointer inside; leetcode-75; top-100-liked; top-interview-150 0 4.0
lc0167 to replace with LeetCode link soon... 2.2p, 1D Array, Two Pointers two pointers: leftmost and rightmost; top-interview-150 0 4.0
lc0283 to replace with LeetCode link soon... 2.2p, 1D Array, Two Pointers two pointers: leftmost zero and cur; programming-skills; leetcode-75; top-100-liked 0 2.0
lc0392 to replace with LeetCode link soon... 2.2p, 1D Array, Two Pointers variant of merge of Merge sort; leetcode-75; top-interview-150 0 2.0
lc1768 to replace with LeetCode link soon... 2.2p, 1D Array, Two Pointers variant of merge of Merge sort; programming-skills; leetcode-75 0 2.0
00261 Fetching from uHunt 2.2q, Sliding Window sliding window variant 0.0
01121 Fetching from uHunt 2.2q, Sliding Window LA 2678 - SouthEasternEurope06; sliding window variant 0.0
11536 Fetching from uHunt 2.2q, Sliding Window sliding window variant 0.0
lc0003 to replace with LeetCode link soon... 2.2q, Sliding Window increase char freq when extending; reduce window size if duplicate is seen; top-100-liked; top-interview-150 0 4.0
lc0643 to replace with LeetCode link soon... 2.2q, Sliding Window slide the window of size k; keep the max; divide by k; leetcode-75 0 2.0
sound sound 2.2q, Sliding Window sliding window variant 4; max and min; similar to Kattis - treeshopping 104 5.3
subseqhard subseqhard 2.2q, Sliding Window interesting sliding window variant 1119 3.9
lc0002 to replace with LeetCode link soon... 2.2r, Linked List Exercises simple problem but in reverse SLL mode; programming-skills; top-100-liked; top-interview-150 0 4.0
lc0021 to replace with LeetCode link soon... 2.2r, Linked List Exercises merge of merge sort in linked list way; programming-skills; top-100-liked; top-interview-150 0 2.0
lc0206 to replace with LeetCode link soon... 2.2r, Linked List Exercises classic SLL reversal task; programming-skills; leetcode-75; top-100-liked 0 2.0
lc0445 to replace with LeetCode link soon... 2.2r, Linked List Exercises like LC0002; but need to use two stacks; programming-skills 0 4.0
lc2095 to replace with LeetCode link soon... 2.2r, Linked List Exercises first pass to count n; second pass to go to the middle vertex and to skip it; leetcode-75 0 4.0
lc2130 to replace with LeetCode link soon... 2.2r, Linked List Exercises use recursion; as it unwinds, sum the values of leftmost and rightmost pointers; leetcode-75 0 4.0
01203 Fetching from uHunt 2.3a, Priority Queue LA 3135 - Beijing04; use priority_queue 0.0
11997 Fetching from uHunt 2.3a, Priority Queue sort the lists; merge two sorted lists using priority_queue to keep the K-th smallest sum every time 0.0
jugglingpatterns jugglingpatterns 2.3a, Priority Queue PQ simulation; reading comprehension 48 6.3
knigsoftheforest knigsoftheforest 2.3a, Priority Queue PQ simulation after sorting the entries by year 184 3.6
lc2462 to replace with LeetCode link soon... 2.3a, Priority Queue min PQ simulation; two pointers: i=0 and j=n-1; move inwards; leetcode-75 0 4.0
numbertree numbertree 2.3a, Priority Queue not a direct priority queue problem, but the indexing strategy is similar to binary heap indexing 1760 2.1
stockprices stockprices 2.3a, Priority Queue PQ simulation; both max and min PQ 109 3.7
00499 Fetching from uHunt 2.3b, DAT, ASCII ASCII keys 0.0
11340 Fetching from uHunt 2.3b, DAT, ASCII ASCII keys 0.0
11577 Fetching from uHunt 2.3b, DAT, ASCII A-Z keys 0.0
alphabetspam alphabetspam 2.3b, DAT, ASCII count the frequencies of lowercase, uppercase, and whitespace characters 3902 1.4
lc0389 to replace with LeetCode link soon... 2.3b, DAT, ASCII DAT ('a'..'z'); programming-skills 0 2.0
quickbrownfox quickbrownfox 2.3b, DAT, ASCII pangram; frequency counting of 26 alphabets 4433 1.6
soundex soundex 2.3b, DAT, ASCII DAT for soundex A-Z code mapping; also available at UVa 10260 - Soundex 106 2.9
01368 Fetching from uHunt 2.3c, DAT, Others for each column j, find the highest frequency character among all j-th column of all m DNA strings 0.0
11203 Fetching from uHunt 2.3c, DAT, Others count frequency of x/y/z 0.0
bookingaroom bookingaroom 2.3c, DAT, Others only 100 rooms; use 1D Boolean array 2849 1.7
busnumbers busnumbers 2.3c, DAT, Others only 1000 bus numbers; use 1D Boolean array 2776 2.4
freefood freefood 2.3c, DAT, Others only 365 days in a year 1965 1.5
lc0645 to replace with LeetCode link soon... 2.3c, DAT, Others DAT [1..10000]; find key with freq 2 (repeated) and 0 (missing) 0 2.0
princesspeach princesspeach 2.3c, DAT, Others DAT; linear pass 839 2.1
12049 Fetching from uHunt 2.3d, Hash Table (set), E unordered_multiset manipulation 0.0
13148 Fetching from uHunt 2.3d, Hash Table (set), E we can store all precomputed answers - which are given - into unordered_set 0.0
cd cd 2.3d, Hash Table (set), E unordered_set is faster than set here; or use modified merge as the input is sorted; also available at UVa 11849 - CD 3176 5.3
esej esej 2.3d, Hash Table (set), E use unordered_set to prevent duplicate 509 3.3
lc2215 to replace with LeetCode link soon... 2.3d, Hash Table (set), E use set for fast tests; leetcode-75 0 2.0
shiritori shiritori 2.3d, Hash Table (set), E linear pass; use unordered_set to keep track of words that have been called 295 2.9
greetingcard greetingcard 2.3e, Hash Table (set), H use unordered_set; only 12 neighbors 607 4.9
11348 Fetching from uHunt 2.3f, Hash Table (map), E use map and set to check uniqueness 0.0
11629 Fetching from uHunt 2.3f, Hash Table (map), E use map 0.0
competitivearcadebasketball competitivearcadebasketball 2.3f, Hash Table (map), E use unordered_map 209 2.8
conformity conformity 2.3f, Hash Table (map), E use unordered_map to count frequencies of the sorted permutations of 5 ids; also available at UVa 11286 - Conformity 1100 1.9
grandpabernie grandpabernie 2.3f, Hash Table (map), E use unordered_map plus (sorted) vector 1065 3.2
lc1679 to replace with LeetCode link soon... 2.3f, Hash Table (map), E frequency Counter; pairings; leetcode-75 0 4.0
recount recount 2.3f, Hash Table (map), E use map; frequency counting 1163 2.0
lc0347 to replace with LeetCode link soon... 2.3g, Hash Table (Counter) use Counter to count frequency; sort by frequencies; top k; top-100-liked 0 4.0
10145 Fetching from uHunt 2.3h, Hash Table (map), H use map and set 0.0
11860 Fetching from uHunt 2.3h, Hash Table (map), H use set and map; linear scan 0.0
addingwords addingwords 2.3h, Hash Table (map), H use unordered_map 1880 3.9
awkwardparty awkwardparty 2.3h, Hash Table (map), H use unordered_map to running max and running min; report the largest difference 611 3.0
basicinterpreter basicinterpreter 2.3h, Hash Table (map), H the harder version of Kattis - variablearithmetic; tedious; be careful; print string inside double quotes verbatim 152 6.7
10815 Fetching from uHunt 2.3i, Balanced BST (set) use set and string 0.0
11136 Fetching from uHunt 2.3i, Balanced BST (set) use multiset 0.0
13037 Fetching from uHunt 2.3i, Balanced BST (set) we can use set or a sorted array 0.0
bst bst 2.3i, Balanced BST (set) simulate special BST [1..N] insertions using set 449 7.3
candydivision candydivision 2.3i, Balanced BST (set) complete search from 1 to sqrt(N); insert all divisors into set for automatic sorting and elimination of duplicates 702 3.4
compoundwords compoundwords 2.3i, Balanced BST (set) use set extensively; iterator 1807 1.7
lc0056 to replace with LeetCode link soon... 2.3i, Balanced BST (set) maintain set of intervals using bBST (set); do quick merging of intervals; top-100-liked; top-interview-150 0 4.0
10138 Fetching from uHunt 2.3j, Balanced BST (map) map plates to bills; entrance time; and position 0.0
11308 Fetching from uHunt 2.3j, Balanced BST (map) use map and set 0.0
12504 Fetching from uHunt 2.3j, Balanced BST (map) use map; string to string 0.0
administrativeproblems administrativeproblems 2.3j, Balanced BST (map) use several maps as the output (of spy names) has to be sorted; be careful of corner cases 194 6.3
doctorkattis doctorkattis 2.3j, Balanced BST (map) Max Priority Queue with frequent (increaseKey) updates; use map 114 4.7
kattissquest kattissquest 2.3j, Balanced BST (map) use map of priority queues; other solutions exist 834 3.1
srednji srednji 2.3j, Balanced BST (map) go left and right of B; use fast data structure like map to help determine the result fast 164 4.1
10909 Fetching from uHunt 2.3k, Order Statistics Tree involves dynamic selection; use pb\_ds, Fenwick Tree, or augment balanced BST 0.0
babynames babynames 2.3k, Order Statistics Tree dynamic rank problem; use two pb_ds 87 5.5
continuousmedian continuousmedian 2.3k, Order Statistics Tree dynamic selection problem; specifically the median values; pb_ds helps 140 3.9
cookieselection cookieselection 2.3k, Order Statistics Tree map large integers to up to 600K integers; use pb_ds or Fenwick Tree and the select(median) operation of Fenwick Tree 923 4.3
gcpc gcpc 2.3k, Order Statistics Tree dynamic rank problem; pb_ds helps 876 5.3
lc0100 to replace with LeetCode link soon... 2.3l, BT Exercises, E recursive check; top-interview-150 0 2.0
lc0104 to replace with LeetCode link soon... 2.3l, BT Exercises, E recursive height check; leetcode-75; top-100-liked; top-interview-150 0 2.0
lc0236 to replace with LeetCode link soon... 2.3l, BT Exercises, E find the first vertex using postorder where both p and q are seen; leetcode-75; top-100-liked; top-interview-150 0 4.0
lc0437 to replace with LeetCode link soon... 2.3l, BT Exercises, E for each vertex, run preorder traversal; check if the path sum equals to target; leetcode-75; top-100-liked 0 4.0
lc0872 to replace with LeetCode link soon... 2.3l, BT Exercises, E run inorder traversals on both trees; picking only the leaves; compare them; leetcode-75 0 2.0
lc1372 to replace with LeetCode link soon... 2.3l, BT Exercises, E modified preorder traversal; reset counter if same direction; add counter if zig-zag-ing; leetcode-75 0 4.0
lc1448 to replace with LeetCode link soon... 2.3l, BT Exercises, E modified preorder traversal; keep the largest along the way; leetcode-75 0 4.0
lc0098 to replace with LeetCode link soon... 2.3m, BST Exercises recursive BST property validator; top-100-liked; top-interview-150 0 4.0
lc0230 to replace with LeetCode link soon... 2.3m, BST Exercises inorder traversal; report the k-th element; top-100-liked; top-interview-150 0 4.0
lc0450 to replace with LeetCode link soon... 2.3m, BST Exercises code BST deletion sub-cases; leetcode-75 0 4.0
lc0530 to replace with LeetCode link soon... 2.3m, BST Exercises the min gap is between successive elements during inorder traversal; same as LC 0783; top-interview-150 0 2.0
lc0700 to replace with LeetCode link soon... 2.3m, BST Exercises the classic BST search process; leetcode-75 0 2.0
lc0897 to replace with LeetCode link soon... 2.3m, BST Exercises create new skewed BST using inorder traversal of original BST 0 2.0
lc0938 to replace with LeetCode link soon... 2.3m, BST Exercises customize inorder traversal of BST 0 2.0
00599 Fetching from uHunt 2.4a, Graph Data Structures V-E = number of CCs; use a bitset of size 26 to count the number of vertices that have some edge 0.0
11550 Fetching from uHunt 2.4a, Graph Data Structures graph representation; incidence matrix 0.0
11991 Fetching from uHunt 2.4a, Graph Data Structures Adjacency List 0.0
abinitio abinitio 2.4a, Graph Data Structures combo: EL input, AM as working graph DS, AL output (in hash format); all operations must be O(V) or better 104 7.3
chopwood chopwood 2.4a, Graph Data Structures Prüfer sequence; use priority_queue 258 3.5
traveltheskies traveltheskies 2.4a, Graph Data Structures (graph) DS manipulation; an array of ALs (one per each day); simulate the number of people day by day 188 3.2
01197 Fetching from uHunt 2.4b, Union-Find LA 2817 - Kaohsiung03; Connected Components 0.0
01329 Fetching from uHunt 2.4b, Union-Find LA 3027 - SouthEasternEurope04; interesting UFDS variant; modify the union and find routine 0.0
10608 Fetching from uHunt 2.4b, Union-Find find the set with the largest element 0.0
10685 Fetching from uHunt 2.4b, Union-Find find the set with the largest element 0.0
almostunionfind almostunionfind 2.4b, Union-Find new operation: move; idea: do not destroy the parent array structure; also available at UVa 11987 - Almost Union-Find 618 7.0
control control 2.4b, Union-Find LA 7480 - Singapore15; simulation of UFDS; size of set; number of disjoint sets 424 4.6
ladice ladice 2.4b, Union-Find size of set; decrement one per usage 615 2.8
unionfind unionfind 2.4b, Union-Find basic UFDS; similar to UVa 00793 1086 4.8
11402 Fetching from uHunt 2.4c, Tree-related DS Segment Tree with lazy updates 0.0
11423 Fetching from uHunt 2.4c, Tree-related DS clever usage of Fenwick Tree and large array; important hint: look at the constraints carefully 0.0
12299 Fetching from uHunt 2.4c, Tree-related DS Segment Tree with a few point (not range) updates; RMQs 0.0
fenwick fenwick 2.4c, Tree-related DS basic Fenwick Tree; use long long 695 4.5
justforsidekicks justforsidekicks 2.4c, Tree-related DS use six Fenwick Trees, one for each gem type 359 3.8
moviecollection moviecollection 2.4c, Tree-related DS LA 5902 - NorthWesternEurope11; not a stack but a dynamic RSQ problem; also available at UVa 01513 - Movie collection 547 5.5
supercomputer supercomputer 2.4c, Tree-related DS easy problem if we use Fenwick Tree 760 3.8
00750 Fetching from uHunt 3.2a, Pre-calculate-able classic backtracking problem; only 92 possible 8-queens positions 0.0
10128 Fetching from uHunt 3.2a, Pre-calculate-able backtracking with pruning; try all $N!$ permutations that satisfy the requirement; 13! will TLE; pre-calculate the resul... 0.0
10276 Fetching from uHunt 3.2a, Pre-calculate-able insert a number one by one 0.0
cardtrick2 cardtrick2 3.2a, Pre-calculate-able n <= 13, we can simulate the process using queue and precalculate all 13 possible answers 869 1.6
foolingaround foolingaround 3.2a, Pre-calculate-able there are only 379 different values of N where Bob wins; pre-calculateable 117 5.8
lc0052 to replace with LeetCode link soon... 3.2a, Pre-calculate-able pre-calculate answers for n = 1 to 9; top-interview-150 0 6.0
sgcoin sgcoin 3.2a, Pre-calculate-able we can either brute force short string message; precompute all possible hash values; or come up with O(1) solution 271 2.4
12488 Fetching from uHunt 3.2b, Iterative (Two Loops), E 2 nested loops; simulate overtaking process 0.0
blackfriday blackfriday 3.2b, Iterative (Two Loops), E 2D nested loops; frequency counting 2384 2.2
closestsums closestsums 3.2b, Iterative (Two Loops), E sort and then do O(n^2) pairings; also available at UVa 10487 - Closest Sums 1105 2.9
golombrulers golombrulers 3.2b, Iterative (Two Loops), E 2D nested loops; additional 1D loops for checking 297 3.2
lc3184 to replace with LeetCode link soon... 3.2b, Iterative (Two Loops), E 2 nested loops 0 2.0
01588 Fetching from uHunt 3.2c, Iterative (Two Loops), H LA 3712 - NorthEasternEurope06; good iterative brute force problem; beware of corner cases 0.0
00441 Fetching from uHunt 3.2d, Three+ Nested Loops, E 6 nested loops; easy 0.0
12515 Fetching from uHunt 3.2d, Three+ Nested Loops, E 3 nested loops 0.0
12844 Fetching from uHunt 3.2d, Three+ Nested Loops, E 5 nested loops; scaled down version of UVa 10202; do observations first 0.0
cudoviste cudoviste 3.2d, Three+ Nested Loops, E 4 nested loops; the inner loops is just 2x2; 5 possibilities of crushed cars; skip 2x2 area that contains building 1194 1.4
lc1790 to replace with LeetCode link soon... 3.2d, Three+ Nested Loops, E 3 nested loops 0 2.0
npuzzle npuzzle 3.2d, Three+ Nested Loops, E 4 nested loops; easy 683 2.2
set set 3.2d, Three+ Nested Loops, E 4 nested loops; easy 364 1.8
00386 Fetching from uHunt 3.2e, Three+ Nested Loops, H 4 nested loops with pruning 0.0
10660 Fetching from uHunt 3.2e, Three+ Nested Loops, H 7 nested loops; Manhattan distance 0.0
11804 Fetching from uHunt 3.2e, Three+ Nested Loops, H 5 nested loops 0.0
calculatingdartscores calculatingdartscores 3.2e, Three+ Nested Loops, H 6 nested loops but easy; see if a*i +b*j + c*k == n 752 2.8
lc2352 to replace with LeetCode link soon... 3.2e, Three+ Nested Loops, H 3 nested loops solution is still acceptable; leetcode-75 0 4.0
lektira lektira 3.2e, Three+ Nested Loops, H 2 nested loops to try all 2 cutting points plus 1 more loop to actually do the reversing of sub words 376 3.2
tautology tautology 3.2e, Three+ Nested Loops, H try all 2^5 = 32 values with pruning; also available at UVa 11108 - Tautology 160 3.4
00234 Fetching from uHunt 3.2f, Iterative (Permutation) LA 5173 - WorldFinals Phoenix94; use next_permutation; simulation 0.0
01064 Fetching from uHunt 3.2f, Iterative (Permutation) LA 3808 - WorldFinals Tokyo07; permutation of up to 5 messages; simulation; mind the word 'consecutive' 0.0
11742 Fetching from uHunt 3.2f, Iterative (Permutation) try all permutations 0.0
dancerecital dancerecital 3.2f, Iterative (Permutation) try all R! permutations; compare adjacent routines 274 4.2
dreamer dreamer 3.2f, Iterative (Permutation) try all 8! permutations of digits; check if the date is valid; output earliest valid date 406 2.0
lc0046 to replace with LeetCode link soon... 3.2f, Iterative (Permutation) C++ next_permutation from sorted to reverse-sorted permutations; top-100-liked; top-interview-150 0 4.0
veci veci 3.2f, Iterative (Permutation) try all permutations; get the one that is larger than X 1193 1.8
00639 Fetching from uHunt 3.2g, Iterative (Combination) generate 2^(4x4) = 2^16 combinations and prune 0.0
01047 Fetching from uHunt 3.2g, Iterative (Combination) LA 3278 - WorldFinals Shanghai05; try all 2^n subsets of towers to be taken; use inclusion-exclusion principle 0.0
12694 Fetching from uHunt 3.2g, Iterative (Combination) LA 6606 - Phuket13; it is safest to just brute force all 2^20 possibilities; greedy solution should be possible too 0.0
geppetto geppetto 3.2g, Iterative (Combination) try all 2^N subsets of ingredients 305 3.3
lc0077 to replace with LeetCode link soon... 3.2g, Iterative (Combination) standard nCk; use itertools.combinations; top-interview-150 0 4.0
squaredeal squaredeal 3.2g, Iterative (Combination) try all 3! permutations of rectangles and try all 2^3 combinations of rectangle orientations; test figure 1.a and 1.b co... 232 4.6
zagrade zagrade 3.2g, Iterative (Combination) try all subsets of bracket pairs to be removed 298 3.1
00725 Fetching from uHunt 3.2h, Try All Answers try all possible answers 0.0
10908 Fetching from uHunt 3.2h, Try All Answers 4 nested loops; try all possible odd square lengths 0.0
communication communication 3.2h, Try All Answers try all possible bytes; apply the bitmask formula 764 2.0
flexible flexible 3.2h, Try All Answers try all possible answers 2354 1.7
islands islands 3.2h, Try All Answers try all possible subsets; prune the non-contiguous ones (only 55 valid bitmasks between [0..1023]); check the 'island' p... 443 2.6
lc2843 to replace with LeetCode link soon... 3.2h, Try All Answers create helper function is_symmetric; try all numbers between low..high 0 2.0
walls walls 3.2h, Try All Answers try whether the answer is 1/2/3/4; or Impossible; use up to 4 nested loops 513 4.0
01225 Fetching from uHunt 3.2i, Math Simulation, E LA 3996 - Danang07; N is small 0.0
10346 Fetching from uHunt 3.2i, Math Simulation, E interesting simulation problem 0.0
easiest easiest 3.2i, Math Simulation, E complete search; sum of digit 3991 1.6
growlinggears growlinggears 3.2i, Math Simulation, E physics of parabola; derivation; try all gears 496 2.4
lc1823 to replace with LeetCode link soon... 3.2i, Math Simulation, E use Josephus formula 0 4.0
lc2427 to replace with LeetCode link soon... 3.2i, Math Simulation, E try all x; a and b are small 0 2.0
trollhunt trollhunt 3.2i, Math Simulation, E brute force; simple 976 2.6
videospeedup videospeedup 3.2i, Math Simulation, E brute force; simple for loop; do as asked 298 2.0
lc0970 to replace with LeetCode link soon... 3.2j, Math Simulation, M the values of x^i or y^j will grow fast; search space is small 0 4.0
00616 Fetching from uHunt 3.2k, Math Simulation, H brute force up to sqrt(n); get pattern 0.0
11130 Fetching from uHunt 3.2k, Math Simulation, H mirror the billiard table to the right (and/or top) so that we will only deal with one straight line instead of bouncing... 0.0
11254 Fetching from uHunt 3.2k, Math Simulation, H use sum of AP; brute force all values of r from sqrt(2n) down to 1; stop at the first valid a 0.0
11490 Fetching from uHunt 3.2k, Math Simulation, H let missing_people = 2*a^2; thickness_of_soldiers = b; derive a formula involving a; b; and the given S 0.0
crackingrsa crackingrsa 3.2k, Math Simulation, H a bit number theory; solvable with complete search 258 2.3
falling falling 3.2k, Math Simulation, H rework the formula; complete search up to sqrt(D) 588 3.1
thanosthehero thanosthehero 3.2k, Math Simulation, H for-loop from backwards 320 3.9
00151 Fetching from uHunt 3.2l, Josephus Problem the original Josephus problem 0.0
01176 Fetching from uHunt 3.2l, Josephus Problem LA 2346 - Dhaka01; special case when k = 2; use Josephus recurrence; simulation 0.0
11351 Fetching from uHunt 3.2l, Josephus Problem use general case Josephus recurrence 0.0
eenymeeny eenymeeny 3.2l, Josephus Problem Josephus problem; small n; just simulate 492 1.7
musicalchairs musicalchairs 3.2l, Josephus Problem Josephus variant; brute force 139 4.0
toys toys 3.2l, Josephus Problem use general case Josephus recurrence 142 4.5
10344 Fetching from uHunt 3.2m, Backtracking, Easier 5 operands + 3 operators 0.0
10576 Fetching from uHunt 3.2m, Backtracking, Easier generate all; prune; take max 0.0
12840 Fetching from uHunt 3.2m, Backtracking, Easier simple backtracking 0.0
goodmorning goodmorning 3.2m, Backtracking, Easier we can use backtracking to generate all possible (small) numbers that can be pressed according to the constraints 347 2.7
lc0017 to replace with LeetCode link soon... 3.2m, Backtracking, Easier classic backtracking; leetcode-75; top-100-liked; top-interview-150 0 4.0
natjecanje natjecanje 3.2m, Backtracking, Easier 4 options for each team with kayak: do nothing, pass to left (if damaged), keep to self (if damaged), pass to right (if ... 701 2.5
paintings paintings 3.2m, Backtracking, Easier try all possible paintings based on Catherine's preference; skip hideous color pairs 162 3.6
00208 Fetching from uHunt 3.2n, Backtracking, Harder LA 5147 - WorldFinals SanAntonio91; backtracking with some pruning 0.0
00222 Fetching from uHunt 3.2n, Backtracking, Harder LA 5161 - WorldFinals Indianapolis93; cannot use DP 'tank' is floating-point; use backtracking 0.0
01262 Fetching from uHunt 3.2n, Backtracking, Harder LA 4845 - Daejeon10; sort grid columns; process common passwords in lexicographic order; skip two similar passwords 0.0
dobra dobra 3.2n, Backtracking, Harder try all possible 3^n changes of '_' (to a vowel, an 'L', or other consonant not 'L'); prune invalid states; count valid ... 44 3.9
fruitbaskets fruitbaskets 3.2n, Backtracking, Harder interesting backtracking problem; compute the small numbers < 200; output all minus this value computed via backtrack... 493 4.1
lc0216 to replace with LeetCode link soon... 3.2n, Backtracking, Harder backtracking; bitmask; generate solutions; leetcode-75 0 4.0
pagelayout pagelayout 3.2n, Backtracking, Harder a bit of geometry; O(2^n imes n^2 iterative bitmask will TLE; need to use recursive backtracking with pruning 84 5.1
11057 Fetching from uHunt 3.3a, Binary Search sort; target pair problem 0.0
11621 Fetching from uHunt 3.3a, Binary Search generate numbers with factor 2 and/or 3; sort; upper_bound 0.0
12965 Fetching from uHunt 3.3a, Binary Search sort producer/consumer prices; the answer is one of the prices mentioned; use binary searches to count the answer 0.0
firefly firefly 3.3a, Binary Search sort stalactites vs stalagmites separately; brute force height; binary search the obstacles hit 323 4.0
lc0162 to replace with LeetCode link soon... 3.3a, Binary Search interesting binary-search modification; leetcode-75; top-interview-150 0 4.0
outofsorts outofsorts 3.3a, Binary Search do O(log n) binary searches on unsorted array n times 107 3.7
roompainting roompainting 3.3a, Binary Search sort the cans at shop (can be used more than once); use lower_bound for what Joe needs at shop 416 3.8
12190 Fetching from uHunt 3.3b, Bisection and BSTA, E BSTA + algebra 0.0
13142 Fetching from uHunt 3.3b, Bisection and BSTA, E BSTA + Physics simulation 0.0
carefulascent carefulascent 3.3b, Bisection and BSTA, E BSTA + Physics simulation 558 1.8
freeweights freeweights 3.3b, Bisection and BSTA, E BSTA + simulation; Mathematical observation 356 4.5
lc0875 to replace with LeetCode link soon... 3.3b, Bisection and BSTA, E BSTA + simulation check; leetcode-75 0 4.0
monk monk 3.3b, Bisection and BSTA, E BSTA + simulation; cool 86 3.3
suspensionbridges suspensionbridges 3.3b, Bisection and BSTA, E BSTA + Maths; be careful of precision error 409 4.6
00183 Fetching from uHunt 3.3c, Ternary Search & Others simple exercise of DnC 0.0
10385 Fetching from uHunt 3.3c, Ternary Search & Others the function is unimodal; ternary search 0.0
12893 Fetching from uHunt 3.3c, Ternary Search & Others convert the given code into recursive DnC 0.0
a1paper a1paper 3.3c, Ternary Search & Others division of A1 paper is a kind of DnC principle 1212 3.9
ceiling ceiling 3.3c, Ternary Search & Others LA 7578 - WorldFinals Phuket16; BST insertion then tree equality check; also available at UVa 01738 - Ceiling Function 1871 1.9
goingtoseed goingtoseed 3.3c, Ternary Search & Others divide to search into four regions; extension of binary/ternary search concept 199 6.3
lc2293 to replace with LeetCode link soon... 3.3c, Ternary Search & Others simulate the game; n halves each level 0 2.0
01193 Fetching from uHunt 3.4a, Greedy (Classical) LA 2519 - Beijing02; interval covering 0.0
10020 Fetching from uHunt 3.4a, Greedy (Classical) interval covering 0.0
11264 Fetching from uHunt 3.4a, Greedy (Classical) coin change variant 0.0
classrooms classrooms 3.4a, Greedy (Classical) variant of interval covering; multiple rooms 229 5.9
froshweek2 froshweek2 3.4a, Greedy (Classical) greedy; sort first; similar to Dragon of Loowater; greedy matching 489 2.3
lc0455 to replace with LeetCode link soon... 3.4a, Greedy (Classical) sort; greedy bipartite matching 0 2.0
squarepegs squarepegs 3.4a, Greedy (Classical) convert square to circular; sort; greedy matching 265 3.1
11369 Fetching from uHunt 3.4b, Involving Sorting, E greedy; sorting 0.0
11900 Fetching from uHunt 3.4b, Involving Sorting, E greedy; sorting 0.0
13109 Fetching from uHunt 3.4b, Involving Sorting, E greedy; sorting 0.0
icpcteamselection icpcteamselection 3.4b, Involving Sorting, E greedy; sorting 586 3.0
lc1913 to replace with LeetCode link soon... 3.4b, Involving Sorting, E sort; use the last and first two 0 2.0
minimumscalar minimumscalar 3.4b, Involving Sorting, E one sort increasing; one sort decreasing 1202 2.3
shopaholic shopaholic 3.4b, Involving Sorting, E sort prices in descending order, pick every third item 959 2.4
lc0435 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort by non-decreasing endpoints; greedy; leetcode-75 0 4.0
lc0452 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort by non-decreasing endpoints; greedy; leetcode-75; top-interview-150 0 4.0
lc0881 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort people by non-dec weights; two pointers: lightest+heaviest; greedy 0 4.0
lc1090 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort by non-increasing values 0 4.0
lc1282 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort by non-decreasing size, keep the original indices 0 4.0
lc2895 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort tasks by non-increasing order and processor time by non-decreasing order 0 4.0
lc3301 to replace with LeetCode link soon... 3.4c, Involving Sorting, M sort by non-increasing maximum height 0 4.0
12673 Fetching from uHunt 3.4d, Involving Sorting, H LA 6530 - LatinAmerica13; greedy; sorting 0.0
12834 Fetching from uHunt 3.4d, Involving Sorting, H greedy; sorting 0.0
13054 Fetching from uHunt 3.4d, Involving Sorting, H greedy; sorting 0.0
airconditioned airconditioned 3.4d, Involving Sorting, H greedy; sorting 1116 3.9
birds birds 3.4d, Involving Sorting, H greedy; sorting 566 3.5
delivery delivery 3.4d, Involving Sorting, H sort, process positive and negative delivery separately; go to rightmost, come back and fill as many from the right 253 3.3
lc0055 to replace with LeetCode link soon... 3.4d, Involving Sorting, H for each reachable i, greedily extend the furthest jump, if we can; top-100-liked; top-interview-150 0 4.0
01153 Fetching from uHunt 3.4e, Involving PQ greedy; priority queue 0.0
13177 Fetching from uHunt 3.4e, Involving PQ greedy; priority queue 0.0
ballotboxes ballotboxes 3.4e, Involving PQ greedy; priority queue 776 4.4
canvas canvas 3.4e, Involving PQ PQ simulation; process from N canvases to 1 all-white canvas; take two minimum canvas size; greedy; add them and re-enqu... 214 3.5
lc2542 to replace with LeetCode link soon... 3.4e, Involving PQ sort (nums2[i], nums1[i]) by non-increasing nums2; maintain min PQ of nums1; keep largest k; leetcode-75 0 4.0
vegetables vegetables 3.4e, Involving PQ store cut lengths as fractions; keep taking the largest portion; greedy; try to cut 1/2,1/3,1/4,etc; re-enqueue the resu... 347 3.4
workstations workstations 3.4e, Involving PQ greedy; priority queue 1110 3.6
10656 Fetching from uHunt 3.4f, Non-Classical, Easier greedy 0.0
11520 Fetching from uHunt 3.4f, Non-Classical, Easier greedy 0.0
12482 Fetching from uHunt 3.4f, Non-Classical, Easier greedy 0.0
ants ants 3.4f, Non-Classical, Easier greedy; also available at UVa 10714 - Ants 1145 2.5
bank bank 3.4f, Non-Classical, Easier greedy 2389 2.6
lc0860 to replace with LeetCode link soon... 3.4f, Non-Classical, Easier use 10+5 before 5+5+5; programming-skills 0 2.0
marblestree marblestree 3.4f, Non-Classical, Easier greedy; also available at UVa 10672 - Marbles on a tree 258 3.0
10821 Fetching from uHunt 3.4g, Non-Classical, Harder greedy 0.0
11491 Fetching from uHunt 3.4g, Non-Classical, Harder greedy 0.0
11583 Fetching from uHunt 3.4g, Non-Classical, Harder greedy 0.0
11890 Fetching from uHunt 3.4g, Non-Classical, Harder greedy 0.0
dvds dvds 3.4g, Non-Classical, Harder greedy 731 2.9
lc0763 to replace with LeetCode link soon... 3.4g, Non-Classical, Harder DAT last occurence of ('a'..'z'); one-pass greedy solution is possible; top-100-liked 0 4.0
stockbroker stockbroker 3.4g, Non-Classical, Harder greedy 578 3.4
virus virus 3.4g, Non-Classical, Harder greedy 753 3.6
10684 Fetching from uHunt 3.5a, 1D Range Sum standard; Kadane's algorithm 0.0
commercials commercials 3.5a, 1D Range Sum transform each input by -P; Kadane's algorithm 1570 2.0
lc0053 to replace with LeetCode link soon... 3.5a, 1D Range Sum Kadane's; special case for all negatives; top-100-liked; top-interview-150 0 4.0
sellingspatulas sellingspatulas 3.5a, 1D Range Sum -8 per time slot initially; read sale data; 1D range sum; complete search 109 8.0
shortsell shortsell 3.5a, 1D Range Sum similar to Kadane's algorithm; linear pass; prefix sum 104 4.1
01105 Fetching from uHunt 3.5b, 2D Range Sum LA 5132 - WorldFinals Orlando11; more advanced 2D Range Sum Queries 0.0
10755 Fetching from uHunt 3.5b, 2D Range Sum max 2D range sum in 2 of the 3 dimensions; max 1D range sum with Kadane's algorithm on the 3rd dimension 0.0
lc0085 to replace with LeetCode link soon... 3.5b, 2D Range Sum after penalising the 0s heavily, this is just max 2D range sum 0 6.0
prozor prozor 3.5b, 2D Range Sum 2D range sum with fix range; output formatting 558 1.6
00481 Fetching from uHunt 3.5c, LIS O(n log k) LIS+solution 0.0
01196 Fetching from uHunt 3.5c, LIS LA 2815 - Kaohsiung03; sort all the blocks in increasing L[i]; then we get the classical LIS problem 0.0
11790 Fetching from uHunt 3.5c, LIS combination of LIS LDS; weighted 0.0
increasingsubsequence increasingsubsequence 3.5c, LIS LIS; n ≤ 200$; print lexicographically smallest solution, 99% similar to 'longincsubseq' 352 4.1
lc0334 to replace with LeetCode link soon... 3.5c, LIS LIS problem with a very small tweak; leetcode-75 0 4.0
nesteddolls nesteddolls 3.5c, LIS sort in one dimension; Dilworth's theorem; LIS in the other; also available at UVa 11368 - Nested Dolls 115 7.1
trainsorting trainsorting 3.5c, LIS max(LIS(i)+LDS(i)-1), ∀i ∈ [0...n-1]; also available at UVa 11456 522 5.4
01213 Fetching from uHunt 3.5d, 0-1 KNAPSACK/SS LA 3619 - Yokohama06; extension of 0-1 KNAPSACK; s: (id, remN, remK) instead of s: (id, remN) 0.0
10130 Fetching from uHunt 3.5d, 0-1 KNAPSACK/SS basic 0-1 Knapsack problem 0.0
11832 Fetching from uHunt 3.5d, 0-1 KNAPSACK/SS interesting DP; s: (id; val); use offset to handle negative numbers; t: plus or minus; print solution 0.0
knapsack knapsack 3.5d, 0-1 KNAPSACK/SS basic DP KNAPSACK; print the solution 687 4.8
lc0474 to replace with LeetCode link soon... 3.5d, 0-1 KNAPSACK/SS Knapsack; skip or take a string 0 4.0
orders orders 3.5d, 0-1 KNAPSACK/SS interesting KNAPSACK variant; print the solution 713 4.5
presidentialelections presidentialelections 3.5d, 0-1 KNAPSACK/SS pre-process the input to discard non winnable states; be careful of negative total voters; then standard DP KNAPSACK 116 5.7
00242 Fetching from uHunt 3.5e, COIN-CHANGE LA 5181 - WorldFinals Nashville95; Complete Search + DP Coin-Change 0.0
00674 Fetching from uHunt 3.5e, COIN-CHANGE basic coin change problem 0.0
11259 Fetching from uHunt 3.5e, COIN-CHANGE part of the problem is DP COIN-CHANGE with restricted number of coins per type; inclusion-exclusion 0.0
bagoftiles bagoftiles 3.5e, COIN-CHANGE count number of ways to do COIN-CHANGE; meet in the middle; DP combinatorics (n choose k) to find the answer for a+b 102 6.5
canonical canonical 3.5e, COIN-CHANGE complete search possible range of counter examples; do both greedy COIN-CHANGE and DP COIN-CHANGE 502 5.7
exactchange2 exactchange2 3.5e, COIN-CHANGE a variation to the Coin-Change problem; also available at UVa 11517 - Exact Change 708 5.4
lc0322 to replace with LeetCode link soon... 3.5e, COIN-CHANGE COIN-CHANGE; top-100-liked; top-interview-150 0 4.0
00216 Fetching from uHunt 3.5f, TSP LA 5155 - WorldFinals KansasCity92; DP TSP problem; but still solvable with backtracking 0.0
11795 Fetching from uHunt 3.5f, TSP DP TSP variant; counting paths on DAG; DP+bitmask; let Mega Buster owned by a dummy 'Robot 0' 0.0
12841 Fetching from uHunt 3.5f, TSP simply find and print the lexicographically smallest Hamiltonian path; use DP-TSP technique 0.0
beepers beepers 3.5f, TSP DP or recursive backtracking with sufficient pruning; also available at UVa 10496 - Collecting Beepers 196 4.6
bustour bustour 3.5f, TSP LA 6028 - WorldFinals Warsaw12; DP TSP variant; also available at UVa 01281 - Bus Tour 124 6.1
cycleseasy cycleseasy 3.5f, TSP Count number of HAMILTONIAN-TOURs 108 4.1
errands errands 3.5f, TSP map location names to integer indices; DP TSP 51 7.0
01261 Fetching from uHunt 3.5g, Non-Classical, 1D, E LA 4844 - Daejeon10; backtracking possible; but we use a set<string> to prevent recomputation 0.0
11420 Fetching from uHunt 3.5g, Non-Classical, 1D, E s: (prev; id; numlck); lock/unlock this chest 0.0
12654 Fetching from uHunt 3.5g, Non-Classical, 1D, E s: (hole); t: use patch T1 or patch T2 0.0
lc0746 to replace with LeetCode link soon... 3.5g, Non-Classical, 1D, E s: (i); t: to (i+1) or (i+2); Fibonacci variant; leetcode-75 0 2.0
10003 Fetching from uHunt 3.5h, Non-Classical, 2D, E discussed in this section 0.0
11450 Fetching from uHunt 3.5h, Non-Classical, 2D, E discussed in this section 0.0
13141 Fetching from uHunt 3.5h, Non-Classical, 2D, E s: (level, branch_previously); t: not branching if branch_previously or branching (one side) otherwise 0.0
nikola nikola 3.5h, Non-Classical, 2D, E s: (pos, last_jump); t: jump forward or backward 295 3.6
spiderman spiderman 3.5h, Non-Classical, 2D, E simple DP; go up or down; print solution 1010 3.9
ticketpricing ticketpricing 3.5h, Non-Classical, 2D, E LA 6867 - Rocky Mountain15; similar with UVa 11450 discussed in this book; real life problem; print (the first) part of ... 138 4.9
12324 Fetching from uHunt 3.5i, DP level 2 spheres > n are useless 0.0
12862 Fetching from uHunt 3.5i, DP level 2 1D DP to compute the path cost from every vertex that goes up to the mountain top; compute answer 0.0
12955 Fetching from uHunt 3.5i, DP level 2 there are only 8 eligible factorials under 100000; we can use DP; s: (i, sum); t: take/stay, take/move, don't take/move 0.0
kutevi kutevi 3.5i, DP level 2 s: (360 integer degrees) 170 2.6
lc0714 to replace with LeetCode link soon... 3.5i, DP level 2 s: (own, i); t: skip day i or sell if own/buy if not; leetcode-75 0 4.0
tight tight 3.5i, DP level 2 s: (i, j); #tight words of length i that end in digit j divided by #words: (k+1)^n; also available at UVa 10081 - Tight ... 100 3.5
walrusweights walrusweights 3.5i, DP level 2 backtracking with memoization 570 3.8
11749 Fetching from uHunt 4.2a, Finding CCs find the largest CC with highest average PPA; also solvable with UFDS 0.0
11906 Fetching from uHunt 4.2a, Finding CCs DFS/BFS for reachability; several tricky cases; be careful when M = 0; N = 0; or M = N 0.0
lc0547 to replace with LeetCode link soon... 4.2a, Finding CCs count number of CCs; leetcode-75 0 4.0
reachableroads reachableroads 4.2a, Finding CCs report number of CC-1 892 2.1
securitybadge securitybadge 4.2a, Finding CCs reachability test; clever idea to compress ids 129 7.6
terraces terraces 4.2a, Finding CCs group cells with similar height together; if it cannot flow to any other component with lower height, add the size of th... 339 3.6
wheresmyinternet wheresmyinternet 4.2a, Finding CCs check connectivity to vertex 1 1716 3.7
00352 Fetching from uHunt 4.2b, Flood Fill, Easier count number of CCs; see UVa 00572 0.0
11953 Fetching from uHunt 4.2b, Flood Fill, Easier interesting twist of flood fill problem 0.0
amoebas amoebas 4.2b, Flood Fill, Easier easy floodfill 1079 1.8
countingstars countingstars 4.2b, Flood Fill, Easier basic flood fill problem; count CCs 1494 2.7
fontan fontan 4.2b, Flood Fill, Easier modified multi-sources BFS/floodfill 866 2.0
gold gold 4.2b, Flood Fill, Easier flood fill with extra blocking constraint; also available at UVa 11561 - Getting Gold 735 2.2
lc0733 to replace with LeetCode link soon... 4.2b, Flood Fill, Easier basic flood fill problem 0 2.0
01103 Fetching from uHunt 4.2c, Flood Fill, Harder LA 5130 - WorldFinals Orlando11; major hint: each hieroglyph has unique number of white CCs 0.0
10kindsofpeople 10kindsofpeople 4.2c, Flood Fill, Harder intelligent flood fill; just run once to avoid TLE as there are many queries 2380 3.9
11585 Fetching from uHunt 4.2c, Flood Fill, Harder polynomial-time verifier for an NP-complete puzzle Nurikabe; this verifier requires clever usage of flood fill algorithm 0.0
coast coast 4.2c, Flood Fill, Harder intelligent flood fill; just run once to avoid TLE as there are many queries 1339 3.2
islands3 islands3 4.2c, Flood Fill, Harder optimistic flood fill; assume all Cs are Ls 936 2.1
lc1254 to replace with LeetCode link soon... 4.2c, Flood Fill, Harder flood fill; avoiding borders 0 4.0
00872 Fetching from uHunt 4.2d, Topological Sort similar to UVa 00124; use backtracking 0.0
11060 Fetching from uHunt 4.2d, Topological Sort Kahn's algorithm---modified BFS toposort 0.0
brexit brexit 4.2d, Topological Sort toposort; chain reaction; modified Kahn's algorithm 826 3.6
builddeps builddeps 4.2d, Topological Sort the graph is acyclic; toposort with DFS from the changed file 626 4.7
conservation conservation 4.2d, Topological Sort modified Kahn's algorithm; greedily process all steps in a certain lab before alternating to the other lab 133 4.2
lc0210 to replace with LeetCode link soon... 4.2d, Topological Sort cycle check; compute toposort if acyclic; top-interview-150 0 4.0
pickupsticks pickupsticks 4.2d, Topological Sort cycle check + toposort if DAG; also available at item UVa 11686 - Pick up sticks 373 4.7
10116 Fetching from uHunt 4.2e, Graph Properties Check traversal on implicit graph; cycle check 0.0
10505 Fetching from uHunt 4.2e, Graph Properties Check bipartite; take max(left; right) 0.0
hoppers hoppers 4.2e, Graph Properties Check the answer is number of CC-1 if there is at least one non-bipartite component in the graph; or number of CC otherwise 234 3.9
lc0207 to replace with LeetCode link soon... 4.2e, Graph Properties Check is the directed graph acyclic?; top-100-liked; top-interview-150 0 4.0
molekule molekule 4.2e, Graph Properties Check undirected tree is also Bipartite/bi-colorable; bi-color it with 0 and 1; direct all edges from 0 to 1 (or vice versa) 175 3.5
runningmom runningmom 4.2e, Graph Properties Check find a cycle in a directed graph 591 3.8
torn2pieces torn2pieces 4.2e, Graph Properties Check construct graph from strings; traversal from source to target; reachability check; print path 1115 3.6
10765 Fetching from uHunt 4.2f, Cut Vertices/Bridges finding articulation points 0.0
12363 Fetching from uHunt 4.2f, Cut Vertices/Bridges LA 5796 - Latin America; transform input to graph of its bridges; see if b is reachable from a with only the bridges 0.0
12783 Fetching from uHunt 4.2f, Cut Vertices/Bridges finding bridges 0.0
birthday birthday 4.2f, Cut Vertices/Bridges check if the input graph contains any bridge; N is small though so weaker solution can still be accepted 323 4.3
caveexploration caveexploration 4.2f, Cut Vertices/Bridges find size of bi-connected components that contains vertex 0; identify the bridges 848 3.3
gymleadersterritory gymleadersterritory 4.2f, Cut Vertices/Bridges if all edges connected to vertex k are bridges, then `YES`; otherwise `NO` 165 3.5
intercept intercept 4.2f, Cut Vertices/Bridges Articulation Points in SSSP Spanning DAG; clever modification of Dijkstra's 112 6.6
00247 Fetching from uHunt 4.2g, Finding SCCs SCC + printing solution 0.0
11709 Fetching from uHunt 4.2g, Finding SCCs find the number of SCCs 0.0
11770 Fetching from uHunt 4.2g, Finding SCCs similar to UVa 11504 0.0
cantinaofbabel cantinaofbabel 4.2g, Finding SCCs build directed graph 'can_speak'; compute the largest SCC of 'can_speak'; keep this largest SCC 1294 3.2
dominos dominos 4.2g, Finding SCCs count the number of SCCs without incoming edge from a vertex outside that SCC; also available at UVa 11504 - Dominos 248 6.2
equivalences equivalences 4.2g, Finding SCCs contract input directed graph into SCCs; count SCCs that have in-/out-degrees = 0; report the max 281 5.4
reversingroads reversingroads 4.2g, Finding SCCs if #SCC = 1, print 'valid'; or try reversing one of the m directed edges until we either have #SCC = 1, or print 'invali... 640 3.7
11831 Fetching from uHunt 4.2h, Really Ad Hoc traversal on implicit graph 0.0
12442 Fetching from uHunt 4.2h, Really Ad Hoc modified DFS; special graph 0.0
dominoes2 dominoes2 4.2h, Really Ad Hoc unlike UVa 11504, we treat SCCs as CCs; also available at UVa 11518 - Dominos 2 599 3.3
faultyrobot faultyrobot 4.2h, Really Ad Hoc interesting graph traversal variant; add one more state to each vertex: bug_used 556 3.6
lc0841 to replace with LeetCode link soon... 4.2h, Really Ad Hoc DFS/BFS from 0; see if all rooms are visited; leetcode-75 0 4.0
promotions promotions 4.2h, Really Ad Hoc modified DFS; special graph; DAG; also available at UVa 13015 - Promotions 129 5.5
succession succession 4.2h, Really Ad Hoc (upwards) traversal of family DAG; use unordered_maps; make the founder has very large starting blood to avoid fraction 165 3.1
11631 Fetching from uHunt 4.3a, MST, Standard weight of (all graph edges - all MST edges) 0.0
11747 Fetching from uHunt 4.3a, MST, Standard sum the edge weights of the chords 0.0
cats cats 4.3a, MST, Standard standard MST 456 4.1
islandhopping islandhopping 4.3a, MST, Standard MST on small complete graph 440 3.0
lc1584 to replace with LeetCode link soon... 4.3a, MST, Standard basic MST problem 0 4.0
lostmap lostmap 4.3a, MST, Standard actually just a standard MST problem 782 2.1
minspantree minspantree 4.3a, MST, Standard very standard MST problem; check if a spanning tree is formed; also output the edges in any spanning tree in lexicograph... 862 4.0
01013 Fetching from uHunt 4.3b, MST, Variants LA 2478 - WorldFinals Honolulu02; very interesting MST variant 0.0
01265 Fetching from uHunt 4.3b, MST, Variants LA 4848 - Daejeon10; very interesting non-standard variant of 'maximum' spanning tree 0.0
10457 Fetching from uHunt 4.3b, MST, Variants interesting MST modeling 0.0
millionairemadness millionairemadness 4.3b, MST, Variants MiniMax path problem 649 2.4
muddyhike muddyhike 4.3b, MST, Variants MiniMax path problem 209 3.9
naturereserve naturereserve 4.3b, MST, Variants Prim's algorithm from multiple sources 180 4.6
10653 Fetching from uHunt 4.4a, SSSP, BFS, Easier need efficient BFS implementation 0.0
12160 Fetching from uHunt 4.4a, SSSP, BFS, Easier LA 4408 - KualaLumpur08; s: (4-digits number); edges: button pushes; BFS 0.0
buttonbashing buttonbashing 4.4a, SSSP, BFS, Easier very similar to UVa 12160 728 3.4
horror horror 4.4a, SSSP, BFS, Easier SSSP from all sources = horror movies; report lowest ID with the highest unweighted SSSP distance 500 3.3
11352 Fetching from uHunt 4.4b, SSSP, BFS, Medium filter the graph first; then it becomes SSSP 0.0
12826 Fetching from uHunt 4.4b, SSSP, BFS, Medium SSSP from (r1; c1) to (r2; c2) avoiding (r3; c3); BFS 0.0
fire2 fire2 4.4b, SSSP, BFS, Medium very similar to UVa 11624 395 4.2
lc1926 to replace with LeetCode link soon... 4.4b, SSSP, BFS, Medium BFS on grid; stop at border (that is not source); leetcode-75 0 4.0
lost lost 4.4b, SSSP, BFS, Medium interesting twist of BFS/SSSP spanning tree 269 4.7
mallmania mallmania 4.4b, SSSP, BFS, Medium multi-sources BFS from m1; get minimum at border of m2; also available at UVa 11101 - Mall Mania 48 4.9
oceancurrents oceancurrents 4.4b, SSSP, BFS, Medium 0/1-weighted SSSP; BFS+deque; also available at UVa 11573 - Ocean Currents 118 5.4
00439 Fetching from uHunt 4.4c, Knight Moves, BFS one BFS per query is enough 0.0
10426 Fetching from uHunt 4.4c, Knight Moves, BFS for each knight, do BFS when the monster is sleep/awake; try: one awake the monster, the rest go around 0.0
10477 Fetching from uHunt 4.4c, Knight Moves, BFS s: (row; col; knight_state); implicit unweighted graph; different edges per different knight_state 0.0
grasshopper grasshopper 4.4c, Knight Moves, BFS BFS on implicit Knight jump graph 136 4.0
hidingplaces hidingplaces 4.4c, Knight Moves, BFS SSSP from (r, c); find cells with max distance; print 607 1.9
lc2596 to replace with LeetCode link soon... 4.4c, Knight Moves, BFS standard knight tour; BFS; 8 directions 0 4.0
01112 Fetching from uHunt 4.4e, SSSP, Dijkstra, Easier LA 2425 - SouthwesternEurope01; SDSP 0.0
13127 Fetching from uHunt 4.4e, SSSP, Dijkstra, Easier Dijkstra's from multiple sources 0.0
flowerytrails flowerytrails 4.4e, SSSP, Dijkstra, Easier Dijkstra's; record predecessor graph as there can be multiple shortest paths; also available at UVa 12878 - Flowery Trai... 305 3.9
shortestpath1 shortestpath1 4.4e, SSSP, Dijkstra, Easier very standard Dijkstra's problem 1470 3.5
shortestpath2 shortestpath2 4.4e, SSSP, Dijkstra, Easier Dijkstra's with modification; edges only available periodically; be careful with P = 0 case 423 3.9
texassummers texassummers 4.4e, SSSP, Dijkstra, Easier Dijkstra's; complete weighted graph; print path 97 4.0
00589 Fetching from uHunt 4.4g, SSSP, Dijkstra, Harder weighted SSSP: move box from s to t + unweighted SSSP: move player to correct position to push the box 0.0
12047 Fetching from uHunt 4.4g, SSSP, Dijkstra, Harder clever usage of Dijkstra's; run Dijkstra's from source and from d from destination 0.0
12950 Fetching from uHunt 4.4g, SSSP, Dijkstra, Harder clever usage of Dijstra's; instead of extending by one edge, we can extend by two edges at a time 0.0
blockcrusher blockcrusher 4.4g, SSSP, Dijkstra, Harder Dijkstra's from top row to bottom row (or vice versa); print path 257 5.1
emptyingbaltic emptyingbaltic 4.4g, SSSP, Dijkstra, Harder Dijkstra's variant; grow spanning tree from drain/source 287 5.4
invasion invasion 4.4g, SSSP, Dijkstra, Harder SSSP with multiple and successive sources; multiple calls of Dijkstra's (gets lighter each time if pruned properly) 46 4.3
visualgo visualgo 4.4g, SSSP, Dijkstra, Harder Dijkstra's produces SSSP spanning DAG if there are multiple shortest paths from s to t; counting paths on DAG 496 3.4
00558 Fetching from uHunt 4.4h, SSSP, Bellman-Ford check if negative cycle exists 0.0
10449 Fetching from uHunt 4.4h, SSSP, Bellman-Ford find the minimum weight path; which may be negative; be careful: INF negative weight is lower than INF 0.0
12768 Fetching from uHunt 4.4h, SSSP, Bellman-Ford insert -F as edge weight; see if negative cycle exists; or find min SSSP value from s = 1 0.0
hauntedgraveyard hauntedgraveyard 4.4h, SSSP, Bellman-Ford Bellman-Ford; negative cycle check needed 95 8.2
lc0743 to replace with LeetCode link soon... 4.4h, SSSP, Bellman-Ford SSSP on a small directed weighted graph 0 4.0
shortestpath3 shortestpath3 4.4h, SSSP, Bellman-Ford Bellman-Ford; do DFS/BFS from vertices that are part of any negative cycle 524 5.1
xyzzy xyzzy 4.4h, SSSP, Bellman-Ford check 'positive' cycle; check connectedness; also available at UVa 10557 152 6.7
00821 Fetching from uHunt 4.5a, APSP, Standard LA 5221 - WorldFinals Orlando00; one of the easiest ICPC WorldFinals problem 0.0
01247 Fetching from uHunt 4.5a, APSP, Standard LA 4524 - Hsinchu09; Floyd-Warshall with modification: prefer shortest path with less intermediate vertices 0.0
10354 Fetching from uHunt 4.5a, APSP, Standard find and remove edges involved in boss's shortest paths; re-run shortest paths from home to market 0.0
allpairspath allpairspath 4.5a, APSP, Standard basic Floyd-Warshall; tricky negative cycle checks 772 5.5
importspaghetti importspaghetti 4.5a, APSP, Standard smallest cycle; print path by breaking the self-loop into i - other vertex j - i 292 5.1
lc1334 to replace with LeetCode link soon... 4.5a, APSP, Standard get APSP information using Floyd-Warshall; compute reachability; get the answer 0 4.0
transportationplanning transportationplanning 4.5a, APSP, Standard APSP; FW; for each unused edge, use it and see how much distance is reduced; get minimum; O(n^4) 65 3.9
01056 Fetching from uHunt 4.5b, APSP, Variants LA 3569 - WorldFinals SanAntonio06; finding diameter of a small graph with Floyd-Warshall 0.0
10342 Fetching from uHunt 4.5b, APSP, Variants Floyd-Warshall to get APSP values; to get the second best shortest path, try to make a single mistake 0.0
10987 Fetching from uHunt 4.5b, APSP, Variants creative usage of Floyd-Warshall algorithm; if we can detour without increasing cost, then delete the direct edge 0.0
arbitrage arbitrage 4.5b, APSP, Variants arbitrage problem; similar to UVa 00104 and 00436 324 3.3
kastenlauf kastenlauf 4.5b, APSP, Variants n ≤ 100; Warshall's transitive closure problem 713 3.8
secretchamber secretchamber 4.5b, APSP, Variants LA 8047 - WorldFinals RapidCity17; Warshall's transitive closure; also available at UVa 01757 - Secret Chamber ... 1187 2.2
00452 Fetching from uHunt 4.6a, S/Longest Paths on DAG LONGEST-PATH on DAG 0.0
10350 Fetching from uHunt 4.6a, S/Longest Paths on DAG shortest paths; implicit DAG; DP 0.0
fibtour fibtour 4.6a, S/Longest Paths on DAG only ~90 Fibonacci numbers not more than 10^18; LONGEST-PATH on DAG problem; special case for first two Fibonacci number... 105 6.4
lc0064 to replace with LeetCode link soon... 4.6a, S/Longest Paths on DAG basic SSSP on DAG; top-100-liked; top-interview-150 0 4.0
mravi mravi 4.6a, S/Longest Paths on DAG reverse edge directions to change the input tree into a DAG; find longest path from leaf that contains ant to root 197 2.7
safepassage safepassage 4.6a, S/Longest Paths on DAG SSSP; implicit DAG; s: (cloak_pos, bitmask); try all ways to go back and forth between gate and dorm; report minimum 387 4.9
10544 Fetching from uHunt 4.6b, Counting Paths, Easier counting paths in implicit DAG 0.0
11569 Fetching from uHunt 4.6b, Counting Paths, Easier determine the length of one of the longest paths and then count the number of such longest paths in DAG 0.0
compositions compositions 4.6b, Counting Paths, Easier LA 7365 - Greater NY15; s: (N_left); t: try all values, skip some numbers 160 2.3
lc0062 to replace with LeetCode link soon... 4.6b, Counting Paths, Easier counting paths; DAG; leetcode-75; top-100-liked 0 4.0
robotsonagrid robotsonagrid 4.6b, Counting Paths, Easier counting paths in implicit DAG 147 4.3
runningsteps runningsteps 4.6b, Counting Paths, Easier LA 7360 - Greater NY15; s: (leg, l2, r2, l1, r1); t: left/right leg 1/2 steps; use unordered_map as memo table; use prun... 168 2.6
scenes scenes 4.6b, Counting Paths, Easier s: (pos, ribbon_left); t: try all possible heights; ignore the flat scenes first and subtract those cases at the end 407 3.6
00590 Fetching from uHunt 4.6c, Conversion to DAG s: (pos; day_left) 0.0
10913 Fetching from uHunt 4.6c, Conversion to DAG s: (r; c; neg_left; stat); t: down/(left/right) 0.0
12875 Fetching from uHunt 4.6c, Conversion to DAG LA 6853 - Bangkok14; similar to UVa 10702; s: (cur_store; cur_concert); t: pick any next store for next concert 0.0
cardmagic cardmagic 4.6c, Conversion to DAG s: (deck, tgt_left); t: val 1 to K ≤ tgt_left 133 3.9
drinkresponsibly drinkresponsibly 4.6c, Conversion to DAG s: (cur_drink, money_left, u_left); be careful with precision errors; print solution 98 4.2
maximizingwinnings maximizingwinnings 4.6c, Conversion to DAG separate the maximizing and minimizing problem; s: (cur_room, turns_left); t: go to other room or stay 193 3.9
00536 Fetching from uHunt 4.6d, Tree reconstructing binary tree from preorder and inorder binary tree traversal 0.0
11695 Fetching from uHunt 4.6d, Tree cut the worst edge along the tree diameter; link two centers; also available at Kattis - flight 0.0
12347 Fetching from uHunt 4.6d, Tree given pre-order traversal of a BST; use BST property to get the BST; output the post-order traversal that BST 0.0
12379 Fetching from uHunt 4.6d, Tree find the diameter of tree first; we only traverse the diameter once and we traverse the other edges twice 0.0
adjoin adjoin 4.6d, Tree the key parts are finding tree diameter and its center (along that diameter); also see UVa 11695 373 5.3
flight flight 4.6d, Tree cut the worst edge along the tree diameter; link two centers; also available at UVa 11695 - Flight Planning 46 6.3
lc1466 to replace with LeetCode link soon... 4.6d, Tree create undirected tree; traverse from the root 0 to identify the answers; leetcode-75 0 4.0
tourists tourists 4.6d, Tree APSP on Tree (special requirements); LCA 431 3.8
00670 Fetching from uHunt 4.6e, Bipartite Graph MCBM 0.0
11138 Fetching from uHunt 4.6e, Bipartite Graph a pure MCBM problem 0.0
12644 Fetching from uHunt 4.6e, Bipartite Graph classic MCBM problem wrapped inside a creative problem statement 0.0
12668 Fetching from uHunt 4.6e, Bipartite Graph LA 6525 - LatinAmerica13; split rows/columns due to the presence of pawns; then run MCBM 0.0
bookclub bookclub 4.6e, Bipartite Graph check if perfect MCBM is possible 307 4.5
escapeplan escapeplan 4.6e, Bipartite Graph left set: robots; right set: holes; 3 version of similar bipartite graphs; MCBM 98 5.7
flippingcards flippingcards 4.6e, Bipartite Graph left set: n card numbers; right set: 2*n picture numbers; possible if MCBM = n; need fast algorithm 169 7.0
00291 Fetching from uHunt 4.6f, Eulerian Graph Euler tour on a small graph; backtracking is sufficient 0.0
10054 Fetching from uHunt 4.6f, Eulerian Graph printing the Euler tour 0.0
10203 Fetching from uHunt 4.6f, Eulerian Graph the underlying graph is Euler graph 0.0
10596 Fetching from uHunt 4.6f, Eulerian Graph Euler Graph property check 0.0
catenyms catenyms 4.6f, Eulerian Graph Euler graph property check; 26 vertices; directed non simple graph; printing the Euler tour in lexicographic order 67 7.1
eulerianpath eulerianpath 4.6f, Eulerian Graph Euler graph property check; directed graph; printing the Euler tour 219 5.6
railroad2 railroad2 4.6f, Eulerian Graph x-shaped level junctions have even degrees - ignore X; y-shaped switches have degree 3 - Y has to be even 2188 1.4
lc0102 to replace with LeetCode link soon... 4.6g, BT Exercises, H BFS; expand frontier; top-100-liked; top-interview-150 0 4.0
lc0111 to replace with LeetCode link soon... 4.6g, BT Exercises, H BFS until there is a leaf 0 2.0
lc0199 to replace with LeetCode link soon... 4.6g, BT Exercises, H BFS; last item per level; leetcode-75; top-100-liked; top-interview-150 0 4.0
lc0429 to replace with LeetCode link soon... 4.6g, BT Exercises, H BFS on n-ary tree 0 4.0
lc1161 to replace with LeetCode link soon... 4.6g, BT Exercises, H BFS; max level sum; leetcode-75 0 4.0
lc1609 to replace with LeetCode link soon... 4.6g, BT Exercises, H BFS; with custom ordering rules 0 4.0
12004 Fetching from uHunt 5.2a, Finding Formula, Easier try small n; get the pattern; use long long 0.0
12918 Fetching from uHunt 5.2a, Finding Formula, Easier sum of arithmetic progression; long long 0.0
averageshard averageshard 5.2a, Finding Formula, Easier find O(n) formula; also see Kattis - averageseasy 605 2.6
bishops bishops 5.2a, Finding Formula, Easier chess pattern involving bishops; from IPSC 2004 1185 2.2
crne crne 5.2a, Finding Formula, Easier simulate cutting process on small numbers; get formula 477 2.5
lc1523 to replace with LeetCode link soon... 5.2a, Finding Formula, Easier simple formula; inclusion-exclusion; programming-skills 0 2.0
lc2413 to replace with LeetCode link soon... 5.2a, Finding Formula, Easier a simple number theory; n or 2n 0 2.0
twostones twostones 5.2a, Finding Formula, Easier just check odd or even 15317 1.3
10161 Fetching from uHunt 5.2b, Finding Formula, Harder sqrt and ceil 0.0
11038 Fetching from uHunt 5.2b, Finding Formula, Harder define a function f that counts the number of 0s from 1 to n; also available at Kattis - howmanyzeros 0.0
11718 Fetching from uHunt 5.2b, Finding Formula, Harder convert loops to a closed form formula; use modPow to compute the results 0.0
lc0781 to replace with LeetCode link soon... 5.2b, Finding Formula, Harder count the answer frequencies; for each answer k, group the rabbits into size k+1 0 4.0
mortgage mortgage 5.2b, Finding Formula, Harder geometric progression; divergent but finite; special case when r = 1.0 (no interest) 51 7.9
neighborhoodwatch neighborhoodwatch 5.2b, Finding Formula, Harder sum of AP; inclusion-exclusion 319 3.1
nine nine 5.2b, Finding Formula, Harder find the required formula 681 3.2
00389 Fetching from uHunt 5.2c, Base Number Conversion use Java Integer class 0.0
11952 Fetching from uHunt 5.2c, Base Number Conversion check base 2 to 18; special case for base 1 0.0
allaboutthatbase allaboutthatbase 5.2c, Base Number Conversion check base 1 to 36; base 1 is special; Big Integer 927 2.9
arithmetic arithmetic 5.2c, Base Number Conversion conversion of octal (per 4 bits) to hexa (per 3 bits); be careful with leading zeroes 726 3.9
basicremains basicremains 5.2c, Base Number Conversion also involving Big Integer modulo; also available at UVa 10551 - Basic Remains 174 3.4
lc0067 to replace with LeetCode link soon... 5.2c, Base Number Conversion convert a and b from bin to dec; add them; convert back; programming-skills; top-interview-150 0 2.0
oktalni oktalni 5.2c, Base Number Conversion convert each 3-bits of binary strings to octal; Big Integer 634 1.8
00575 Fetching from uHunt 5.2d, Base Number Variants base modification 0.0
10931 Fetching from uHunt 5.2d, Base Number Variants convert decimal to binary; count number of 1s 0.0
11121 Fetching from uHunt 5.2d, Base Number Variants search for the term 'negabinary' 0.0
aliennumbers aliennumbers 5.2d, Base Number Variants source base to decimal; decimal to target base 1050 2.1
ignore ignore 5.2d, Base Number Variants actually a base 7 conversion problem as only 7 digits are meaningful when rotated 268 3.2
lc2595 to replace with LeetCode link soon... 5.2d, Base Number Variants convert n from base 10 to 2; process 0 2.0
mixedbasearithmetic mixedbasearithmetic 5.2d, Base Number Variants mix of base 10 and two versions of base 26 54 5.9
00443 Fetching from uHunt 5.2e, Number Systems/Seqs try all 2^i * 3^j * 5^k * 7^l; sort 0.0
11970 Fetching from uHunt 5.2e, Number Systems/Seqs square numbers; divisibility; brute force 0.0
candlebox candlebox 5.2e, Number Systems/Seqs sum of arithmetic series [1..N]; -6 for Rita or -3 for Theo; brute force Rita's age; also available at UVa 13161 - Candl... 448 2.6
collatz collatz 5.2e, Number Systems/Seqs similar to UVa 00694; just do as asked 757 3.7
lc3099 to replace with LeetCode link soon... 5.2e, Number Systems/Seqs compute sum of digits; check as asked 0 2.0
permutedarithmeticsequence permutedarithmeticsequence 5.2e, Number Systems/Seqs sort differences of adjacent items 1262 2.0
rationalsequence rationalsequence 5.2e, Number Systems/Seqs pattern finding; tree traversal on a special tree 458 4.6
11384 Fetching from uHunt 5.2f, Log, Exp, Pow find the smallest power of two greater than n; can be solved easily using ceil(eps log2(n)) 0.0
11847 Fetching from uHunt 5.2f, Log, Exp, Pow O(1) math formula exists: floor(log2(n)) 0.0
cokolada cokolada 5.2f, Log, Exp, Pow the answers involve powers of two and a simulation 605 2.2
factstone factstone 5.2f, Log, Exp, Pow use logarithm; power; also available at UVa 10916 - Factstone Benchmark 200 3.6
lc0231 to replace with LeetCode link soon... 5.2f, Log, Exp, Pow n ≤ 0 is False; log2 and exp test 0 2.0
lemonadetrade lemonadetrade 5.2f, Log, Exp, Pow use log transformation technique; linear pass 82 5.3
thebackslashproblem thebackslashproblem 5.2f, Log, Exp, Pow actually power of two 349 2.2
00264 Fetching from uHunt 5.2g, Grid grid; pattern 0.0
10022 Fetching from uHunt 5.2g, Grid this is not an SSSP problem; find the pattern in this grid (triangle)-like system 0.0
10182 Fetching from uHunt 5.2g, Grid grid 0.0
10233 Fetching from uHunt 5.2g, Grid the number of items in row forms arithmetic progression series; use hypot 0.0
beehouseperimeter beehouseperimeter 5.2g, Grid transform the hexagonal grid like Kattis - honeyheist; flood fill from outside Alice's house; count #walls touched 155 4.0
honeyheist honeyheist 5.2g, Grid transform the hexagonal grid input into 2D grid first; then run SSSP on unweighted graph; BFS 135 3.8
maptiles2 maptiles2 5.2g, Grid simple conversion between two grid indexing systems 1338 1.6
00930 Fetching from uHunt 5.2h, Polynomial Ruffini's rule; roots of quadratic eq 0.0
10268 Fetching from uHunt 5.2h, Polynomial polynomial derivation; Horner's rule 0.0
10302 Fetching from uHunt 5.2h, Polynomial use long double 0.0
10586 Fetching from uHunt 5.2h, Polynomial compute number of prime factors of each integer in the desired range; use 1D RSQ DP; binary search 0.0
ada ada 5.2h, Polynomial polynomial problem; apply the given procedure recursively 346 2.8
curvyblocks curvyblocks 5.2h, Polynomial differentiate degree 3 to degree 2 polynomial; get roots of quadratic equation; the two blocks will touch at either root... 89 4.3
plot plot 5.2h, Polynomial analyze the given pseudocode; the required pattern involves Binomial Coefficients 210 2.5
00332 Fetching from uHunt 5.2i, Fractions use GCD 0.0
00834 Fetching from uHunt 5.2i, Fractions do as asked 0.0
12068 Fetching from uHunt 5.2i, Fractions involving fraction; use LCM and GCD 0.0
deadfraction deadfraction 5.2i, Fractions try every single possible repeating decimals; also available at UVa 10555 - Dead Fraction 153 4.9
fraction fraction 5.2i, Fractions continued fraction to normal fraction and vice versa 154 3.8
mixedfractions mixedfractions 5.2i, Fractions convert fraction to mixed fraction 5154 1.5
thermostat thermostat 5.2i, Fractions convert one temperature to another; use fraction; use Java BigInteger; gcd 81 3.4
00496 Fetching from uHunt 5.2j, Really Ad Hoc set manipulation 0.0
11241 Fetching from uHunt 5.2j, Really Ad Hoc the hardest case is computing Dew point given temperature and Humidex; derive it with Algebra 0.0
12036 Fetching from uHunt 5.2j, Really Ad Hoc use pigeon hole principle 0.0
lc0598 to replace with LeetCode link soon... 5.2j, Really Ad Hoc keep the largest upper-left rectangle size 0 2.0
matrix matrix 5.2j, Really Ad Hoc use simple linear algebra; one special case when c = 0 784 3.1
trip trip 5.2j, Really Ad Hoc be careful with precision error; also available at UVa 10137 - The Trip 103 5.5
yoda yoda 5.2j, Really Ad Hoc ad hoc; 9 digits comparison 1607 2.1
00543 Fetching from uHunt 5.3a, Prime Numbers sieve; complete search; Goldbach's conjecture; similar to UVa 00686, 10311, and 10948 0.0
01644 Fetching from uHunt 5.3a, Prime Numbers LA 3883 - Tokyo07; sieve; prime check; upper bound - lower bound 0.0
10650 Fetching from uHunt 5.3a, Prime Numbers 3 uni-distance consecutive primes 0.0
enlarginghashtables enlarginghashtables 5.3a, Prime Numbers use sieve up to 40 000; prime test numbers greater than 2n; check primality of n itself 448 3.4
primesieve primesieve 5.3a, Prime Numbers use sieve up to 10^8; it is fast enough 865 4.5
reseto reseto 5.3a, Prime Numbers sieve of Eratosthenes until the k-th crossing 460 2.7
01180 Fetching from uHunt 5.3b, (Prob) Prime Testing LA 2350 - Dhaka01; small prime check 0.0
01210 Fetching from uHunt 5.3b, (Prob) Prime Testing LA 3399 - Tokyo05; simple 0.0
flowergarden flowergarden 5.3b, (Prob) Prime Testing Euclidean dist; small prime check; use isProbablePrime; simulation; faster solutions exist 317 4.4
goldbach2 goldbach2 5.3b, (Prob) Prime Testing simple brute force problem; use isProbablePrime; faster solutions exist 1219 2.7
lc2614 to replace with LeetCode link soon... 5.3b, (Prob) Prime Testing check primes (Java isProbablePrime works) along the diagonals 0 2.0
primes2 primes2 5.3b, (Prob) Prime Testing convert input to either base 2/8/10/16; skip those that cause NumberFormatException error; use isProbablePrime test and ... 289 4.7
pseudoprime pseudoprime 5.3b, (Prob) Prime Testing yes if !isPrime(p) && a.modPow(p, p) = a; Big Integer; also available at UVa 11287 - Pseudoprime Numbers 347 3.5
00583 Fetching from uHunt 5.3c, Finding Prime Factors basic factorization problem 0.0
11466 Fetching from uHunt 5.3c, Finding Prime Factors use efficient sieve implementation to get the largest prime factors 0.0
12703 Fetching from uHunt 5.3c, Finding Prime Factors uses small Fibonacci numbers up to 40 and simple prime factorization as a and b can be non-primes 0.0
12805 Fetching from uHunt 5.3c, Finding Prime Factors prime check; primes of format 4m-1 and 4m plus 1; simple prime factorization 0.0
pascal pascal 5.3c, Finding Prime Factors find lowest prime factor of N; special case: N = 1 351 3.8
primalrepresentation primalrepresentation 5.3c, Finding Prime Factors factorization problem; use sieve to avoid TLE; use long long; 231-1 is a prime 258 5.4
primereduction primereduction 5.3c, Finding Prime Factors factorization problem 465 3.9
00294 Fetching from uHunt 5.3d, Prime Factors Functions numDiv(N) 0.0
10179 Fetching from uHunt 5.3d, Prime Factors Functions EulerPhi(N) 0.0
11353 Fetching from uHunt 5.3d, Prime Factors Functions numPF(N); sort variant 0.0
11728 Fetching from uHunt 5.3d, Prime Factors Functions sumDiv(N) 0.0
almostperfect almostperfect 5.3d, Prime Factors Functions sumDiv(N)-N; minor variation 1507 3.2
divisors divisors 5.3d, Prime Factors Functions return numDiv(nCk); but do not compute nCk directly; work with its prime factors 208 5.2
relatives relatives 5.3d, Prime Factors Functions EulerPhi(N); also available at UVa 10299 - Relatives 231 3.8
10699 Fetching from uHunt 5.3e, Modified Sieve numDiffPF(N) for a range 0.0
10990 Fetching from uHunt 5.3e, Modified Sieve modified sieve to compute a range of Euler Phi values; use DP to compute depth Phi values; then finally use Max 1D Range... 0.0
11426 Fetching from uHunt 5.3e, Modified Sieve pre-calculate EulerPhi(N) 0.0
12043 Fetching from uHunt 5.3e, Modified Sieve sumDiv(N) and numDiv(N); brute force 0.0
data data 5.3e, Modified Sieve numDiffPF(V) for V up to N x 1000; Brute force combination/all subsets; DP Subset 68 5.9
farey farey 5.3e, Modified Sieve pre-calculate EulerPhi(N); do prefix sum (1D RSQ) of EulerPhi(N) from 1 to each N; the answer is related to this value 257 3.6
nonprimefactors nonprimefactors 5.3e, Modified Sieve numDiv(i) - numDiffPF(i) ∀i in the range; the I/O files are large so Buffered I/O speed is needed 389 5.6
10407 Fetching from uHunt 5.3f, GCD and/or LCM subtract the set s with s[0]; find gcd 0.0
11388 Fetching from uHunt 5.3f, GCD and/or LCM understand the relationship of GCD with LCM 0.0
11417 Fetching from uHunt 5.3f, GCD and/or LCM just use brute force as input is small 0.0
jackpot jackpot 5.3f, GCD and/or LCM similar to Kattis - smallestmultiple; use Java BigInteger or other faster solutions 379 3.2
lc3411 to replace with LeetCode link soon... 5.3f, GCD and/or LCM complete search; compute product, GCD, and LCM of all subarrays 0 2.0
prsteni prsteni 5.3f, GCD and/or LCM GCD of first circle radius with subsequent circle radiuses 993 1.6
smallestmultiple smallestmultiple 5.3f, GCD and/or LCM simple LCMs of all numbers; use Java BigInteger to be safe 335 3.5
12335 Fetching from uHunt 5.3g, Factorial given the k-th permutation, recover the 1st permutation; use factorial; use Java BigInteger 0.0
12869 Fetching from uHunt 5.3g, Factorial LA 6847 - Bangkok 2014; every zero in factorial(n) is due to multiplication of factor 2 and 5; factor 2 grows faster tha... 0.0
inversefactorial inversefactorial 5.3g, Factorial good problem; number of digits in factorial 1059 5.3
loworderzeros loworderzeros 5.3g, Factorial last non zero digit of factorial; classic 288 4.2
namethatpermutation namethatpermutation 5.3g, Factorial permutation number; involving factorial 154 4.8
tutorial tutorial 5.3g, Factorial factorial is just part of the problem; pruning 1249 2.8
10680 Fetching from uHunt 5.3h, Working with PFs use primefactors([1..N]) to get LCM(1; 2; ...; N) 0.0
11347 Fetching from uHunt 5.3h, Working with PFs prime-power factorization; numDiv(N) 0.0
11395 Fetching from uHunt 5.3h, Working with PFs key hint: a square number multiplied by powers of two; i.e. 2^k * i^2 for k >= 0; i >= 1 has odd sum of divisors 0.0
consecutivesums consecutivesums 5.3h, Working with PFs work with factor; sum of Arithmetic Progression series 239 5.2
factovisors factovisors 5.3h, Working with PFs factorize m; see if it has support in n!; Legendre's formula; also available at UVa 10139 - Factovisors 373 6.4
iks iks 5.3h, Working with PFs sieve of Eratosthenes; prime factorize each number; spread the factors around to maximize final GCD/minimize total opera... 115 3.0
lc0172 to replace with LeetCode link soon... 5.3h, Working with PFs count number of prime factor 5; top-interview-150 0 4.0
lc2761 to replace with LeetCode link soon... 5.3h, Working with PFs sieve up to 1000; do prime tests 0 4.0
10174 Fetching from uHunt 5.3i, Modular Arithmetic no Spinster number 0.0
10176 Fetching from uHunt 5.3i, Modular Arithmetic convert binary to decimal digit by digit; do modulo 131071 to the intermediate result 0.0
10212 Fetching from uHunt 5.3i, Modular Arithmetic multiply numbers from N down to N-M+1; use / 10 to discard the trailing zero(es); use % 1 Billion 0.0
10489 Fetching from uHunt 5.3i, Modular Arithmetic keep values small with modulo 0.0
anothercandies anothercandies 5.3i, Modular Arithmetic simple modular arithmetic 1843 2.7
ones ones 5.3i, Modular Arithmetic no factor of 2 and 5 implies that there is no trailing zero; also available at UVa 10127 - Ones 567 4.6
threedigits threedigits 5.3i, Modular Arithmetic simulate factorial computation; remove trailing zeroes; keep many last few non-zero digits using modulo 289 5.9
10090 Fetching from uHunt 5.3j, Extended Euclid use solution for Linear Diophantine Equation 0.0
10104 Fetching from uHunt 5.3j, Extended Euclid pure Ext Euclid problem 0.0
10633 Fetching from uHunt 5.3j, Extended Euclid let C = N-M, N = 10a+b, and M = a; Linear Diophantine Equation: 9a+b = C 0.0
10673 Fetching from uHunt 5.3j, Extended Euclid uses Extended Euclidean 0.0
candydistribution candydistribution 5.3j, Extended Euclid the problem boils down to finding C-1 (mod K); be careful when the answer is "IMPOSSIBLE" or ≤ K 199 4.9
modulararithmetic modulararithmetic 5.3j, Extended Euclid the division operation requires modular inverse; use Extended Euclidean algorithm 333 2.9
soyoulikeyourfoodhot soyoulikeyourfoodhot 5.3j, Extended Euclid Linear Diophantine Equation; still solvable with brute force 103 5.2
10922 Fetching from uHunt 5.3k, Divisibility Test test divisibility by 9 0.0
10929 Fetching from uHunt 5.3k, Divisibility Test test divisibility by 11 0.0
11344 Fetching from uHunt 5.3k, Divisibility Test use divisibility theory of [1..12] 0.0
divisible divisible 5.3k, Divisibility Test divisibility; linear pass algorithm 327 4.3
lc1952 to replace with LeetCode link soon... 5.3k, Divisibility Test divisibility test up to sqrt of n 0 2.0
meowfactor meowfactor 5.3k, Divisibility Test divisibility test of 9^ans; small range of ans 310 3.5
thinkingofanumber thinkingofanumber 5.3k, Divisibility Test simple range; use min/max properly; then small divisibility tests 379 3.8
00763 Fetching from uHunt 5.4a, Fibonacci Numbers Zeckendorf representation; greedy; Big Integer 0.0
10689 Fetching from uHunt 5.4a, Fibonacci Numbers easy; Pisano period 0.0
anti11 anti11 5.4a, Fibonacci Numbers this problem degenerates into a modified Fibonacci numbers 518 2.7
batmanacci batmanacci 5.4a, Fibonacci Numbers Fibonacci; observation on N; Divide and Conquer 331 3.8
lc0070 to replace with LeetCode link soon... 5.4a, Fibonacci Numbers basically compute Fib(n+1); DP; top-100-liked; top-interview-150 0 2.0
lc1137 to replace with LeetCode link soon... 5.4a, Fibonacci Numbers basic Tribonacci; DP; leetcode-75 0 2.0
rijeci rijeci 5.4a, Fibonacci Numbers simple simulation with a single loop; Fibonacci 2478 1.5
00369 Fetching from uHunt 5.4b, Binomial Coefficients be careful with overflow issue 0.0
10541 Fetching from uHunt 5.4b, Binomial Coefficients a good combinatorics problem 0.0
11955 Fetching from uHunt 5.4b, Binomial Coefficients pure application; DP 0.0
12712 Fetching from uHunt 5.4b, Binomial Coefficients the answer is sum i=M to N of C(L*L;i)*i!; but simplify the computation of this formula instead of running it directly 0.0
election election 5.4b, Binomial Coefficients compute the answers with help of binomial coefficients 213 6.2
lc0118 to replace with LeetCode link soon... 5.4b, Binomial Coefficients basic bottom-up DP to generate Pascal's triangle; top-100-liked 0 2.0
lockedtreasure lockedtreasure 5.4b, Binomial Coefficients the answer is nCm-1 321 2.8
oddbinom oddbinom 5.4b, Binomial Coefficients OEIS A006046 245 3.5
10007 Fetching from uHunt 5.4c, Catalan Numbers answer is Cat(n) * n!; BigInteger 0.0
10223 Fetching from uHunt 5.4c, Catalan Numbers you can precalculate the answers as there are only 19 Catalan Numbers < 2^{32}-1 0.0
10312 Fetching from uHunt 5.4c, Catalan Numbers number of binary bracketing = Cat(n); number of bracketing = Super-Catalan numbers 0.0
catalan catalan 5.4c, Catalan Numbers basic Catalan Numbers 521 3.6
catalansquare catalansquare 5.4c, Catalan Numbers Catalan Numbers++; follow the description 507 3.5
fiat fiat 5.4c, Catalan Numbers N-th Catalan Number; use Fermat's little theorem 75 6.7
lc0096 to replace with LeetCode link soon... 5.4c, Catalan Numbers Catalan numbers; pre-calculateable 1 to 19 0 4.0
11310 Fetching from uHunt 5.4d, Others, Easier requires DP: let dp[i] be the number of ways the cakes can be packed for a box 2*i 0.0
11401 Fetching from uHunt 5.4d, Others, Easier spot the pattern 0.0
11597 Fetching from uHunt 5.4d, Others, Easier uses knowledge of graph theory; the answer is very trivial 0.0
12463 Fetching from uHunt 5.4d, Others, Easier double the socks and the shoes to simplify the problem 0.0
character character 5.4d, Others, Easier OEIS A000295 841 2.4
honey honey 5.4d, Others, Easier OEIS A002898 415 2.4
integerdivision integerdivision 5.4d, Others, Easier count frequencies of each remainder of [0..d-1]; add C(freq, 2) per such remainder 242 3.3
lc1175 to replace with LeetCode link soon... 5.4d, Others, Easier let k be number of primes up to n; output k! * (n-k)!, mod 10^9+7 0 2.0
01224 Fetching from uHunt 5.4e, Others, Harder LA 3904 - Seoul07; derive formula from observing the small instances first 0.0
10784 Fetching from uHunt 5.4e, Others, Harder the number of diagonals in n-gon = n*(n-3)/2; use it to derive the solution 0.0
11069 Fetching from uHunt 5.4e, Others, Harder use Dynamic Programming 0.0
11538 Fetching from uHunt 5.4e, Others, Harder count along rows; columns; and diagonals 0.0
anagramcounting anagramcounting 5.4e, Others, Harder use Big Integer 1117 3.1
incognito incognito 5.4e, Others, Harder count frequencies; combinatorics; minus one 791 2.7
tritiling tritiling 5.4e, Others, Harder there are two related recurrences here; also available at UVa 10918 - Tri Tiling 465 2.1
01636 Fetching from uHunt 5.5a, Probability, Easier LA 4596 - NorthEasternEurope09; ad hoc probability question, one tricky special case involving all zeroes 0.0
10238 Fetching from uHunt 5.5a, Probability, Easier DP; s: (dice_left, score); try F values; Big Integer; no need to simplify the fraction; see UVa 10759 0.0
10491 Fetching from uHunt 5.5a, Probability, Easier two ways to get a car: either pick a cow first; then switch to a car; or pick a car first; and then switch to another ca... 0.0
11181 Fetching from uHunt 5.5a, Probability, Easier iterative brute force; try all possibilities 0.0
bobby bobby 5.5a, Probability, Easier computation of expected value 618 2.8
dicebetting dicebetting 5.5a, Probability, Easier s: (dice_left, distinct_numbers_so_far); each throw can increase distinct_numbers_so_far or not 261 3.3
odds odds 5.5a, Probability, Easier complete search; simple probability 142 2.5
10056 Fetching from uHunt 5.5b, Probability, Harder get the closed form formula 0.0
10648 Fetching from uHunt 5.5b, Probability, Harder DP; s: (rem_boxes; num_empty) 0.0
11176 Fetching from uHunt 5.5b, Probability, Harder DP, s: (rem_games, streak); t: lose this game, or win the next W = [1..n] games and lose the (W+1)-th game 0.0
11628 Fetching from uHunt 5.5b, Probability, Harder p[i] = ticket bought by i at the last round/total tickets bought at the last round by all n; gcd 0.0
anthony anthony 5.5b, Probability, Harder DP probability; need to drop one parameter (N or M) and recover it from the other one 203 5.2
goodcoalition goodcoalition 5.5b, Probability, Harder DP probability; like KNAPSACK 276 3.4
lostinthewoods lostinthewoods 5.5b, Probability, Harder simulate random walks of various lengths and distribute the probabilities per iteration; the answer will converge eventu... 77 3.1
00350 Fetching from uHunt 5.6a, Cycle Finding very basic cycle-finding problem; simply run Floyd's cycle-finding algorithm 0.0
11036 Fetching from uHunt 5.6a, Cycle Finding cycle-finding; evaluate Reverse Polish f with a stack 0.0
11053 Fetching from uHunt 5.6a, Cycle Finding cycle-finding; the answer is N-lambda 0.0
fibonaccicycles fibonaccicycles 5.6a, Cycle Finding detect cycle of fib(n)%k using fast data structure 118 3.2
lc0287 to replace with LeetCode link soon... 5.6a, Cycle Finding find μ, start of the cycle; Floyd's cycle-finding algorithm; popularized by Joma Tech YouTube video; top-100-liked 0 4.0
rats rats 5.6a, Cycle Finding string processing plus cycle-finding; unordered_set 92 6.3
10111 Fetching from uHunt 5.7a, Game Theory (Basic) Tic-Tac-Toe; minimax; backtracking 0.0
10536 Fetching from uHunt 5.7a, Game Theory (Basic) model the 4*4 board and 48 possible pins as bitmask; then this is a simple two player game 0.0
bachetsgame bachetsgame 5.7a, Game Theory (Basic) 2 players game; Dynamic Programming; also available at UVa 10404 - Bachet's Game 724 2.1
blockgame2 blockgame2 5.7a, Game Theory (Basic) observe the pattern; 2 winnable cases if N == M and N%M == 0; only 1 move if M < N < 2M; we can always win if N &g... 314 3.2
euclidsgame euclidsgame 5.7a, Game Theory (Basic) minimax; backtracking; also available at UVa 10368 - Euclid's Game 199 4.8
lc3360 to replace with LeetCode link soon... 5.7a, Game Theory (Basic) simulate the process to determine the winner 0 2.0
linije linije 5.7a, Game Theory (Basic) game theory; check conditions on how Mirko can win and when Slavko can win; involves MCBM 39 7.9
10229 Fetching from uHunt 5.8a, Matrix Power Fibonacci; modPow 0.0
10655 Fetching from uHunt 5.8a, Matrix Power derive the square matrix 0.0
12796 Fetching from uHunt 5.8a, Matrix Power count the number of paths of length L in an undirected graph where L can be up to 2^30 0.0
checkingforcorrectness checkingforcorrectness 5.8a, Matrix Power Java Big Integer; one subtask uses modPow 244 4.1
lc0050 to replace with LeetCode link soon... 5.8a, Matrix Power D&C exponentiation; programming-skills; top-interview-150 0 4.0
porpoises porpoises 5.8a, Matrix Power Fibonacci; matrix power; modulo 268 2.9
squawk squawk 5.8a, Matrix Power count the number of paths of length L in an undirected graph after t steps that are reachable from source s 409 3.5
00213 Fetching from uHunt 6.2a, Cipher, Harder LA 5152 - WorldFinals SanAntonio91 0.0
00554 Fetching from uHunt 6.2a, Cipher, Harder try all shifts; output formatting 0.0
11385 Fetching from uHunt 6.2a, Cipher, Harder string manipulation and Fibonacci 0.0
crackingthecode crackingthecode 6.2a, Cipher, Harder one corner case involving the 25th to 26th character determination 48 6.4
itsasecret itsasecret 6.2a, Cipher, Harder playfair cipher; 2D array; quite tedious 81 5.9
playfair playfair 6.2a, Cipher, Harder follow the description; a bit tedious; also available at UVa 11697 - Playfair Cipher 156 2.5
progressivescramble progressivescramble 6.2a, Cipher, Harder the encode part is trivial; the decode part requires a bit of thinking 977 2.1
textencryption textencryption 6.2a, Cipher, Harder convert input alphabets to UPPERCASEs; loop 305 3.2
10854 Fetching from uHunt 6.2b, Input Parsing (Rec) recursive parsing plus counting 0.0
11070 Fetching from uHunt 6.2b, Input Parsing (Rec) recursive grammar evaluation 0.0
11291 Fetching from uHunt 6.2b, Input Parsing (Rec) recursive grammar check 0.0
calculator calculator 6.2b, Input Parsing (Rec) recursive parser and evaluator 351 3.3
otpor otpor 6.2b, Input Parsing (Rec) parallel vs series evaluation; write a recursive parser; or use linear pass with stack 94 4.3
polish polish 6.2b, Input Parsing (Rec) recursive parser 224 3.3
subexpression subexpression 6.2b, Input Parsing (Rec) recursive parsing; use DP; similar to https://visualgo.net/en/recursion tree versus DAG 44 5.9
00325 Fetching from uHunt 6.2c, Regular Expression trivial with regex 0.0
00494 Fetching from uHunt 6.2c, Regular Expression trivial with regex 0.0
00576 Fetching from uHunt 6.2c, Regular Expression solvable with regex 0.0
10058 Fetching from uHunt 6.2c, Regular Expression solvable with regex 0.0
apaxiaaans apaxiaaans 6.2c, Regular Expression solvable with regex 6751 1.4
hidden hidden 6.2c, Regular Expression just a careful 1D array manipulation; we can also use regex 1100 2.3
lindenmayorsystem lindenmayorsystem 6.2c, Regular Expression DAT; map char to string; simulation; max answer ≤ 30*5^5; we can also use regex 302 2.5
00918 Fetching from uHunt 6.2d, Output Formatting, H tedious; follow the steps 0.0
11403 Fetching from uHunt 6.2d, Output Formatting, H similar with UVa 00338; tedious 0.0
12155 Fetching from uHunt 6.2d, Output Formatting, H LA 4403 - KualaLumpur08; use proper index manipulation 0.0
asciifigurerotation asciifigurerotation 6.2d, Output Formatting, H rotate the input 90 degrees clockwise; remove trailing whitespaces; tedious 521 3.5
imagedecoding imagedecoding 6.2d, Output Formatting, H simple Run-Length Encoding 321 3.4
juryjeopardy juryjeopardy 6.2d, Output Formatting, H tedious problem 309 2.3
nizovi nizovi 6.2d, Output Formatting, H formatting with indentation; not that trivial but sample input/output helps 199 3.8
00644 Fetching from uHunt 6.2e, String Comparison use brute force 0.0
11048 Fetching from uHunt 6.2e, String Comparison flexible string comparison with respect to a dictionary 0.0
11056 Fetching from uHunt 6.2e, String Comparison sorting; case-insensitive string comparison 0.0
11734 Fetching from uHunt 6.2e, String Comparison custom comparison 0.0
lc0014 to replace with LeetCode link soon... 6.2e, String Comparison complete search; try each prefix; see if it all strings start with it; top-interview-150 0 2.0
phonelist phonelist 6.2e, String Comparison sort the numbers; see if num i is a prefix of num i+1 1955 4.3
rhyming rhyming 6.2e, String Comparison compare suffix of a common word with the list of other given words 296 2.5
smartphone smartphone 6.2e, String Comparison compare prefix so far with the target string and the 3 suggestions; output 1 of 4 options with shortest number of keypre... 354 2.6
11483 Fetching from uHunt 6.2f, Really Ad Hoc straightforward; use 'escape character' 0.0
12916 Fetching from uHunt 6.2f, Really Ad Hoc factorize n; string period; also see UVa 11452 0.0
irepeatmyself irepeatmyself 6.2f, Really Ad Hoc string period; complete search 380 2.4
lc0459 to replace with LeetCode link soon... 6.2f, Really Ad Hoc complete search; test repeated substring; programming-skills 0 2.0
lc0890 to replace with LeetCode link soon... 6.2f, Really Ad Hoc custom matching; map each word to appropriate index (signature); compare signatures 0 4.0
periodicstrings periodicstrings 6.2f, Really Ad Hoc brute force; skip non divisor 299 3.0
raggedright raggedright 6.2f, Really Ad Hoc just simulate the requirement 1708 1.8
zipfslaw zipfslaw 6.2f, Really Ad Hoc sort the words to simplify this problem; also available at UVa 10126 - Zipf's Law 157 5.7
01192 Fetching from uHunt 6.3a, DP String, Classic LA2460 - Singapore01; classic String Alignment DP problem with a bit of (unclear) output formatting 0.0
12747 Fetching from uHunt 6.3a, DP String, Classic similar to UVa 10635 0.0
13146 Fetching from uHunt 6.3a, DP String, Classic classic Edit Distance problem 0.0
inflagrantedelicto inflagrantedelicto 6.3a, DP String, Classic k_p is always 2 (read the problem description); k_r is the LCS of the two permutations plus one; O(n log k) solution 75 4.8
lc1143 to replace with LeetCode link soon... 6.3a, DP String, Classic classic; DP; leetcode-75; top-100-liked 0 4.0
pandachess pandachess 6.3a, DP String, Classic LCS of 2 permutations → LIS; O(n log k) solution; also see UVa 10635 267 6.0
princeandprincess princeandprincess 6.3a, DP String, Classic find LCS of two permutations; also available at UVa 10635 - Prince and Princess 140 6.7
11258 Fetching from uHunt 6.3b, DP String, Non Classic dp(i) = int from substring [i..k] dp(k) 0.0
11552 Fetching from uHunt 6.3b, DP String, Non Classic dp(i; c) = minimum number of chunks after considering the first i segments ending with character c 0.0
exam exam 6.3b, DP String, Non Classic s: (pos, correct_left); t: either your friend is wrong or your friend is right, process accordingly; easier solution exi... 891 1.9
heritage heritage 6.3b, DP String, Non Classic s: (cur_pos); t: try all N words in dictionary; final answer modulo prime 348 5.2
hillnumbers hillnumbers 6.3b, DP String, Non Classic digit DP; s: (prev_digit, pos, is_rising, is_lower); try digit by digit 84 6.7
lc0097 to replace with LeetCode link soon... 6.3b, DP String, Non Classic s: (i, j); k is derived from i+j; t: use a[i] or b[i] next; top-interview-150 0 4.0
stringfactoring stringfactoring 6.3b, DP String, Non Classic s: the min weight of substring [i..j]; also available at UVa 11022 - String Factoring 57 5.1
01449 Fetching from uHunt 6.4a, String Matching LA 4670 - Hefei09; just use strstr; Suffix Array will get TLE as there are too many long strings to be processed 0.0
11837 Fetching from uHunt 6.4a, String Matching transform the input of X notes into X-1 distances; then apply KMP 0.0
geneticsearch geneticsearch 6.4a, String Matching multiple string matchings 346 2.1
lc0028 to replace with LeetCode link soon... 6.4a, String Matching simple string matching; programming-skills; top-interview-150 0 2.0
powerstrings powerstrings 6.4a, String Matching find s in s+s; similar with UVa 00455; also available at UVa 10298 - Power Strings 451 5.2
quiteaproblem quiteaproblem 6.4a, String Matching trivial string matching per line 1212 2.1
scrollingsign scrollingsign 6.4a, String Matching modified string matching; complete search; also available at UVa 11576 - Scrolling Sign 238 3.1
00736 Fetching from uHunt 6.4b, String Matching, 2D 2D grid; a bit modified 0.0
10010 Fetching from uHunt 6.4b, String Matching, 2D 2D grid; backtracking 0.0
11283 Fetching from uHunt 6.4b, String Matching, 2D 2D grid; backtracking; do not count twice 0.0
boggle boggle 6.4b, String Matching, 2D 2D grid; backtracking 323 3.8
kinarow kinarow 6.4b, String Matching, 2D brute the top left point of each possible x or o row, then straight-line (horizontal, vertical) or two diagonals 2D stri... 107 4.6
knightsearch knightsearch 6.4b, String Matching, 2D 2D grid; backtracking or DP 425 3.2
lc0079 to replace with LeetCode link soon... 6.4b, String Matching, 2D 2D grid; backtracking; top-100-liked; top-interview-150 0 4.0
bing bing 6.5a, Trie map all prefixes to frequencies using Hash Table; or use Trie 1061 3.6
lc0208 to replace with LeetCode link soon... 6.5a, Trie Trie implementation; leetcode-75; top-100-liked; top-interview-150 0 4.0
lc0648 to replace with LeetCode link soon... 6.5a, Trie use Trie to speed-up the identification of the shortest root for each derivative 0 4.0
lc1268 to replace with LeetCode link soon... 6.5a, Trie use Trie to speed-up the search process; leetcode-75 0 4.0
lc2416 to replace with LeetCode link soon... 6.5a, Trie we can use Trie or frequency Counter of each prefixes 0 6.0
01254 Fetching from uHunt 6.5b, Suffix Tree/Array LA 4657 - Jakarta09; Suffix Array with Segment Tree or Sparse Table; LCP range 0.0
01584 Fetching from uHunt 6.5b, Suffix Tree/Array LA 3225 - Seoul04; min lexicographic rotation; similar with UVa 00719; other solutions exist 0.0
automatictrading automatictrading 6.5b, Suffix Tree/Array Suffix Array; LCP of a range; use Sparse Table 160 5.2
buzzwords buzzwords 6.5b, Suffix Tree/Array Longest Repeated Substring that appears X times (2 ≤ X < N); also available at UVa 11855 - Buzzwords 141 5.0
lc1044 to replace with LeetCode link soon... 6.5b, Suffix Tree/Array classic Longest Repeated Substring problem; solvable with Suffix Array 0 6.0
suffixarrayreconstruction suffixarrayreconstruction 6.5b, Suffix Tree/Array clever creative problem involving Suffix Array concept; be careful that '*' can be more than one character 125 4.1
suffixsorting suffixsorting 6.5b, Suffix Tree/Array basic Suffix Array construction problem; be careful with terminating symbol 201 5.7
12467 Fetching from uHunt 6.6a, String Hashing hashing/'border' of KMP; see UVa 11475 0.0
12604 Fetching from uHunt 6.6a, String Hashing try Rabin-Karp/KMP up to 62 times 0.0
hashing hashing 6.6a, String Hashing the problem description is very clear; good rolling hash practice; or use Suffix Array+Sparse Table 142 7.3
lc0187 to replace with LeetCode link soon... 6.6a, String Hashing classic rolling hash task; maintain hash of 10-characters substring as the window slides 0 4.0
stringmatching stringmatching 6.6a, String Hashing try Rabin-Karp or KMP 719 4.5
00156 Fetching from uHunt 6.7a, Anagram easier with algorithm::sort 0.0
00195 Fetching from uHunt 6.7a, Anagram use algorithm::next_permutation 0.0
12641 Fetching from uHunt 6.7a, Anagram anagram problem variation 0.0
12770 Fetching from uHunt 6.7a, Anagram count frequencies; print odd frequency characters with except the last one -- put it in the middle of a palindrome 0.0
lc0242 to replace with LeetCode link soon... 6.7a, Anagram sort s and t; compare; programming-skills; top-interview-150 0 2.0
multigram multigram 6.7a, Anagram brute force lengths that is divisor of the original length of the string; test 221 2.8
00401 Fetching from uHunt 6.7b, Palindrome (Checking) simple palindrome check 0.0
10848 Fetching from uHunt 6.7b, Palindrome (Checking) related to UVa 10453; palindrome check, character frequency check, and a few others 0.0
11888 Fetching from uHunt 6.7b, Palindrome (Checking) let ss = s+s; find reverse(s) in ss, but it cannot match the first n chars or the last n chars of ss 0.0
kaleidoscopicpalindromes kaleidoscopicpalindromes 6.7b, Palindrome (Checking) test all; when you try enlarging k, the answers are actually 'small' 233 3.2
lc0647 to replace with LeetCode link soon... 6.7b, Palindrome (Checking) complete search all substrings plus DP isPalindrome(l, r) speedup 0 4.0
palindromesubstring palindromesubstring 6.7b, Palindrome (Checking) try all pairs of O(n^2) substrings with at least 2 characters; keep the ones that are palindrome (use DP) in a sorted se... 298 4.2
peragrams peragrams 6.7b, Palindrome (Checking) only one odd frequency character can be in the center of palindrome once; the rest need to have even frequency 1692 1.7
01239 Fetching from uHunt 6.7c, Palindrome (Generating) LA 4144 - Jakarta08; as S <= 1000; brute-force is enough; consider odd and even length palindromes 0.0
10018 Fetching from uHunt 6.7c, Palindrome (Generating) generating palindrome with specific math simulation; very easy 0.0
12718 Fetching from uHunt 6.7c, Palindrome (Generating) LA 6659 - Dhaka13; try all substrings; count character frequencies in them and analyze 0.0
evilstraw evilstraw 6.7c, Palindrome (Generating) greedily match leftmost char s[0]/rightmost char s[n-1] with rightmost/leftmost matching s[i], respectively 137 3.8
lc0409 to replace with LeetCode link soon... 6.7c, Palindrome (Generating) count character frequencies; even cases are easy; odd cases need a small observation 0 2.0
names names 6.7c, Palindrome (Generating) add a letter or change a letter; complete search 368 4.0
01595 Fetching from uHunt 7.2a, Points use set to record the positions of all sorted points; check half of the points if the symmetries are in the set too? 0.0
11894 Fetching from uHunt 7.2a, Points about rotating and translating points 0.0
browniepoints browniepoints 7.2a, Points points and quadrants; simple; also available at UVa 10865 - Brownie Points 154 2.3
cursethedarkness cursethedarkness 7.2a, Points Euclidean dist 596 2.2
imperfectgps imperfectgps 7.2a, Points Euclidean dist; simulation 487 4.2
jointjogjam jointjogjam 7.2a, Points take the max Euclidean dist between two starting vs two ending points 448 1.6
lc1232 to replace with LeetCode link soon... 7.2a, Points check if all other points are collinear with the line defined by the first two points; programming-skills 0 2.0
10263 Fetching from uHunt 7.2b, Lines use distToLineSegment 0.0
11783 Fetching from uHunt 7.2b, Lines O(N^2) brute force line segment intersection tests 0.0
13117 Fetching from uHunt 7.2b, Lines dist + distToLineSegment 0.0
hurricanedanger hurricanedanger 7.2b, Lines distance from point to line (not vector); be careful of precision error; work with integers 114 5.9
logo2 logo2 7.2b, Lines n vectors that sum to 0; given n-1 vectors, find the unknown vector; also available at UVa 11519 - Logo 2 114 5.6
platforme platforme 7.2b, Lines line segment intersection tests; N ≤ 100; complete search 210 2.7
unlockpattern unlockpattern 7.2b, Lines complete search; Euclidean dist 902 1.7
01388 Fetching from uHunt 7.2c, Circles LA 3708 - NortheasternEurope06; divide the circle into n sectors first and then into (n m) sectors 0.0
10678 Fetching from uHunt 7.2c, Circles area of an ellipse; generalization of the formula for area of a circle 0.0
amsterdamdistance amsterdamdistance 7.2c, Circles arcs of circles; no need to model this as an SSSP problem/Dijkstra's 571 2.9
biggest biggest 7.2c, Circles find biggest area of sector using simulation; use array (not that larget) to avoid precision error 147 6.6
estimatingtheareaofacircle estimatingtheareaofacircle 7.2c, Circles PI estimation experiment 2084 1.6
lc1828 to replace with LeetCode link soon... 7.2c, Circles for each circle query, check how many points are inside; O(QN) 0 4.0
ornaments ornaments 7.2c, Circles arch length plus two times tangent lengths 236 2.2
00427 Fetching from uHunt 7.2d, Triangles (Trig) for each 2 consecutive corridors, try rotating the piano by a angle α ∈ [0.1..89.9] degrees; trigonometry 0.0
11326 Fetching from uHunt 7.2d, Triangles (Trig) trigonometry; tangent; reflection trick 0.0
alldifferentdirections alldifferentdirections 7.2d, Triangles (Trig) use trigonometry to compute x and y displacement 446 2.6
billiard billiard 7.2d, Triangles (Trig) enlarge the billiard table; then this is solvable with atan2 856 1.6
egypt egypt 7.2d, Triangles (Trig) Pythagorean theorem/triple; also available at UVa 11854 - Egypt 862 1.9
lc1925 to replace with LeetCode link soon... 7.2d, Triangles (Trig) Pythagorean triples; complete search 0 2.0
mountainbiking mountainbiking 7.2d, Triangles (Trig) up to 4 line segments; simple trigonometry; simple Physics/Kinematic equation 216 2.8
00438 Fetching from uHunt 7.2e, Triangles + Circles compute triangle's circumcircle 0.0
10577 Fetching from uHunt 7.2e, Triangles + Circles get center radius of outer circle from 3 points; get all vertices; get the min-x/max-x/min-y/max-y of the polygon; also ... 0.0
11281 Fetching from uHunt 7.2e, Triangles + Circles circumcircle for a non obtuse triangle; largest side of the triangle for an obtuse triangle 0.0
13215 Fetching from uHunt 7.2e, Triangles + Circles area of rectangle minus area of squares and equilateral triangles 0.0
cropeasy cropeasy 7.2e, Triangles + Circles complete search 3 points/tree; check if the center is integer 178 3.0
stickysituation stickysituation 7.2e, Triangles + Circles see if 3 sides form a triangle; see UVa 11579 675 2.7
trilemma trilemma 7.2e, Triangles + Circles triangle properties; sort the 3 sides first 225 3.6
00209 Fetching from uHunt 7.2f, Quadrilaterals LA 5148 - WorldFinals SanAntonio91; brute force check; answer is either triangle, parallelogram, or hexagon 0.0
11800 Fetching from uHunt 7.2f, Quadrilaterals use next_permutation to try all possible 4! = 24 permutations of 4 points; check the requirements 0.0
cetvrta cetvrta 7.2f, Quadrilaterals sort the x and y points, then you will know the 4th point 4727 1.3
lc0836 to replace with LeetCode link soon... 7.2f, Quadrilaterals set rec2 as reference point; simple case analysis of where rec1 is vs rec2 0 2.0
officespace officespace 7.2f, Quadrilaterals rectangles; small numbers; 2D Boolean arrays 143 5.5
rectanglesurrounding rectanglesurrounding 7.2f, Quadrilaterals rectangles; small; 2D Boolean arrays 187 3.8
roundedbuttons roundedbuttons 7.2f, Quadrilaterals in-rectangle/in-square test; in-4-circles tests 176 2.9
00634 Fetching from uHunt 7.3a, Polygon, Easier basic inPolygon routine; notice that the input polygon can be convex or concave 0.0
11447 Fetching from uHunt 7.3a, Polygon, Easier area of polygon 0.0
convexhull convexhull 7.3a, Polygon, Easier basic convex hull problem; be careful with duplicate points and collinear points 644 4.8
cuttingcorners cuttingcorners 7.3a, Polygon, Easier simulation of angle checks 95 3.5
lc0587 to replace with LeetCode link soon... 7.3a, Polygon, Easier Convex Hull; collinear allowed 0 6.0
robotprotection robotprotection 7.3a, Polygon, Easier simply find the area of convex hull 236 2.4
00361 Fetching from uHunt 7.3b, Polygon, Harder check if a point is inside CH of Cop/Robber; if $pt$ is inside CH, pt satisfies the requirement 0.0
01111 Fetching from uHunt 7.3b, Polygon, Harder LA 5138 - WorldFinals Orlando11; CH; output minimax distance of each CH side to the other vertices 0.0
10256 Fetching from uHunt 7.3b, Polygon, Harder given 2 CHs, output 'No' if there is a point in 1st CH inside the 2nd one; 'Yes' otherwise 0.0
11265 Fetching from uHunt 7.3b, Polygon, Harder seems to be a complex problem; but essentially just cutPolygon; inPolygon; area 0.0
convex convex 7.3b, Polygon, Harder must understand the concept of convex polygon; a bit of mathematical insights: GCD; sort 132 6.4
pointinpolygon pointinpolygon 7.3b, Polygon, Harder in/out and on polygon 311 5.5
roberthood roberthood 7.3b, Polygon, Harder the classic furthest pair problem; use convex hull and then rotating caliper 376 4.6
00535 Fetching from uHunt 7.4a, 3D Geometry gcDistance 0.0
00737 Fetching from uHunt 7.4a, 3D Geometry cube and cube intersection 0.0
00815 Fetching from uHunt 7.4a, 3D Geometry LA 5215 - WorldFinals Eindhoven99; volume; greedy 0.0
11817 Fetching from uHunt 7.4a, 3D Geometry gcDistance; 3D Euclidean distance; also available at Kattis - tunnelingtheearth 0.0
airlinehub airlinehub 7.4a, 3D Geometry gcDistance; also available at UVa 10316 - Airline Hub 211 6.6
beavergnaw beavergnaw 7.4a, 3D Geometry volumes of cylinders and cones; inclusion-exclusion; also available at UVa 10297 - Beavergnaw 1210 1.4
bottles bottles 7.4a, 3D Geometry LA 6027 - WorldFinals Warsaw12; BSTA+geometric formula; also available at UVa 01280 - Curvy Little Bottles 217 3.0
flowers flowers 7.4a, 3D Geometry the key part of this problem is integration 63 4.4
movingday movingday 7.4a, 3D Geometry output volume of the largest cuboid - V 261 2.1
00711 Fetching from uHunt 8.2a, Harder Backtracking backtracking with pruning 0.0
01052 Fetching from uHunt 8.2a, Harder Backtracking LA 3565 - WorldFinals SanAntonio06; backtracking with some form of bitmask 0.0
11090 Fetching from uHunt 8.2a, Harder Backtracking this is the simplest form of Min Mean Cycle problem; however it has small constraints and thus this problem is still sol... 0.0
11451 Fetching from uHunt 8.2a, Harder Backtracking the input constraints are small; backtracking with bitmask without memoization; or use DP 0.0
11699 Fetching from uHunt 8.2a, Harder Backtracking try all the possible row combinations on which we put rooks and keep the best 0.0
committeeassignment committeeassignment 8.2a, Harder Backtracking backtracking; pruning; add a member to existing committee or create a new committee; TLE with DP bitmask 68 7.4
greatswercporto greatswercporto 8.2a, Harder Backtracking use backtracking with pruning; testing up to 10! possible permutations possibly TLE 120 4.1
holeynqueensbatman holeynqueensbatman 8.2a, Harder Backtracking similar with UVa 11195 527 2.2
01600 Fetching from uHunt 8.2b, State-Space, BFS, E LA 3670 - Hanoi06; s: (row; col; k_left); reset k_left to the original k as soon as the robot enters a non obstacle cell 0.0
10047 Fetching from uHunt 8.2b, State-Space, BFS, E s: (row, col, dir, color) 0.0
12135 Fetching from uHunt 8.2b, State-Space, BFS, E LA 4201 - Dhaka08; s: (bitmask); BFS; similar with UVa 11974 0.0
ecoins ecoins 8.2b, State-Space, BFS, E s: (conventional-value, infotechnological-value); BFS; also available at UVa 10306 - e-Coins 169 4.6
flipfive flipfive 8.2b, State-Space, BFS, E s: (bitmask); only 2^9 = 512 grid configurations; BFS 621 2.7
lc0433 to replace with LeetCode link soon... 8.2b, State-Space, BFS, E unweighted SSSP; BFS; s: (8-char-gene); t: as described; top-interview-150 0 4.0
safe safe 8.2b, State-Space, BFS, E s: (convert 3x3 grid into a base 4 integer); BFS 181 3.0
11198 Fetching from uHunt 8.2c, State-Space, BFS, H s: (permutation); tricky to code 0.0
11212 Fetching from uHunt 8.2c, State-Space, BFS, H meet in the middle 0.0
11329 Fetching from uHunt 8.2c, State-Space, BFS, H s: (bitmask); 4 bits for die position; 16 bits for cells with fleas; 6 bits for side with a flea; use map; tedious 0.0
keyboard keyboard 8.2c, State-Space, BFS, H LA 7155 - WorldFinals Marrakech15; s: (row, col, char_typed); also available at UVa 01714 - Keyboarding 258 5.0
lc0126 to replace with LeetCode link soon... 8.2c, State-Space, BFS, H map string to indices; BFS on state-space graph; backtrack 0 6.0
robotmaze robotmaze 8.2c, State-Space, BFS, H s: (r, c, dir, steps); be careful of corner cases 87 5.7
robotturtles robotturtles 8.2c, State-Space, BFS, H s: (r, c, dir, bitmask_ice_castles); print solution; very tedious 114 4.5
00658 Fetching from uHunt 8.2d, State-Space, Dijkstra s: (bitmask---whether a bug is present or not); the state-space graph is weighted 0.0
01048 Fetching from uHunt 8.2d, State-Space, Dijkstra LA 3561 - WorldFinals SanAntonio06; tedious state-space search problem; use Dijkstra's 0.0
01057 Fetching from uHunt 8.2d, State-Space, Dijkstra LA 3570 - WorldFinals SanAntonio06; Floyd-Warshall; APSP; reduce to weighted SSSP problem; Dijkstra's 0.0
10269 Fetching from uHunt 8.2d, State-Space, Dijkstra use Floyd-Warshall to pre-compute APSP using only Villages; use Dijkstra's on s: (u, super_run_left) 0.0
bumped bumped 8.2d, State-Space, Dijkstra s: (city, has_use_free_ticket); use Dijkstra's 545 4.4
destinationunknown destinationunknown 8.2d, State-Space, Dijkstra use Dijkstra's twice; one normally; one with s: (point, has_edge_g_h_used); compare the results 101 5.6
justpassingthrough justpassingthrough 8.2d, State-Space, Dijkstra s: (r, c, n_left); Dijkstra's/SSSP on DAG 92 5.1
01172 Fetching from uHunt 8.3a, DP level 3 LA 3986 - SouthWesternEurope07; weighted bipartite matching with additional constraints 0.0
01211 Fetching from uHunt 8.3a, DP level 3 LA 3404 - Tokyo05; precompute T[L], the time to run a path of length L; s: (i) - checkpoint i is we change tire 0.0
10645 Fetching from uHunt 8.3a, DP level 3 s: (days_left, budget_left, prev_dish, prev_dish_cnt); the first 2 params are knapsack-style; the last 2 params to deter... 0.0
aspenavenue aspenavenue 8.3a, DP level 3 sort; compute tree positions; s: (l_left, r_left), t: put next tree on the left/right; also available at UVa 11555 - Asp... 223 5.8
busticket busticket 8.3a, DP level 3 s: (day_i); t: either buy daily ticket or jump to end of period ticket (use binary search to avoid TLE) 186 4.4
lc0188 to replace with LeetCode link soon... 8.3a, DP level 3 s: (i, own, k_left); t: skip or buy/sell; also consider k_left; top-interview-150 0 6.0
01238 Fetching from uHunt 8.3b, DP level 4 LA 4143 - Jakarta08; offset technique 0.0
12870 Fetching from uHunt 8.3b, DP level 4 LA 6848 - Bangkok14; split DP for fishing and nourishing; try all combination of K fishing + 2K nourishing events 0.0
coke coke 8.3b, DP level 4 drop parameter n1; recover it from b (number of coke bought), n5, and n10; also available at UVa 10626 - Buying Coke 304 5.6
companypicnic companypicnic 8.3b, DP level 4 s: (name, has_been_matched); DP weighted matching (both cardinality and weight) on Tree 200 5.0
lc0790 to replace with LeetCode link soon... 8.3b, DP level 4 s: (n, got_hole); t: depends whether there is a hole (due to a Triomino) or not; simple profile DP; leetcode-75 0 4.0
rollercoasterfun rollercoasterfun 8.3b, DP level 4 s: (T); split DPs when b = 0 and when b != 0 101 7.7
11125 Fetching from uHunt 8.3c, Counting Paths, Harder counting paths in implicit DAG; the implicit DAG is not trivial; 8 parameters 0.0
11375 Fetching from uHunt 8.3c, Counting Paths, Harder counting paths in DAG; 2 parameters; be careful that we can create a 0 with 6 sticks; need to use Java BigInteger 0.0
11432 Fetching from uHunt 8.3c, Counting Paths, Harder counting paths in DAG; the implicit DAG is not trivial; 6 parameters 0.0
countcircuits countcircuits 8.3c, Counting Paths, Harder s: (id, cur_x, cur_y); t: skip or use this vector; use offset technique to avoid negative indices 278 5.8
favourable favourable 8.3c, Counting Paths, Harder s: (cur_page); t: jump to one of the 3 sections 304 4.5
pachinkoprobability pachinkoprobability 8.3c, Counting Paths, Harder s: (pos); DAG modeling; long long 113 5.8
01099 Fetching from uHunt 8.3d, DP with Bitmask LA 4794 - WorldFinals Harbin10; s: (w; bitmask); recover parameter value h 0.0
01252 Fetching from uHunt 8.3d, DP with Bitmask LA 4643 - Tokyo09; DP, s: (mask1, mask2) where mask1/mask2 describes the features/answers, respectively 0.0
10911 Fetching from uHunt 8.3d, DP with Bitmask the intro problem of this book; DP with bitmask; weighted MCM; small complete weighted graph 0.0
hidingchickens hidingchickens 8.3d, DP with Bitmask weighted MCM; small complete weighted graph; make fox goes back to the killing spot first after hiding one or two chicke... 89 5.7
lc3530 to replace with LeetCode link soon... 8.3d, DP with Bitmask s: (mult, mask); t: go to unprocessed vertex if the topological order is not violated 0 6.0
narrowartgallery narrowartgallery 8.3d, DP with Bitmask interesting DP; s: (row, state_of_prev_row, k_left) 1417 2.8
pebblesolitaire2 pebblesolitaire2 8.3d, DP with Bitmask backtracking suffices for Kattis - pebblesolitair; but this version needs extra memoization 400 3.6
00820 Fetching from uHunt 8.4a, Network Flow, Standard LA 5220 - WorldFinals Orlando00; very basic max flow problem 0.0
11167 Fetching from uHunt 8.4a, Network Flow, Standard many edges in the flow graph; compress the capacity-1 edges when possible; use Dinic's 0.0
11418 Fetching from uHunt 8.4a, Network Flow, Standard two layers of graph matching (not really bipartite matching); use max flow solution 0.0
12873 Fetching from uHunt 8.4a, Network Flow, Standard LA 6851 - Bangkok14; assignment problem; similar to UVa 00259, 11045, and 10092; use Dinic's 0.0
maxflow maxflow 8.4a, Network Flow, Standard standard max flow problem for practice; print edges used in the max flow 531 6.3
mazemovement mazemovement 8.4a, Network Flow, Standard use gcd for all pairs of vertices to construct the flow graph; then it is just a standard max flow problem 135 4.4
mincut mincut 8.4a, Network Flow, Standard standard min cut problem for practice; print vertices reachable from source s after max flow 293 4.1
00563 Fetching from uHunt 8.4b, Network Flow, Variants check whether the maximum number of independent paths on the flow graph equals to b banks 0.0
11380 Fetching from uHunt 8.4b, Network Flow, Variants max flow modeling with vertex capacities; similar to UVa 12125 0.0
11757 Fetching from uHunt 8.4b, Network Flow, Variants creative problem about min cut; build the flow graph with a bit of simple geometry involving circle; then find the min c... 0.0
11765 Fetching from uHunt 8.4b, Network Flow, Variants interesting min cut variant 0.0
avoidingtheapocalypse avoidingtheapocalypse 8.4b, Network Flow, Variants interesting max flow modeling; blow the vertices based on time 191 4.4
thekingofthenorth thekingofthenorth 8.4b, Network Flow, Variants interesting min cut problem 193 5.0
transportation transportation 8.4b, Network Flow, Variants max flow with vertex capacities 165 5.6
00989 Fetching from uHunt 8.6a, NP-hard/C, small, E classic SUDOKU puzzle; the small 9x9 instance is solvable with backtracking with pruning; use bitmask to speed up 0.0
11088 Fetching from uHunt 8.6a, NP-hard/C, small, E similar to UVa 10911 but partitioning of three persons to one team; PARTITION-INTO-TRIANGLES 0.0
12455 Fetching from uHunt 8.6a, NP-hard/C, small, E SUBSET-SUM; try all; see the harder UVa 12911 that requires meet in the middle 0.0
equalsumseasy equalsumseasy 8.6a, NP-hard/C, small, E PARTITION; generate all possible subsets with bitmask; use set to record which sums have been computed 474 2.3
flowfree flowfree 8.6a, NP-hard/C, small, E brute force combination 3^10 or 4^8; then LONGEST-PATH problem on non DAG between two end points of the same color 109 4.4
font font 8.6a, NP-hard/C, small, E count number of possible SET-COVERs; use 2^N backtracking; but use bitmask to represent small set of covered letters 199 4.2
socialadvertising socialadvertising 8.6a, NP-hard/C, small, E MIN-DOMINATING-SET/MIN-SET-COVER; n ≤ 20; use compact Adjacency Matrix technique 59 5.1
01098 Fetching from uHunt 8.6b, NP-hard/C, small, H LA 4793 - WorldFinals Harbin10; HAMILTONIAN-TOUR; backtracking+pruning; meet in the middle 0.0
11095 Fetching from uHunt 8.6b, NP-hard/C, small, H optimization version of Min Vertex Cover on general graph which is NP-Hard 0.0
12911 Fetching from uHunt 8.6b, NP-hard/C, small, H SUBSET-SUM; we cannot use DP as 1 ≤ N ≤ 40 and -10^9 ≤ T ≤ 10^9; use meet in the middle 0.0
beanbag beanbag 8.6b, NP-hard/C, small, H SET-COVER problem; T farmers can collude to give Jack the hardest possible subset of beans to be given freely to Jack 119 4.9
busplanning busplanning 8.6b, NP-hard/C, small, H MIN-CLIQUE-COVER; DP bitmask over sets 91 5.4
lc0015 to replace with LeetCode link soon... 8.6b, NP-hard/C, small, H one possible way is to hash all numbers and try all-pairs; avoid duplicates; top-100-liked; top-interview-150 0 4.0
programmingteamselection programmingteamselection 8.6b, NP-hard/C, small, H PARTITION-INTO-TRIANGLES; prune if #students % 3 != 0; generate up to m/3 teams; backtracking with memo 64 7.2
01347 Fetching from uHunt 8.6c, NP-hard/C, special, E LA 3305 - SoutheasternEurope05; this is the pure version of Bitonic TSP problem; you may want to start from here 0.0
10859 Fetching from uHunt 8.6c, NP-hard/C, special, E Min-Vertex-Cover; on several trees; maximize number of edges with its two endpoints covered 0.0
11159 Fetching from uHunt 8.6c, NP-hard/C, special, E MAX-INDEPENDENT-SET; on Bipartite Graph; ans equals to its MCBM 0.0
bilateral bilateral 8.6c, NP-hard/C, special, E MIN-VERTEX-COVER on Bipartite Graph; MCBM; Konig's theorem that can handle the 1009 case correctly 43 6.5
europeantrip europeantrip 8.6c, NP-hard/C, special, E STEINER-TREE with 3 terminal vertices and up to 1 Steiner point; we can use two ternary searches 297 3.3
lc0198 to replace with LeetCode link soon... 8.6c, NP-hard/C, special, E MWIS; on line graph; simple DP; leetcode-75; top-100-liked; top-interview-150 0 4.0
reactivity reactivity 8.6c, NP-hard/C, special, E verify if a HAMILTONIAN-PATH exists in the DAG; find one topological sort of the DAG; verify if it is the only one in li... 280 4.0
01086 Fetching from uHunt 8.6d, NP-hard/C, special, H LA 4452 - WorldFinals Stockholm09; can be modeled as a 2-SAT problem 0.0
01096 Fetching from uHunt 8.6d, NP-hard/C, special, H LA 4791 - WorldFinals Harbin10; Bitonic TSP variant; print the actual path 0.0
01184 Fetching from uHunt 8.6d, NP-hard/C, special, H LA 2696 - Dhaka02; MPC on DAG ~ MCBM 0.0
01212 Fetching from uHunt 8.6d, NP-hard/C, special, H LA 3483 - Hangzhou05; MWIS on Bipartite Graph 0.0
jailbreak jailbreak 8.6d, NP-hard/C, special, H STEINER-TREE; grid; BFS from 3 vertices: 'outside' and 2 prisoners (open doors independently or meet a Steiner point fir... 130 4.8
ridofcoins ridofcoins 8.6d, NP-hard/C, special, H not the minimizing COIN-CHANGE problem; but the maximizing one; greedy pruning; complete search on much smaller instance 94 7.9
wedding wedding 8.6d, NP-hard/C, special, H can be modeled as a 2-SAT problem; also available at UVa 11294 - Wedding 36 6.7
00714 Fetching from uHunt 8.7a, BSTA+Other, Easier binary search the answer and greedy 0.0
11262 Fetching from uHunt 8.7a, BSTA+Other, Easier binary search the answer and MCBM; similar with UVa 10804 0.0
12097 Fetching from uHunt 8.7a, BSTA+Other, Easier binary search the answer and geometric formula 0.0
arrivingontime arrivingontime 8.7a, BSTA+Other, Easier BSTA: the latest starting time; use Dijkstra's to compute whether we can still arrive at meeting point on time 79 6.3
charlesincharge charlesincharge 8.7a, BSTA+Other, Easier BSTA: max edge that Charles can use; SSSP from 1 to $N$ passing through edges that do not exceed that; is it OK? 149 4.8
programmingtutors programmingtutors 8.7a, BSTA+Other, Easier +perfect MCBM 161 3.7
01221 Fetching from uHunt 8.7b, BSTA+Other, Harder LA 3795 - Tehran06; +MCBM 0.0
10537 Fetching from uHunt 8.7b, BSTA+Other, Harder +Dijkstra's on State-Space graph 0.0
10983 Fetching from uHunt 8.7b, BSTA+Other, Harder binary search the answer and max flow 0.0
catandmice catandmice 8.7b, BSTA+Other, Harder BSTA: the initial velocity of Cartesian Cat; DP TSP to verify if the cat can catch all mice in the shortest possible tim... 141 6.8
enemyterritory enemyterritory 8.7b, BSTA+Other, Harder MSSP from all enemy vertices; BSTA, run BFS from (xi, yi) to (xr, yr) avoiding vertices that are too close to any enemy 66 4.2
gravamen gravamen 8.7b, BSTA+Other, Harder BSTA + max flow 45 6.1
wifi wifi 8.7b, BSTA+Other, Harder +greedy; also available at UVa 11516 - WiFi 214 4.3
11960 Fetching from uHunt 8.7c, Fast DS+Other, Easier modified Sieve; number of divisors; static Range Maximum Query; use Sparse Table data structure 0.0
12318 Fetching from uHunt 8.7c, Fast DS+Other, Easier brute force with unordered_set 0.0
12460 Fetching from uHunt 8.7c, Fast DS+Other, Easier a simple BFS problem; use set of string data structure to speed up the check if a word is inside dictionary 0.0
busnumbers2 busnumbers2 8.7c, Fast DS+Other, Easier complete search; use unordered_map 377 3.0
quickscope quickscope 8.7c, Fast DS+Other, Easier use stack of sets and hash table of stacks 1326 3.9
selfsimilarstrings selfsimilarstrings 8.7c, Fast DS+Other, Easier complete search as the string is short; frequency counting; use unordered_map; repetition 181 3.5
undetected undetected 8.7c, Fast DS+Other, Easier brute force; simple geometry; UFDS 274 3.9
00843 Fetching from uHunt 8.7d, Fast DS+Other, Harder backtracking; try mapping each letter to another letter in alphabet; use Trie data structure for speed up 0.0
11474 Fetching from uHunt 8.7d, Fast DS+Other, Harder UFDS; connect all tree branches; connect two reachable trees (use geometry); connect trees that can reach doctor 0.0
11525 Fetching from uHunt 8.7d, Fast DS+Other, Harder use Fenwick Tree and binary search the answer to find the lowest index i that has RSQ(1;i) = Si 0.0
dictionaryattack dictionaryattack 8.7d, Fast DS+Other, Harder time limit is generous; you can generate all possible password with just 3 swaps; store in sets 101 7.0
doublets doublets 8.7d, Fast DS+Other, Harder s: (string); BFS; use trie to quickly identify neighbor that is one Hamming distance away; also available at UVa 10150 -... 56 8.3
magicallights magicallights 8.7d, Fast DS+Other, Harder LA 7487 - Singapore15; flatten the tree with DFS; use Fenwick Tree for Range Odd Query; use long long 309 5.4
sparklesseven sparklesseven 8.7d, Fast DS+Other, Harder seven nested loops with fast DS 52 5.7
10012 Fetching from uHunt 8.7e, Geometry+CS try all 8! permutations; Euclidean dist 0.0
11227 Fetching from uHunt 8.7e, Geometry+CS brute force; collinear test 0.0
collidingtraffic collidingtraffic 8.7e, Geometry+CS try all pairs of boats; 0.0 if one pair collide; or, use a quadratic equation; also available at UVa 11574 - Colliding T... 48 5.0
cranes cranes 8.7e, Geometry+CS circle-circle intersection; backtracking or brute force subsets with bitmask; also available at UVa 11515 - Cranes 137 3.8
doggopher doggopher 8.7e, Geometry+CS complete search; Euclidean distance dist; also available at UVa 10310 - Dog and Gopher 119 2.5
lc0149 to replace with LeetCode link soon... 8.7e, Geometry+CS identical with UVa 11227; top-interview-150 0 6.0
11008 Fetching from uHunt 8.7f, Geometry+Other collinear test; DP bitmask 0.0
12322 Fetching from uHunt 8.7f, Geometry+Other first; use atan2 to convert angles to 1D intervals; then sort it and use a greedy scan to get the answer 0.0
findinglines findinglines 8.7f, Geometry+Other randomly pick two points; there is a good chance that 20% or more points are on that line defined by those two points 209 6.3
humancannonball humancannonball 8.7f, Geometry+Other build the travel time graph with Euclidean distance computations; use Floyd-Warshall 757 2.2
lc0976 to replace with LeetCode link soon... 8.7f, Geometry+Other sort nums in non-increasing order; do triangle inequality checks; programming-skills 0 2.0
walkway walkway 8.7f, Geometry+Other we can build the graph and compute area of trapezoid using simple geometry; SSSP on weighted graph; Dijkstra's 190 3.4
00393 Fetching from uHunt 8.7g, Graph+Other build the small visibility graph with line segment intersection checks; run Floyd-Warshall routine to get the answer 0.0
01092 Fetching from uHunt 8.7g, Graph+Other LA 4787 - WorldFinals Harbin10; compress graph; traversal from exit with S/W direction; inclusion-exclusion 0.0
12159 Fetching from uHunt 8.7g, Graph+Other LA 4407 - KualaLumpur08; use simple CCW tests (geometry) to build the bipartite graph; MCBM 0.0
crowdcontrol crowdcontrol 8.7g, Graph+Other maximin path problem; MST; DFS from train station to BAPC; block unused edges 100 3.8
gears2 gears2 8.7g, Graph+Other graph reachability test; cycle with equal ratio is actually OK; math fraction 95 3.7
gridmst gridmst 8.7g, Graph+Other Singapore15 preliminary; rectilinear MST problem; small 2D grid; multi-sources BFS to construct short edges; Kruskal's t... 245 7.4
01069 Fetching from uHunt 8.7h, Mathematics+Other LA 4119 - WorldFinals Banff08; string parsing, divisibility of polynomial, brute force, and modPow 0.0
11282 Fetching from uHunt 8.7h, Mathematics+Other derangement and binomial coefficient; Big Integer 0.0
emergency emergency 8.7h, Mathematics+Other the problem is posed as an SSSP problem on special graph; but turns out a simple formula solves the problem; Big Integer 319 3.7
industrialspy industrialspy 8.7h, Mathematics+Other brute force recursive bitmask with prime check; also available at UVa 12218 - An Industrial Spy 556 3.3
lc1071 to replace with LeetCode link soon... 8.7h, Mathematics+Other divisibility; on string; leetcode-75 0 2.0
megainversions megainversions 8.7h, Mathematics+Other a bit of combinatorics; use Fenwick Tree to compute smaller/larger numbers quickly 333 5.0
ontrack ontrack 8.7h, Mathematics+Other DFS on Tree; the input is a tree, we can try all possible junctions as the critical junction 156 4.1
00976 Fetching from uHunt 8.7i, Graph+DP flood fill to separate North and South banks; compute the cost of installing a bridge at each column; DP 0.0
10937 Fetching from uHunt 8.7i, Graph+DP BFS -> APSP information for TSP; then DP or backtracking 0.0
11324 Fetching from uHunt 8.7i, Graph+DP LONGEST-PATH on DAG; first, transform the graph into DAG of its SCCs; toposort 0.0
11331 Fetching from uHunt 8.7i, Graph+DP bipartite graph checks; compute size of left/right sets per bipartite component; DP SUBSET-SUM 0.0
treasurediving treasurediving 8.7i, Graph+DP SSSP from source and all idol positions; TSP-like but there is a knapsack style parameter 'air_left'; use backtracking 87 7.3
walkforest walkforest 8.7i, Graph+DP counting paths in DAG; build the DAG; Dijkstra's from 'home'; also available at UVa 10917 - A Walk Through the Forest 245 4.4
10533 Fetching from uHunt 8.7j, Other+DP 1D RSQ/RMQ sieve; check if a prime is a digit prime; DP 1D range sum 0.0
10891 Fetching from uHunt 8.7j, Other+DP 1D RSQ/RMQ Double DP; 1D RSQ plus another DP to evaluate decision tree; s: (i, j); try all splitting points; minimax 0.0
11032 Fetching from uHunt 8.7j, Other+DP 1D RSQ/RMQ observation: sod(i) can be only from 1 to 63; use 1D Range Sum Query for fun(a; b) 0.0
11408 Fetching from uHunt 8.7j, Other+DP 1D RSQ/RMQ need 1D Range Sum Query 0.0
centsavings centsavings 8.7j, Other+DP 1D RSQ/RMQ 1D RSQ DP for sum of prices from [i..j]; round up/down; s: (idx, d_left); t: try all positioning of the next divider 531 4.6
dvoniz dvoniz 8.7j, Other+DP 1D RSQ/RMQ involving 1D RSQ DP; binary search the answer 47 7.1
program program 8.7j, Other+DP 1D RSQ/RMQ somewhat like Sieve of Eratosthenes initially and 1D RSQ DP speedup at the end 89 7.7
00295 Fetching from uHunt 8.7k, Three++ Components, E BSTA x: if the person has diameter x, can he go from left to right? graph connectivity; similar with UVa 10876 0.0
01250 Fetching from uHunt 8.7k, Three++ Components, E LA 4607 - SoutheastUSA09; geometry; SSSP on DAG -> DP; DP 1D range sum 0.0
beeproblem beeproblem 8.7k, Three++ Components, E transform bee grid into 2D grid; compute size of each CCs; sort; greedy 156 4.9
gettingthrough gettingthrough 8.7k, Three++ Components, E BSTA+graph connectivity; Union-Find; similar to UVa 00295 51 7.2
lc2300 to replace with LeetCode link soon... 8.7k, Three++ Components, E sort potions; try all spells and BSTA each time; leetcode-75 0 4.0
researchproductivityindex researchproductivityindex 8.7k, Three++ Components, E sort papers by decreasing probability; brute force k and greedily submit k best papers; DP probability; keep max 358 3.2
00811 Fetching from uHunt 8.7l, Three++ Components, H LA 5211 - WorldFinals Eindhoven99; get CH and perimeter of polygon; generate all subsets iteratively with bitmask 0.0
01040 Fetching from uHunt 8.7l, Three++ Components, H LA 3271 - WorldFinals Shanghai05; try all subsets of 2^20 cities; MST; complex output formatting 0.0
01079 Fetching from uHunt 8.7l, Three++ Components, H LA 4445 - WorldFinals Stockholm09; iterative complete search (permutation); BSTA + greedy 0.0
carpool carpool 8.7l, Three++ Components, H Floyd-Warshall/APSP; iterative brute force subset and permutation; DP; also available at UVa 11288 - Carpool 40 6.4
clockpictures clockpictures 8.7l, Three++ Components, H sort angles; compute 'string' of differences of adjacent angles (use modulo); min lexicographic rotation; use SA or KMP 463 5.5
guessthenumbers guessthenumbers 8.7l, Three++ Components, H brute force permute up to 5!; recursive string parsing (simple BNF); also available at UVa 12392 - Guess the Numbers 64 8.5
00588 Fetching from uHunt 9.artg, Art Gallery cutPolygon 0.0
01304 Fetching from uHunt 9.artg, Art Gallery LA 2512 - SouthEasternEurope02; cutPolygon and area of polygon 0.0
01571 Fetching from uHunt 9.artg, Art Gallery LA 3617 - Yokohama06; cutPolygon 0.0
10078 Fetching from uHunt 9.artg, Art Gallery isConvex 0.0
00652 Fetching from uHunt 9.asta, A* or IDA* classic sliding block 8-puzzle; IDA* 0.0
00656 Fetching from uHunt 9.asta, A* or IDA* we can use IDDFS with pruning 0.0
10181 Fetching from uHunt 9.asta, A* or IDA* similar with UVa 652 but larger (now 15 instead of 8); we can use IDA* 0.0
11163 Fetching from uHunt 9.asta, A* or IDA* another puzzle game solvable with IDA* 0.0
joggingtrails joggingtrails 9.chi1, Chinese Postman basic Chinese Postman Problem; also available at UVa 10296 - Jogging Trails 75 5.0
00756 Fetching from uHunt 9.chi2, Chinese Remainder CRT or brute force 0.0
chineseremainder chineseremainder 9.chi2, Chinese Remainder basic CRT; 2 linear congruences; Big Integer 343 5.4
generalchineseremainder generalchineseremainder 9.chi2, Chinese Remainder general CRT; 2 linear congruences 362 3.7
granica granica 9.chi2, Chinese Remainder CRT; GCD of all N differences of 2 numbers 95 6.2
heliocentric heliocentric 9.chi2, Chinese Remainder CRT or brute force 1030 1.8
remainderreminder remainderreminder 9.chi2, Chinese Remainder a bit of brute force + sorting; generalized CRT 124 5.2
10245 Fetching from uHunt 9.clos, Closest Pair classic 0.0
11378 Fetching from uHunt 9.clos, Closest Pair also a closest pair problem 0.0
closestpair1 closestpair1 9.clos, Closest Pair classic closest pair problem - the easier one 269 5.7
10165 Fetching from uHunt 9.comb, Comb Game Theory Nim game; application of Sprague-Grundy theorem 0.0
11311 Fetching from uHunt 9.comb, Comb Game Theory there are 4 heaps; Nim sum 0.0
01266 Fetching from uHunt 9.cons, Construction LA 3478 - LatinAmerica05; follow the given construction strategy 0.0
10741 Fetching from uHunt 9.cons, Construction similar idea as 2D Magic Square; but now in 3D; just follow the given construction strategy 0.0
base2palindrome base2palindrome 9.cons, Construction construct all possible base 2 palindromes; put into a set to remove duplicates and maintain order; output the M-th one 385 4.4
espressobucks espressobucks 9.cons, Construction easy brute force construction; small nxm; not about Min-Vertex-Cover 159 2.4
exofficio exofficio 9.cons, Construction we can use BFS spanning tree from center of the grid; be careful of corner cases 41 7.5
plowking plowking 9.cons, Construction greedy construction; reverse MST problem 92 3.2
poplava poplava 9.cons, Construction actually there is a rather simple construction algorithm to achieve the required requirement 105 3.4
10506 Fetching from uHunt 9.debr, De Bruijn Sequence any valid solution is AC; generate all possible next digit (up to base 10/digit [0..9]); check if it is still a valid Ou... 0.0
11439 Fetching from uHunt 9.edmo, Edmonds' Matching BSTA (the minimum weight); use it to reconstruct the graph; perfect matching on medium-sized general graph 0.0
10934 Fetching from uHunt 9.eggd, Egg Dropping Puzzle Egg dropping puzzle; interesting DP; try all possible answers 0.0
batteries batteries 9.eggd, Egg Dropping Puzzle Egg dropping puzzle with just 2 batteries; special case 146 3.6
powereggs powereggs 9.eggd, Egg Dropping Puzzle Egg dropping puzzle; similar to UVa 10934 92 5.2
golfbot golfbot 9.fast, Fast Fourier Trans count frequencies dist of each reachable distance in one shot; use FFT to multiply dist*dist; count distances reachable ... 133 6.1
polymul2 polymul2 9.fast, Fast Fourier Trans basic polynomial multiplication problem that needs an O(n log n) algorithm; also see Kattis - polymul1 227 6.8
01645 Fetching from uHunt 9.form, Formulas/Theorems LA 6368 - Chengdu12; number of rooted trees with n vertices in which vertices at the same level have the same degree 0.0
11719 Fetching from uHunt 9.form, Formulas/Theorems count the number of spanning tree in a complete bipartite graph; use Java BigInteger 0.0
12786 Fetching from uHunt 9.form, Formulas/Theorems similar to UVa 10720 and 11414; Erdos-Gallai Theorem 0.0
13108 Fetching from uHunt 9.form, Formulas/Theorems Moser's circle; the formula is hard to derive; g(n) = nC4 + nC2 + 1 0.0
houseofcards houseofcards 9.form, Formulas/Theorems number of cards for certain height h is h * (3*h + 1) / 2; use Python to handle Big Integer 432 3.4
janitortroubles janitortroubles 9.form, Formulas/Theorems Brahmagupta's formula 745 1.5
sjecista sjecista 9.form, Formulas/Theorems number of intersections of diagonals in a convex polygon 581 1.9
00684 Fetching from uHunt 9.gaus, Gauss Elimination modified Gaussian elimination to find (integral) determinant of a square matrix 0.0
11319 Fetching from uHunt 9.gaus, Gauss Elimination solve the system of the first 7 linear equations; then use all 1500 equations for 'smart sequence' checks 0.0
seti seti 9.gaus, Gauss Elimination n equations and n unknowns; but there are division under modulo, so use Gaussian elimination with modular multiplicative... 52 3.1
pizza pizza 9.grad, Gradient Descent gradient descent 252 4.5
amazing amazing 9.inte, Interactive Problem run DFS and react based on the output of the program 215 5.2
askmarilyn askmarilyn 9.inte, Interactive Problem the famous Monty hall problem in interactive format 135 4.2
blackout blackout 9.inte, Interactive Problem interactive game theory; block one row; mirror jury's move 129 3.1
crusaders crusaders 9.inte, Interactive Problem another nice interactive problem about binary search 34 7.4
guess guess 9.inte, Interactive Problem interactive problem; binary search 1682 2.7
01045 Fetching from uHunt 9.kuhn, Kuhn-Munkres LA 3276 - WorldFinals Shanghai05; try all configurations; weighted matching; pick the best; Kuhn-Munkres 0.0
10746 Fetching from uHunt 9.kuhn, Kuhn-Munkres min weighted bipartite matching 0.0
10888 Fetching from uHunt 9.kuhn, Kuhn-Munkres BFS/SSSP; min weighted bipartite matching 0.0
11553 Fetching from uHunt 9.kuhn, Kuhn-Munkres brute force; DP bitmask; or Hungarian 0.0
aqueducts aqueducts 9.kuhn, Kuhn-Munkres build bipartite graph; weighted MCBM; Hungarian 51 6.0
engaging engaging 9.kuhn, Kuhn-Munkres LA 8437 - HoChiMinhCity17; Hungarian; print solution 135 5.8
cheeseifyouplease cheeseifyouplease 9.line, Linear Programming simple Linear Programming problem; use Simplex 51 3.3
maximumrent maximumrent 9.line, Linear Programming basic Linear Programming problem with integer output; we can use simplex algorithm or another simpler solution 241 3.1
10938 Fetching from uHunt 9.lowe, Lowest Common Anc basic LCA problem 0.0
12238 Fetching from uHunt 9.lowe, Lowest Common Anc similar to UVa 10938 0.0
chewbacca chewbacca 9.lowe, Lowest Common Anc complete short k-ary tree; binary heap indexing; LCA 186 3.6
00348 Fetching from uHunt 9.matr, Matrix Chain Mult DP; s(i, j); output the optimal solution; the optimal sequence is not unique 0.0
10594 Fetching from uHunt 9.minc, Min Cost (Max) Flow basic min cost max flow problem 0.0
10806 Fetching from uHunt 9.minc, Min Cost (Max) Flow send 2 edge-disjoint flows with min cost 0.0
11301 Fetching from uHunt 9.minc, Min Cost (Max) Flow modeling; vertex capacity; MCMF 0.0
12821 Fetching from uHunt 9.minc, Min Cost (Max) Flow similar to UVa 10806 0.0
catering catering 9.minc, Min Cost (Max) Flow LA 7152 - WorldFinals Marrakech15; MCMF modeling 246 3.9
mincostmaxflow mincostmaxflow 9.minc, Min Cost (Max) Flow very basic MCMF problem; good starting point 232 5.3
ragingriver ragingriver 9.minc, Min Cost (Max) Flow MCMF; unit capacity and unit cost 96 7.1
00120 Fetching from uHunt 9.panc, Pancake Sorting greedy pancake sorting 0.0
lc0969 to replace with LeetCode link soon... 9.panc, Pancake Sorting the easier form of Pancake Sorting; flip largest to top (index 1), then to target; at most 2*n flips 0 4.0
11476 Fetching from uHunt 9.poll, Pollard's rho basic integer factorization problem that requires Pollard's rho algorithm 0.0
lc0169 to replace with LeetCode link soon... 9.rand, Randomized Algo try a random number and see if it is the majority element, repeat; top-100-liked; top-interview-150 0 2.0
lc0398 to replace with LeetCode link soon... 9.rand, Randomized Algo separate chaining; record indices of each value; randomly return a valid index 0 4.0
lc0519 to replace with LeetCode link soon... 9.rand, Randomized Algo randomly pick (r, c) inside the grid; repeat if it has been taken 0 4.0
cardboardcontainer cardboardcontainer 9.sqrt, Square Root Decomp two out of L, W, and H must be ≤ sqrt(V); brute force L and W in sqrt(V)*sqrt(V) and test if V is divisible by (L*W) 141 2.5
modulodatastructures modulodatastructures 9.sqrt, Square Root Decomp basic problem that can be solved with Square Root Decomposition technique 277 4.6
00254 Fetching from uHunt 9.towe, Tower of Hanoi define a recursive formula 0.0
10017 Fetching from uHunt 9.towe, Tower of Hanoi classical problem 0.0
10254 Fetching from uHunt 9.towe, Tower of Hanoi find pattern; use Java BigInteger 0.0

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