Problems

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Total results29,413 problems

Far, Far Away
Hard8
Binary search, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Interesting World of Arrays
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Knights and Dragons
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Adding Parentheses
Hard8
Dynamic programming, Recursion+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Add Parentheses 3
Hard8
Divide and conquer, Dynamic programming+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Fraction Challenge
Hard8
String, Hash map+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Counting Stairs
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Distinct Substrings
Hard8
String matching, Math+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Interactive Array Guessing
Hard8
Implementation, Divide and conquer+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Distance Sum
Hard8
Graph, BFS+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Fractions
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
King Kog's Reception
Hard8
Segment tree, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hiking
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Three Primary Colors
Hard8
Divide and conquer, Segment tree+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Cutting Paper
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
XOR Poker
Hard8
Bit manipulation, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The ABCD Murderer
Hard8
String matching, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Trees Gump
Hard8
Divide and conquer, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Incredible Hull
Hard8
Geometry, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shooter Island
Hard8
Union-find, Intervals+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Erasing Matrix
Hard8
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Katty and Wonki
Hard8
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
The Pied Piper
Hard8
Graph, Simulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Nader Shah
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Python Classes
Hard8
Greedy, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shortest Common Non-Subsequence
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
What Goes Up Must Come Down
Hard8
Divide and conquer, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Colorful Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Metal Bar Cube
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Balance Beam
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sort It Out
Hard8
Sorting, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Amusement Park
Hard8
Graph, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bulldozer
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Illumination
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cats or Dogs
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Trodden Cable
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Fox Observation
Hard8
Geometry, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Spotlight Movement
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gravity Point
Hard8
Geometry, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Identity Function
Hard8
Math, Number theory+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Live Programming
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Endless BFS
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Librarian's Work
Hard8
Greedy, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Permutation Period
Hard8
Math, Number theory+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Santa's Gift
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Prefix Suffix Search
Hard8
String matching, Trie+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Nim without Zero
Hard8
Game theory, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sum of QQ
Hard8
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Clique Coloring
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cellular Automaton
Hard8
Bit manipulation, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Directions
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Distance Sum
Hard8
Tree, Greedy+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Emotional Tetris
Hard8
Segment tree, Simulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cat Dating
Hard8
DFS, Greedy+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Difference
Hard8
Simulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pear-wise Voting
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequential Yahtzee
Hard8
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Funny Number Game
Hard8
Bit manipulation, Math+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Fibonacci Nim
Hard8
Game theory, Math+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Card Game
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Knight Game
Hard8
Game theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum of Vectors
Hard8
Sorting, Geometry+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Prime Power Game
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ainta Game
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Naming the Computer
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XOR MST
Hard8
Trie, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence and Queries 20
Hard8
Trie, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Set and Queries
Hard8
Bit manipulation, Math+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
XOR Submatrix
Hard8
Bit manipulation, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Distinct Substring Queries 2
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Graph and Queries
Hard8
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree and Queries 12
Hard8
Tree, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Substring Replacement
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
K-th Substring
Hard8
String, Trie+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tail Star
Hard8
Number theory, Math
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
String Folding
Hard8
String, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chessboard Tour 1
Hard8
BFS, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of Integer Lattice Points
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Largest Rectangle in a Histogram and Queries
Hard8
Segment tree, Sliding window+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Sequence and Queries 22
Hard8
Segment tree, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maaaaaaaaaze
Hard8
Brute force, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maximum Subarray Sum and Queries
Hard8
Segment tree, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rope and Queries
Hard8
Linked list, Implementation+2
No attempts yet
Time limit
0.3s
Memory limit
512 MB
Judgeable
Piece of Cake
Hard8
Combinatorics, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
It's a Mod, Mod, Mod, Mod World
Hard8
Math, Number theory+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Monotony
Hard8
Matrix, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Heaps of Fun
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Intersecting Rectangles
Hard8
Sorting, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting Strings
Hard8
String, Greedy+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Knight of the Tarot Cards
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Planes, Trains, but not Automobiles
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
3-SAT 2
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Redistricting
Hard8
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shortcut
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow Dating
Hard8
Math, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow Land
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Painting the Barn (Gold)
Hard8
Prefix sum, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kisik
Hard8
Sorting, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Transport
Hard8
Divide and conquer, Tree+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Symphony
Hard8
Sorting, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Far, Far AwayGiven an n by n cost matrix and budget m, find the maximum number of edges on a walk from vertex 1 with total cost at most m; vertices and edges may repeat.	Hard8	Binary searchGraph+2	No attempts yet	2s	512 MB	Judgeable
Interesting World of ArraysCount arrays of length n whose values each satisfy a[i] = count(i) mod m, for n up to 12 and m up to 1e9.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Knights and DragonsGiven n distinct points (strength, magic), decide for each whether it lies in the convex hull of the others, since a point is reachable by repeated weighted averaging of the other points exactly when it is not a vertex of the hull.	Hard8	GeometrySorting+2	No attempts yet	4s	512 MB	Judgeable
Adding ParenthesesParenthesize a single-digit expression with non-nested single-operator parentheses to maximize its left-to-right value.	Hard8	Dynamic programmingRecursion+2	No attempts yet	0.5s	512 MB	Judgeable
Add Parentheses 3Parenthesize an alternating digit and +,-,* expression of length up to 19 to maximize its value, respecting left-to-right and multiplication-first rules.	Hard8	Divide and conquerDynamic programming+2	No attempts yet	1.5s	512 MB	Judgeable
Fraction ChallengeMultiply many huge fractions given as digit strings and output the reduced product as a/b.	Hard8	StringHash map+2	No attempts yet	0.5s	512 MB	Judgeable
Counting StairsCount symmetric stairs (partitions of n into distinct parts) with n cubes, modulo 998244353, for up to 1e4 queries with n up to 2e5.	Hard8	Dynamic programmingMath+2	No attempts yet	3s	512 MB	Judgeable
Distinct SubstringsGiven a period string p and length n, count distinct substrings of the string formed by repeating p and cutting to n. n may be 1e9.	Hard8	String matchingMath+1	No attempts yet	3s	512 MB	Judgeable
Interactive Array GuessingGiven n hidden arrays of up to 10 distinct values each, find all arrays using queries that return concatenated contents of chosen arrays, without delimiters.	Hard8	ImplementationDivide and conquer+1	No attempts yet	3s	512 MB	Judgeable
Distance SumGiven a connected undirected unweighted graph with at most n+42 edges, compute the sum of shortest-path distances over all unordered vertex pairs.	Hard8	GraphBFS+2	No attempts yet	4s	512 MB	Judgeable
FractionsGiven n, represent 1 - 1/n as a sum of fractions with denominators dividing n and strictly between 1 and n, or report that no such sum exists.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
King Kog's ReceptionKnights join or cancel reservations with a start time and duration; after each change, a query asks how long a visitor arriving at time t must wait, since she yields to a knight arriving at the same instant.	Hard8	Segment treeBinary search+2	No attempts yet	2s	512 MB	Judgeable
HikingPick a non-end point as the goal, walk uphill from node 1 to it and downhill to node N, and maximize h*E minus D times total distance or report that no route exists.	Hard8	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
Three Primary ColorsGiven up to 25,000 colored rectangles painted one at a time without repainting already covered pixels, report the total area of each of the seven resulting color regions.	Hard8	Divide and conquerSegment tree+2	No attempts yet	3s	256 MB	Judgeable
Cutting PaperGiven a simple polygon, count how many pieces of paper lie inside and outside it after cutting along the full extended lines of every edge.	Hard8	GeometryImplementation+1	No attempts yet	3s	128 MB	Judgeable
XOR PokerGiven N integers, choose a nonempty subset of even size whose XOR is maximum and print that value.	Hard8	Bit manipulationGreedy+1	No attempts yet	2s	512 MB	Judgeable
The ABCD MurdererFind the fewest word occurrences needed to cover a target text exactly when cut-outs may overlap on matching text, or report -1 if impossible.	Hard8	String matchingArray+2	No attempts yet	2s	512 MB	Judgeable
Trees GumpPlace the N units of a given tree onto the N points so that the tree's edges, drawn as straight segments, never cross.	Hard8	Divide and conquerGeometry+2	No attempts yet	2s	512 MB	Judgeable
Incredible HullGiven N points sorted by profit, with the outer points forming a convex perimeter, the task is to find the size of a largest clique, how many largest cliques exist, and how many points belong to one.	Hard8	GeometryGraph+1	No attempts yet	1s	512 MB	Judgeable
Shooter IslandOn a 50 by 100000 grid, rectangles flood when hit, and after each query decide whether a radius-0.31416 boat can sail between two given squares on the remaining water.	Hard8	Union-findIntervals+2	No attempts yet	3s	512 MB	Judgeable
Erasing MatrixDecide whether all cells of a grid can be driven to zero by repeatedly adding the same integer k to two adjacent cells while keeping every value non-negative, and print a valid sequence of at most 10^6 operations.	Hard8	GraphGreedy+2	No attempts yet	1s	256 MB	Judgeable
Katty and WonkiAdd 2 edges to an N-vertex tree to maximize vertices lying on created cycles; return that maximum for the worst case for the tree owner.	Hard8	TreeGraph+2	No attempts yet	1s	256 MB	Judgeable
The Pied PiperPlace the fewest cells so every frozen walk under the U/D/L/R map enters a safe cell; model directed functional reverse graphs and find a minimum set of path-starting states.	Hard8	GraphSimulation+2	No attempts yet	1s	256 MB	Judgeable
Nader ShahFrom roads and marked Afshari edges, reconstruct the root and capture order consistent with the growth rule, lexicographically minimum, or output Wrong Map!.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Python ClassesReorder single-inheritance class definitions so every superclass appears before its subclasses, using the fewest cut-and-paste moves, or output -1 when superclass links form a cycle.	Hard8	GreedyUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Shortest Common Non-SubsequenceGiven two binary strings of length up to 4000, find the shortest binary string that is a subsequence of neither, breaking ties by lexicographic order.	Hard8	Dynamic programmingGreedy+2	No attempts yet	5s	512 MB	Judgeable
What Goes Up Must Come DownRearrange the cards by adjacent swaps into a bitonic order with the fewest moves, counting inversions by value.	Hard8	Divide and conquerSorting+2	No attempts yet	2s	512 MB	Judgeable
Colorful TreeMaintain vertex colors on a tree under point updates and answer queries giving the number of edges in the minimal subtree spanning all vertices of one color.	Hard8	TreeDFS+2	No attempts yet	5s	512 MB	Judgeable
Metal Bar CubeGiven the four viewing counts from left, right, top and bottom of an N by N grid, decide whether any placement of blocked cells can produce exactly those counts.	Hard8	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
Balance BeamChoose at each beam position a cash value or a fair coin random walk stopped at the ends, maximizing expected payment for every starting position.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
Sort It OutFind the smallest subset of cow IDs S such that repeatedly yelling at each ID in S in increasing order eventually sorts the permutation, then output the K-th lexicographically smallest such subset.	Hard8	SortingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Amusement ParkGiven a connected graph, write 0 or 1 on each vertex so a walker starting anywhere can recover a 60-bit X in as few moves as possible.	Hard8	GraphBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
BulldozerChoose two parallel lines and take every weighted point between them, maximizing the sum of gold values minus rock costs.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
IlluminationChoose a subset of trees to decorate, maximizing total beauty, so that for each of M given intervals at most one tree inside it is chosen.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
Cats or DogsGiven a tree where cats, dogs, and empty huts change over Q days, find the fewest paths to block so no cat and dog can reach each other.	Hard8	TreeDynamic programming+1	No attempts yet	3s	512 MB	Judgeable
Trodden CablePlace a cable along grid edges connecting two given corners so that, over repeated fixed walks, staff cross it as few times as possible.	Hard8	Shortest pathGraph+2	No attempts yet	5s	512 MB	Judgeable
Fox ObservationGiven weighted lattice points, find the two-corner rectangle that maximizes total enclosed weight divided by its area, printed as a reduced fraction.	Hard8	GeometryDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
Spotlight MovementGiven N spotlights whose centers move around polygonal orbits, decide whether Ciel can walk from a start point to an end point while staying inside at least one illuminated circle at all times.	Hard8	GeometrySimulation+2	No attempts yet	2s	512 MB	Judgeable
Gravity PointA random mass for tiles A and B is drawn from given ranges; find the chance the grid's center of gravity falls in a filled cell.	Hard8	GeometryProbability+2	No attempts yet	2s	512 MB	Judgeable
Identity FunctionGiven N, find the smallest positive k with every iterate F_k(a)=a for 1<=a<N under f(a)=a^N mod N, or output -1.	Hard8	MathNumber theory+1	No attempts yet	5s	512 MB	Judgeable
Live ProgrammingChoose a subset of songs within total length T and order them to maximize the sum of basic points minus squared feature differences between consecutive songs.	Hard8	Dynamic programmingSorting+2	No attempts yet	5s	512 MB	Judgeable
Endless BFSRun a BFS that forgets visited vertices, so the active set alternates between bipartition classes. Decide whether it ever equals all vertices and report the least step when it does.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Librarian's WorkGiven a shuffled permutation with book weights, restore the original order using two adjacent-rotation-like moves and minimize total labor cost.	Hard8	GreedyDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Permutation PeriodStarting from the identity permutation, apply swaps one at a time and after each swap report the permutation's period modulo 1e9+7, where the period is the LCM of its cycle lengths.	Hard8	MathNumber theory+2	No attempts yet	5s	512 MB	Judgeable
Santa's GiftFor each family size k from 1 to M, choose a subset of gift kinds so k copies of each fit in capacity C, maximizing total price.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Prefix Suffix SearchGiven N words and Q prefix/suffix pairs, report for each query how many words match both prefix and suffix. Total input length is up to 2.5 million.	Hard8	String matchingTrie+2	No attempts yet	3s	512 MB	Judgeable
Nim without ZeroAn impartial game where a move loses if it makes the XOR of all heap sizes equal zero. Decide the winner with optimal play.	Hard8	Game theoryBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Sum of QQCount axis-parallel rectangles in the multiplication table whose entries sum to exactly S, with S up to 100000.	Hard8	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Clique ColoringGiven up to five clique sizes, find the smallest number of vertices in a complete graph whose edges can be covered by cliques of those sizes with no repeated edge.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Cellular AutomatonGiven w and a binary string s of length 2^(2w+1), find the lexicographically smallest rule string p that is at least s and keeps the count of 1s constant for every initial state.	Hard8	Bit manipulationBacktracking+1	No attempts yet	1s	512 MB	Judgeable
DirectionsPick the cheapest set of direction vectors whose nonnegative multiples let Snuke reach any point from any other, or print -1 if no set works.	Hard8	GeometrySorting+1	No attempts yet	4s	512 MB	Judgeable
Distance SumFor each k, find the minimum total distance from one city to cities 1 through k in a rooted weighted tree where city 1 is the root.	Hard8	TreeGreedy+1	No attempts yet	4s	512 MB	Judgeable
Emotional TetrisGiven Q drops of horizontal 1x4 or vertical 4x1 blocks on a grid, count for each drop how many blocks directly or indirectly rest under it through shared faces.	Hard8	Segment treeSimulation+1	No attempts yet	1s	512 MB	Judgeable
Cat DatingIn a rooted tree, each den holds female cats or male cats with a fall limit; count the maximum number of female-male pairs where a male can reach a female downward within the distance limit.	Hard8	DFSGreedy+2	No attempts yet	4s	1024 MB	Judgeable
DifferenceBuild the sequence from A1 incrementally, adding each next gap so that m hits as a value or an existing difference; report the first step that covers it.	Hard8	SimulationMath+2	No attempts yet	2s	512 MB	Judgeable
Pear-wise VotingGiven ranked ballots and a selectable candidate order, decide for each candidate whether some agenda makes that candidate win sequential pairwise contests.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Sequential YahtzeeGiven up to 195 sequential dice rolls, assign consecutive segments to the 13 Yahtzee categories in order to maximize the total score.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Funny Number GameGiven a 4-digit N and M turns of incrementing one digit with 9 wrapping to 0, decide which player forces the final value above N.	Hard8	Bit manipulationMath+2	No attempts yet	0.5s	512 MB	Judgeable
Fibonacci NimFind which piles lose the Fibonacci-Nim take-away game and decide the winner of the multi-pile sum game with optimal play.	Hard8	Game theoryMath+2	No attempts yet	0.5s	512 MB	Judgeable
Card GameTwo players alternately remove a chosen card and every card with a smaller number; decide the winner under optimal play.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Knight GameTwo players alternately place non-attacking knights on an N x N board; decide who wins under optimal play, with N up to 10,000.	Hard8	Game theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Sum of VectorsChoose two of N vectors, each optionally sign-flipped per coordinate, to minimize the norm of their sum and output the pair with the chosen flips.	Hard8	SortingGeometry+2	No attempts yet	0.5s	512 MB	Judgeable
Prime Power GameTwo players alternately choose a prime power p^k that divides some element and divide every element it divides by p^k; the player who cannot move loses, so print the winner.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Ainta GameGiven K, N, and M, decide who wins a game where a piece moves down, right, or diagonally by K on an N by M board, starting from the top-left corner.	Hard8	Game theoryDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Naming the ComputerGiven a string S and integer K, find the shortest string that contains S as a substring at least K times, and output its length.	Hard8	String matchingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
XOR MSTGiven N labeled vertices where the edge between any two has weight equal to the XOR of their labels, find the total cost of the minimum spanning tree.	Hard8	TrieMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Sequence and Queries 20Maintain a multiset that starts with only 0, supporting insert, delete, and max-XOR queries where every element is XORed with x.	Hard8	TrieBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Set and QueriesAfter each insertion or deletion in a set of up to 500,000 integers, report the maximum XOR achievable by any subset of the current set.	Hard8	Bit manipulationMath+2	No attempts yet	4s	512 MB	Judgeable
XOR SubmatrixBuild the N by M matrix with A[i][j] = V[i] xor U[j] and find the submatrix whose elementwise xor is maximal.	Hard8	Bit manipulationTrie+2	No attempts yet	2s	512 MB	Judgeable
Distinct Substring Queries 2Process a stream of append-character and count-distinct-substrings queries on a growing string, answering each count query online.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Graph and QueriesMaintain an undirected graph under edge insertions and deletions, answering connectivity queries between two vertices after each update.	Hard8	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Tree and Queries 12Maintain a forest under edge insertions and deletions, and answer connectivity queries between two vertices.	Hard8	TreeUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Substring ReplacementReplace each question mark in S with a lowercase letter so that T appears as a substring as many times as possible, and report that maximum count.	Hard8	Dynamic programmingString matching+2	No attempts yet	2s	512 MB	Judgeable
K-th SubstringGiven a string S, answer queries that ask for the K-th distinct substring of S in lexicographic order, or -1 if it does not exist.	Hard8	StringTrie+2	No attempts yet	2s	512 MB	Judgeable
Tail StarGiven prime P and year Q, find the sum of p^Q over all primes p up to P, taken modulo P, since only prime-numbered days have no overtime.	Hard8	Number theoryMath	No attempts yet	5s	256 MB	Judgeable
String FoldingFold the string at a sequence of positions into vertical columns, then find the longest column-run of one repeated character that starts at the bottom with no gaps.	Hard8	StringBrute force+2	No attempts yet	2s	512 MB	Judgeable
Chessboard Tour 1On an N by N board holding distinct numbers, find the fewest seconds (each a single piece move or a piece swap) to travel through squares 1, 2, ..., N^2 in order using a knight, bishop, and rook.	Hard8	BFSShortest path+2	No attempts yet	2s	512 MB	Judgeable
Number of Integer Lattice PointsCount pairs of lattice points in a grid whose connecting segment contains exactly K lattice points.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Largest Rectangle in a Histogram and QueriesGiven a histogram of N bars, each query asks for the height of the width-w rectangle inside bars l to r that has the largest area.	Hard8	Segment treeSliding window+1	No attempts yet	4s	512 MB	Judgeable
Sequence and Queries 22Given a sequence and a stream of updates and range-sum queries, answer each query for the sequence state after its k-th update only, where k can be any earlier prefix of updates.	Hard8	Segment treeDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
MaaaaaaaaazeGiven five 5x5 boards, rotate each freely, stack them in any order, then find the shortest path through the resulting 5x5x5 cube from one corner to the opposite corner.	Hard8	Brute forceBFS+2	No attempts yet	2s	512 MB	Judgeable
Maximum Subarray Sum and QueriesGiven an array, answer queries that ask for the maximum subarray sum inside a given index range.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Rope and QueriesMaintain a string under up to 100,000 queries that cut a substring and move it to the front or back, and print single characters.	Hard8	Linked listImplementation+2	No attempts yet	0.3s	512 MB	Judgeable
Piece of CakeGiven a convex polygon with n vertices in clockwise order, compute the expected area of the convex polygon formed by picking k of the vertices uniformly at random.	Hard8	CombinatoricsGeometry+2	No attempts yet	2s	512 MB	Judgeable
It's a Mod, Mod, Mod, Mod WorldGiven p, q, n, compute the sum of (p*i mod q) for i from 1 to n, for up to 100000 queries with values up to 10^6.	Hard8	MathNumber theory+2	No attempts yet	5s	512 MB	Judgeable
MonotonyCount the subgrids where every row and every column is strictly increasing or strictly decreasing, in a grid of distinct values up to 20 by 20.	Hard8	MatrixDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Heaps of FunGiven a rooted tree where each node i draws a uniform random real in [0, b_i], compute the probability that every parent's value is less than both its children's values, modulo 1e9+7.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Intersecting RectanglesGiven n axis-aligned rectangles with all x and y coordinates distinct, decide whether any two boundaries cross or touch. One rectangle fully containing another does not count.	Hard8	SortingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
Cutting StringsGiven a string s and an integer k, remove at most k non-overlapping substrings to get the lexicographically largest remaining string.	Hard8	StringGreedy+1	No attempts yet	10s	512 MB	Judgeable
Knight of the Tarot CardsFind the minimum total price of tarot cards the knight must buy to reach (0, 0), where each card's values unlock new knight jumps.	Hard8	GraphShortest path+2	No attempts yet	10s	512 MB	Judgeable
Planes, Trains, but not AutomobilesGiven a DAG of one-way train lines and complete flight connectivity, find the minimum number of flights to visit every city once and list all cities whose airport can be used on some optimal route.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
3-SAT 2Given a 3-CNF formula with N variables and M clauses, decide whether it is satisfiable and, if so, output a satisfying assignment.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
RedistrictingGiven a string of H and G representing a line of cows, split it into contiguous districts of length at most K minimizing the number of districts where G outnumbers or ties H.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
ShortcutGiven a weighted undirected graph with cows at each node, add one shortcut edge from node 1 to any other node to maximize the total decrease in shortest-path travel time.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Cow DatingGiven probabilities p_i, choose a contiguous interval maximizing the chance that exactly one bull accepts, and print 10^6 times that probability rounded down.	Hard8	MathTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Cow LandOn a weighted tree, support point value updates and path XOR queries between any two nodes, returning the XOR of enjoyment values along the unique route.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Painting the Barn (Gold)Given N painted axis-aligned rectangles on a 200x200 grid, add up to two disjoint rectangles to maximize the total area covered by exactly K coats.	Hard8	Prefix sumMatrix+2	No attempts yet	2s	512 MB	Judgeable
KisikChoose K of N distinct buildings, arrange them side by side on the ground, and minimize the area of the enclosing bounding rectangle.	Hard8	SortingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
TransportCount ordered city pairs (A, B) in a tree where a truck that fills up at each station along the path can drive from A to B.	Hard8	Divide and conquerTree+1	No attempts yet	1s	512 MB	Judgeable
SymphonyAdd one integer X to every element of A, then change at most K elements to any values, minimizing the sum of absolute differences against B.	Hard8	SortingBinary search+2	No attempts yet	1s	512 MB	Judgeable