Problems
Pick a problem and write your solution in the built-in editor. The judge runs it against real test cases while you watch, and the wider archive is open to read whenever you like.
Total results514 problems
| Title | Level | Topics | Solved | Time limit | Memory limit | Judge |
|---|---|---|---|---|---|---|
| SleepwalkerA self-similar walk on a 3^k by 3^k grid is defined by a recursive rewrite; given a starting tile on the walk and a hole tile, find the number of steps until the walk reaches the hole. | Hard9 | RecursionDivide and conquer+2 | No attempts yet | 1s | 128 MB | Judgeable |
| AB-wordsGiven up to 1000 nice ab-words (balanced parentheses words), count the maximum subset of pairwise non-similar words under a recursive similarity relation. | Hard9 | TreeHash map+2 | No attempts yet | 1s | 128 MB | Judgeable |
| Recursive AntOn a 2^n by 2^n board with at most 50 forbidden cells, find for each of the four borders a cell where a recursive quarter-by-quarter Hamiltonian tour can end, or report none. | Hard9 | Divide and conquerRecursion+2 | No attempts yet | 1s | 128 MB | Judgeable |
| Dragon PatternCount how many times pattern S appears as a contiguous block in the length 2^n direction string of the order-n left dragon curve. | Hard9 | String matchingRecursion+2 | No attempts yet | 5s | 128 MB | Judgeable |
| Combinator ExpressionCount the fewest BCKI rewrite steps that reduce the given expression to its normal form. | Hard9 | Dynamic programmingTree+1 | No attempts yet | 1s | 256 MB | Judgeable |
| Laser SensorsGiven N blue points and 2N red points in general position, build the particular non-crossing perfect matching prescribed by the paper's recursive angular-sweep Solve/Attach procedure. | Hard9 | Divide and conquerGeometry+2 | No attempts yet | 2s | 512 MB | Judgeable |
| LegendsGiven a connected graph, decide whether it can be built from one of five small starting graphs using edge additions, isolated-vertex additions, and vertex splits (each split adds a new vertex adjacent to the old one). | Hard9 | GraphDivide and conquer+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Fractal TreeFor a recursively defined fractal tree F_k, answer queries giving the distance between two DFS-labeled vertices. | Hard9 | TreeRecursion+2 | No attempts yet | 7s | 512 MB | Judgeable |
| N and MFind the eventual constant residue modulo M of the power tower N, N^N, N^{N^N}, ... given N and M up to 1e9. | Hard9 | MathNumber theory+1 | No attempts yet | 1s | 1024 MB | Judgeable |
| Mischievous JunseokGiven a short English word and a multiset of letters, count the distinct strings obtainable from any contiguous substring with that letter multiset under the recursive half-split-and-reverse rule. | Hard9 | Brute forceRecursion+2 | No attempts yet | 2s | 256 MB | Judgeable |
| Gosu 2Given a tournament on N players, find a transitive subtournament (chain) of size exactly 1 + floor(log2 N). | Hard9 | Divide and conquerCombinatorics+2 | No attempts yet | 2s | 1024 MB | Judgeable |
| Hanging RackGiven a binary hanging rack with 2^n hooks, find the hook number (mod 1e9+7) used on the k-th step when coats are hung to keep every rod balanced within 0 or 1. | Hard9 | MathRecursion+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Regarding How a Simple DFS Problem I Thought Was Problem A Became Problem E in This Contest (Easy)Given a perfect binary tree with N = 2^k - 1 weighted nodes numbered in heap order and an implied axis-aligned layout, find the maximum sum of weights inside any axis-parallel rectangle whose sides don't cross a node. | Hard9 | Divide and conquerDynamic programming+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Bitwise XorCount non-empty subsequences in which the pairwise xor of every two chosen elements is at least x, modulo 998244353. | Hard9 | Bit manipulationTrie+2 | No attempts yet | 2s | 512 MB | Judgeable |