Selected problems

We selected a few problems, which we think are good training material for programming contests. Each problem is assigned to some category and also to some level. We recommend to start with level 1 in order to make sure you know the basic tools. Then continue with level 2, 3 and finally 4. But you have guessed that, right?

Hide chapter hint.

ad hocAdvanced ASCII Cubes [tju] [zju]
ad hoc☆☆☆☆Australian Voting [tju]
ad hoc☆☆☆☆Babel Towers [tju]
ad hoc☆☆☆☆Blood Type [tju]
ad hoc☆☆☆☆Bullseye [codejam]
ad hocCity hall [tju]
ad hoc☆☆☆☆Common Item [tju]
ad hoc☆☆☆☆Cryptoquote [tju]
ad hoc☆☆☆☆DNA Sorting [tju]
ad hoc☆☆☆☆European railroad tracks [tju]
ad hoc☆☆☆☆Giant Screen [tju]
ad hoc☆☆☆☆Huffman Trees [tju] [zju]
ad hoc☆☆☆☆Interpreter [tju]
ad hoc☆☆☆☆Knights In The Zombie Land [onlinejudge]
ad hocLC Display [tju]
ad hoc☆☆☆☆Matrix Swapping II [tju]
ad hocMine Sweeper [tju]
ad hoc☆☆☆Poker Hands [onlinejudge]
ad hoc☆☆☆☆The Trip [tju]
ad hoc☆☆☆☆Total flow [tju]
ad hoc☆☆☆☆X-Express [onlinejudge]
anagrams☆☆Anagram checker [onlinejudge]
anagrams☆☆Anagram Groups [poj] [tju]
arithmetic☆☆☆☆Factorvisors [onlinejudge]
backtracking☆☆☆☆Channel Allocation [tju]
backtracking☆☆☆☆Minimal length addition chain [codility]
backtracking☆☆Mirror Maze [onlinejudge]
backtracking☆☆Sudoku (16x16) [tju] [spoj]
backtracking☆☆Sudoku (9x9) [tju] [spoj]
backtracking☆☆☆☆The Triangle Game [zju]
bellman ford☆☆☆☆Haunted graveyard [spoj]
bellman ford☆☆Negative Cycles [spoj]
bellman ford☆☆Roads in Berland [spoj]
BFS☆☆Hike on a Graph [spoj]
BFS☆☆☆☆Kisu Pari Na 2 [onlinejudge]
BFS☆☆☆☆Knight Moves [poj]
BFS☆☆Ricochet Robots [onlinejudge]
BFS☆☆Traffic Jam [icpcarchive] [tju]
biconnected components☆☆☆☆Street Directions [tju]
biconnected components☆☆The Key Stations [tju]
binary search☆☆☆☆AggressiveCows [spoj]
binary search☆☆Egg Drop [codejam]
binary search☆☆Fill the cisterns [spoj]
binary search☆☆☆☆SpeedCameras [codility]
binary tree☆☆☆☆France'98 [uni-ulm] [uni-ulm]
binomial coefficients☆☆☆☆Hexagonal Routes [tju]
bipartite matching☆☆Dungeon of Death [spoj]
bipartite matching☆☆Muddy Fields [spoj]
bipartite vertex cover☆☆☆☆Playground [tju]
combinatoire☆☆☆☆Make it Manhattan [tju]
connected components☆☆The Ant [spoj]
convex hull☆☆☆☆Herding Frosh [tju]
data 1d☆☆Unique Encryption Keys [icpcarchive]
decoding☆☆☆☆Alien Numbers [codejam]
decoding☆☆☆☆All your base [codejam]
decoding☆☆☆☆Crazy Search [tju]
decoding☆☆☆☆IPNetworks [tju]
decodingProblem 3467 [tju]
DFS☆☆☆☆Caterpillar [tju]
DFS☆☆Mine [tju]
DFS☆☆☆☆Mine [tju]
DFS☆☆Playing Boogle [onlinejudge]
DFS☆☆☆☆Poor Wenwen [tju]
DFS☆☆☆☆The Die Is Cast [tju]
dictionary☆☆☆☆Incidental Points [tju]
dijkstra☆☆Almost the shortest route [tju]
dijkstra☆☆☆☆Dirt [tju]
dijkstra☆☆Dragon Maze [codejam]
dijkstra☆☆☆☆Hydrogenium [codility]
dijkstra☆☆☆☆Low Cost Air Travel [icpcarchive]
dijkstra☆☆☆☆The K-th City [tju]
dijkstra☆☆War [tju]
dilworth☆☆Stock Charts [codejam]
dilworth☆☆Taxi Cab Scheme [icpcarchive] [poj]
dilworth☆☆☆☆Wooden sticks [poj] [tju]
dinic☆☆Fast Maximum Flow [spoj]
dinic☆☆Maximum Flow [spoj]
dist grid☆☆A Famous Grid [spoj]
dynamic programming☆☆☆☆A Digging Problem [codejam]
dynamic programming☆☆☆☆Airbus vs. Boeing [onlinejudge]
dynamic programming☆☆☆☆Blocks [onlinejudge]
dynamic programming☆☆☆☆Brackets sequence [tju]
dynamic programming☆☆☆☆Bribe the Prisoners [codejam]
dynamic programming☆☆☆☆Chopstick [onlinejudge]
dynamic programming☆☆☆☆Cow Solitaire [tju]
dynamic programming☆☆Sweet and Sour Rock [spoj]
dynamic programming☆☆☆☆To The Max [tju]
eratosthene☆☆The Spiral of Primes [icpcarchive]
eulerian tour☆☆Free Tour [spoj]
eulerian tour☆☆Goldbach graphs [spoj]
expr eval☆☆☆☆Alien Language [codejam]
expr eval☆☆Boolean Expression [tju]
expr eval☆☆Cells [spoj]
expr eval☆☆☆☆Compile Error [spoj]
expr eval☆☆☆☆Matrix Chain Multiplication [poj]
expr eval☆☆☆☆Simplified Lambda-evaluations [tju]
expr eval☆☆Spreadsheet [onlinejudge] [tju]
expr eval☆☆☆Strange Expression [tju]
fast exponentiation☆☆Modex [onlinejudge]
fast exponentiation☆☆Tiling a Grid With Dominoes [tju] [spoj]
finite automata☆☆☆☆Language recognition [onlinejudge]
floyd warshall☆☆☆☆Edgetown's Traffic Jams [onlinejudge]
floyd warshall☆☆☆☆Stockbroker Grapevine [tju]
floyd warshall☆☆☆☆Word Ladders [tju]
gale shapley☆☆Stable Marriage Problem [spoj]
gauss jordan☆☆Ars Longa [onlinejudge] [icpcarchive]
geometryCenter of Mass [codejam]
geometry☆☆☆☆Chocolate Chip Cookies [tju]
geometry☆☆☆☆Divide the land [onlinejudge]
geometry☆☆☆November Rain [poj] [tju]
geometry☆☆☆☆Shrinking Polygons [icpcarchive]
graph01☆☆Finding Nemo [tju] [zju]
greatest monochromatic rectangle☆☆☆☆Largest Submatrix of All 1’s [pku] [poj]
greedy☆☆☆☆ABCD [spoj]
greedy☆☆☆☆Airport Walkways [codejam]
greedyColor A Tree [tju]
greedy☆☆☆☆Enter the dragon [icpcarchive]
greedy☆☆☆☆Feel Good [tju]
greedy☆☆☆☆Flags [codility]
greedy☆☆☆☆Homework [tju]
greedy☆☆Minimal Coverage [onlinejudge]
greedy☆☆Minimum Scalar Product [codejam]
greedyNovice41 [spoj]
greedy☆☆☆☆Prefix Suffix Set [codility]
grid☆☆☆☆Always Turn Left [codejam]
grid☆☆☆☆Number Steps [tju]
grid☆☆☆☆Spiral of Numbers [onlinejudge]
huffman☆☆Huffman Trees [poj]
huffman☆☆Variable Radix Huffman Encoding [spoj]
intervals cover☆☆Radar Installation [tju]
k-sum☆☆4 Values whose Sum is 0 [poj]
knuth morris pratt☆☆A Needle in the Haystack [spoj]
knuth morris pratt☆☆Find the maximal product of string prefixes [codility]
kruskal☆☆Networking [tju]
kuhn munkres☆☆Selfish Cities [spoj]
levenshtein☆☆Advanced Edit Distance [spoj]
levenshtein☆☆Edit distance [spoj]
levenshtein☆☆The Separator in Grid [tju]
longest common subsequence☆☆Common Subsequence [tju]
longest common subsequence☆☆Longest Common Subsequence [spoj]
longest increasing subsequence☆☆Easy Longest Increasing Subsequence [spoj]
longest increasing subsequence☆☆☆☆Is Bigger Smarter? [tju]
longest increasing subsequence☆☆☆☆Longest Ordered Subsequence [tju]
longest path☆☆☆☆Ascending paths [codility]
longest path in a dag☆☆☆☆Edit Step Ladders [tju]
longest path in a dag☆☆☆☆Stacking Boxes [onlinejudge]
longest path in a tree☆☆Labyrinth [spoj] [tju]
longest path in a tree☆☆☆☆Labyrinth [tju]
longest path in a tree☆☆Longest path in a tree [spoj]
longuest common subsequence☆☆☆☆Greatest Common Increasing Subsequence [tju] [pku]
lowest common ancestor☆☆City Driving [stanford] [stanford]
manacher☆☆Casting Spells [icpcarchive]
manacher☆☆Longest Palindrome [onlinejudge]
matrix chain mult☆☆Mixtures [spoj]
matrix chain mult☆☆Optimal Array Multiplication Sequence [tju]
matrix chain mult☆☆The safe secret [onlinejudge]
maximum flow☆☆Crime Wave [onlinejudge] [icpcarchive]
maximum flow☆☆☆☆Down Went the Titanic [onlinejudge]
maximum interval intersection☆☆☆☆Magic Sticks Again [tju]
maximum matching☆☆☆☆Councilling [onlinejudge]
maximum matching☆☆☆☆Courses [tju]
median☆☆☆☆Pizza Delivery [tju] [zju]
min mean cycle☆☆Word Rings [spoj]
next permutation☆☆Anagram [onlinejudge]
next permutation☆☆GREAT+SWERC=PORTO [onlinejudge]
pattern matching☆☆☆☆Barcode of Judgment [livearchive]
permutation☆☆☆☆Crypto Columns [tju]
powerstring☆☆Period [spoj]
powerstring☆☆Power strings [onlinejudge]
predictive text☆☆T9 [poj]
prefix tree☆☆☆☆Phone Numbers [poj]
prim☆☆☆☆Freckles [onlinejudge]
random☆☆☆☆Aerobics [codejam]
range minimum query☆☆Tetris [tju]
reading☆☆Enormous Input Test [spoj]
rectangle max sum☆☆☆☆Finding Seats [icpcarchive]
rectangles from histogram☆☆Largest Rectangle in a Histogram [tju]
segment tree☆☆☆☆Ultra Quick-Sort [tju]
shortest path variants☆☆Almost the shortest route [tju]
shortest path variants☆☆Heavy Cargo [tju]
simulation☆☆☆☆Bot Trust [codejam]
sorting☆☆☆☆Common Permutation [tju]
sorting☆☆Disk Tree [tju]
sortingEditor Nottobad [onlinejudge]
sorting☆☆I am Lord Voldemort [tju]
sortingWalk [tju]
sorting☆☆☆☆What's Cryptanalysis? [onlinejudge]
stackBinary Trees [tju]
stackInsults [icpcarchive]
string☆☆☆☆Excessive Space Remover [onlinejudge]
stringFile Fragmentation [onlinejudge]
string☆☆☆☆Java vs C++ [tju]
strongly connected components☆☆Capital City [spoj]
structures☆☆A concrete ad_hoc [spoj]
structures☆☆Encryption [spoj]
structures☆☆Havannah [codejam]
structures☆☆Phone List [spoj]
subsetsum☆☆Boat Burglary [tju]
suffix tree☆☆☆☆Stammering Aliens [spoj]
sweepline☆☆☆☆Line Segments [tju]
sweepline☆☆☆☆Rectilinear polygon [tju]
sweepline☆☆Retour vers le futur [prologin]
sweepline☆☆☆☆The Skyline Problem [onlinejudge]
sweepline☆☆☆☆Weird Advertisement [onlinejudge]
topological order☆☆Ordering Tasks [onlinejudge]
topological order☆☆Project File Dependencies [spoj]
topological order☆☆Rare Order [onlinejudge]
traveling salesman☆☆Collecting Beepers [tju]
trie☆☆Spell checker [onlinejudge] [icpcarchive]
two sat☆☆Manhattan [onlinejudge]
two sat☆☆☆☆Seminar Room [tju]
two sat☆☆Soldiers on Parade [spoj]
union disjoint rectangles☆☆City Park [icpcarchive]
union find☆☆☆☆Heavy Transportation [poj] [tju]
union rectangles☆☆☆☆Rectangles [tju]