Problems

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Total results29,137 problems

Tarot Sham Boast
Hard9
String matching, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shifty Grid
Hard9
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rolling the Bottle
Hard9
Geometry, Sorting+2
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Largest window sum
Hard9
Greedy, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Minimum Cycle Mean
Hard9
Dynamic programming, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pseudoknot
Hard9
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Creating Fake News
Hard9
Math, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fashion Show
Hard9
Greedy, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Slate Modern (Large)
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
80s
Memory limit
512 MB
Judgeable
Omnicircumnavigation (Large)
Hard9
Geometry, Math+2
No attempts yet
Time limit
120s
Memory limit
512 MB
Judgeable
Stack Management (Small)
Hard9
Game theory, Simulation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Sequence and Transformation
Hard9
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Expected value of the greatest common divisor
Hard9
Probability, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Polynomial and Queries
Hard9
Number theory, Divide and conquer+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
NPM998244353 (Hard)
Hard9
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Counting multiples with a bounded digit sum
Hard9
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Smallest unreachable subsequence sum
Hard9
Segment tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Good triples of paths
Hard9
Combinatorics, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Strongly Matchable
Hard9
Graph, Math+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Equivalent Deformation
Hard9
Geometry, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Leapfrog
Hard9
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fractal Tree
Hard9
Tree, Recursion+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Arranging tiles
Hard9
Dynamic programming, Geometry+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Craters
Hard9
Geometry, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Enlarging Enthusiasm
Hard9
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Treasure Map
Hard9
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jupiter Rock Paper Scissors
Hard9
Game theory, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Intuidiff
Hard9
String matching, Greedy+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Crazy Rotations
Hard9
String matching, Combinatorics+2
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
GCD Sum
Hard9
Number theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Skiing
Hard9
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Restaurant Bribes
Hard9
Graph, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
One-Way Streets
Hard9
Graph, DFS+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Intrinsic Interval
Hard9
Segment tree, Stack+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Lunar Landscape
Hard9
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Journey from Petersburg to Moscow
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Laminar Family
Hard9
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Toys
Hard9
Combinatorics, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Workbook Algorithms
Hard9
Combinatorics, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Secret Agent
Hard9
Graph, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Garage
Hard9
Segment tree, Number theory+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Counting Cycles
Hard9
Graph, DFS+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Leaders
Hard9
Game theory, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Disco Dance Debacle
Hard9
Graph, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Imelda's Shopping Spree
Hard9
Segment tree, Array+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Majestic Gourmet University
Hard9
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kabobs
Hard9
Dynamic programming, String+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Vera and Love Triangles
Hard9
Combinatorics, Number theory+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Drama
Hard9
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Push a Box
Hard9
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
L-th K-th number
Hard9
Binary search, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gardener
Hard9
Segment tree, Binary search+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Revenge of the Broken Door
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Revenge of the Endless BFS
Hard9
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Conveyor Belt
Hard9
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pipe Fitter and the Fierce Dogs
Hard9
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Blocks 2
Hard9
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stamp Painting
Hard9
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Euclidean Nim
Hard9
Game theory, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maximal polygon brightness
Hard9
Geometry, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Street Trees
Hard9
Union-find, Graph+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
In honor of Taekhee's graduation
Hard9
Math, Simulation+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Want to solve a problem?
Hard9
String matching, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Number of Sequences
Hard9
Bit manipulation, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Uncrossed Knight's Tour
Hard9
Greedy, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tteokpire
Hard9
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
General graph matching
Hard9
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Weight Matching in a General Graph
Hard9
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Home
Hard9
Segment tree, Binary search+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Circle Selection
Hard9
Geometry, Sorting+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
United States of Eurasia
Hard9
Binary search, Dynamic programming+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Voronoi Diagram
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Xtreme NP-hard Problem?!
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Cryptarithm?!
Hard9
Backtracking, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Koala Game
Hard9
Game theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Travelling Merchant
Hard9
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree Escape
Hard9
Game theory, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Growing Trees
Hard9
Tree, Greedy+2
No attempts yet
Time limit
5s
Memory limit
768 MB
Judgeable
The Sprawl
Hard9
Graph, BFS+2
No attempts yet
Time limit
5s
Memory limit
768 MB
Judgeable
Pia's Atelier: The Alchemist of Mysterious Life
Hard9
Union-find, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Booster
Hard9
Graph, Union-find+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
International Cow Lineup Photo Contest
Hard9
Segment tree, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Team Building
Hard9
Union-find, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flipping
Hard9
Graph, Union-find+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Cloud computing
Hard9
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fibonacci representations
Hard9
Segment tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Buildings
Hard9
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Banner
Hard9
String, Dynamic programming+1
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Growing Microorganisms
Hard9
Math, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Game Theory
Hard9
Game theory, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Constellation
Hard9
Math, Geometry+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
N and M
Hard9
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Octoppang Country
Hard9
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
My Lion Paintings
Hard9
Tree, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
LISA
Hard9
Trie, String+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Satellites
Hard9
Geometry, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
To Play or not to Play
Hard9
Intervals, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Black Chain
Hard9
Greedy, Combinatorics+2
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
Matching
Hard9
Geometry, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
In Case of an Invasion, Please. . .
Hard9
Binary search, BFS+2
No attempts yet
Time limit
3.5s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Tarot Sham BoastGiven up to 10 equal-length strings over {R,P,S} and a length n random string, sort the strings by the probability each occurs as a contiguous block.	Hard9	String matchingProbability+2	No attempts yet	2s	512 MB	Judgeable
Shifty GridApply a fixed two-phase procedure of cyclic row and column shifts to sort a permutation grid into row-major order, following the exact TURN steps given.	Hard9	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Rolling the BottleGiven a convex polygon as a bottle base and a water volume, find the minimum and maximum number of sides of the water region as the bottle rolls.	Hard9	GeometrySorting+2	No attempts yet	2.5s	512 MB	Judgeable
Largest window sumFor every window length K, find the largest possible sum of a length-K window over all non-negative arrays that satisfy each given length bound.	Hard9	GreedyPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Minimum Cycle MeanGiven a weighted simple digraph, find the minimum mean weight over all simple directed cycles, or 0 0 if no cycle exists, and output it as a reduced fraction.	Hard9	Dynamic programmingGraph+2	No attempts yet	2s	512 MB	Judgeable
PseudoknotFind the largest t such that the string splits into u v z^R u^R y z with \|u\|>=t and \|z\|>=t, or report -1 if no such split exists.	Hard9	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Creating Fake NewsFind one story vector satisfying n linear equations, then the minimum number of starting people whose reach covers all n people.	Hard9	MathGraph+1	No attempts yet	2s	512 MB	Judgeable
Fashion ShowPlace models on an N by N grid (or upgrade existing ones) so every shared row or column has a plus and every shared diagonal has an x, maximizing style points.	Hard9	GreedyGraph+2	No attempts yet	5s	512 MB	Judgeable
Slate Modern (Large)Fill a huge R by C grid with positive integers so adjacent cells differ by at most D, matching N fixed cells, maximizing the total sum or reporting impossibility.	Hard9	GraphShortest path+2	No attempts yet	80s	512 MB	Judgeable
Omnicircumnavigation (Large)Given points on a unit sphere joined in order by shortest arcs, decide whether the closed path meets every great circle.	Hard9	GeometryMath+2	No attempts yet	120s	512 MB	Judgeable
Stack Management (Small)Decide whether a solitaire game on 2 to 4 short stacks of cards can be reduced to at most one card per stack using two allowed moves.	Hard9	Game theorySimulation+2	No attempts yet	5s	512 MB	Judgeable
Sequence and TransformationCount length-n sequences with entries in [1,m] whose image after applying a min-based affine transformation k times has the given max-minus-min value.	Hard9	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Expected value of the greatest common divisorEach of K values is chosen uniformly from its own interval; find the expected gcd of the K chosen numbers as a fraction mod 1e9+7.	Hard9	ProbabilityMath+2	No attempts yet	2s	512 MB	Judgeable
Polynomial and QueriesEvaluate a degree-N polynomial with integer coefficients at K given points, all modulo the prime 786433, with N and K up to 250000.	Hard9	Number theoryDivide and conquer+2	No attempts yet	10s	512 MB	Judgeable
NPM998244353 (Hard)For every digit-sum cap from 0 to MM, count length-N digit strings divisible by P, modulo 998244353.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Counting multiples with a bounded digit sumCount length-N digit strings divisible by P with digit sum at most M, for every M up to the limit, modulo 998244353.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Smallest unreachable subsequence sumFor each subarray, find the smallest non-negative integer that no subsequence sums to.	Hard9	Segment treeGreedy+1	No attempts yet	2s	512 MB	Judgeable
Good triples of pathsCount triples of simple paths in a tree that are either node-disjoint or pairwise intersecting, modulo 1e9+7.	Hard9	CombinatoricsTree+2	No attempts yet	2s	512 MB	Judgeable
Strongly MatchableDecide whether an even-order graph admits a perfect bipartite matching for every balanced partition of its vertices.	Hard9	GraphMath+2	No attempts yet	3s	512 MB	Judgeable
Equivalent DeformationGiven two equal-area triangles, find the minimum number of vertex-sliding operations that map the first exactly onto the second.	Hard9	GeometryImplementation+2	No attempts yet	2s	512 MB	Judgeable
LeapfrogGiven up to 40 frogs, each starting at x_i with prime jump d_i, find the smallest position where the number of frogs that land there is largest.	Hard9	Number theoryMath+1	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
Arranging tilesGiven up to 14 convex tiles of equal height with cut corners, find the ordering and horizontal placement that minimizes the total frame width when packed side by side.	Hard9	Dynamic programmingGeometry+2	No attempts yet	1s	1024 MB	Judgeable
CratersFind the shortest single closed fence that surrounds all circles at distance 10 or more, given each crater's center and radius.	Hard9	GeometryDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Enlarging EnthusiasmCount the distinct final rankings achievable when positive point bonuses summing to x are announced in increasing order, with the lead changing hands each time.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Treasure MapOn a weighted undirected graph, gold decays each day at every mine; starting at mine 1 with forced moves, maximize total gold collected before stopping.	Hard9	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Jupiter Rock Paper ScissorsEach player crops a length-k substring, Alice morphs one block, then the play phase awards 2/1/1 points by who reaches m round wins first; report the optimal outcome.	Hard9	Game theoryImplementation+2	No attempts yet	2s	512 MB	Judgeable
IntuidiffFind the minimum number of blocks, each a substring of the first string or a single new character, whose concatenation equals the second string.	Hard9	String matchingGreedy+2	No attempts yet	7s	512 MB	Judgeable
Crazy RotationsGiven a row of coloured lights, find the smallest rotation amount that can appear at position p in a non-decreasing sequence of rotation craziness values.	Hard9	String matchingCombinatorics+2	No attempts yet	15s	512 MB	Judgeable
GCD SumFor each k from 1 to n, split a multiset of n numbers into k nonempty groups to maximize the sum of the groups' gcds. n is up to 500000 and each value up to 10^12.	Hard9	Number theoryGreedy+2	No attempts yet	2s	1024 MB	Judgeable
SkiingFind the shortest polygonal path from S down to F that crosses n horizontal gates in top-to-bottom order, and output its breakpoints.	Hard9	GeometryGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Restaurant BribesGiven a friendship graph and a list of k people to bribe, choose a real bribe for each so the total restaurant revenue minus bribe money is maximized, and print the answer as an exact reduced fraction.	Hard9	GraphMath+2	No attempts yet	2s	512 MB	Judgeable
One-Way StreetsGiven an undirected multigraph and required reachable pairs, decide for each edge whether every valid orientation matches the input direction (R), the reverse (L), or both are possible (B).	Hard9	GraphDFS+2	No attempts yet	3s	256 MB	Judgeable
Intrinsic IntervalFor each query range in a permutation, find the smallest subarray containing it whose values form a set of consecutive integers.	Hard9	Segment treeStack+1	No attempts yet	3s	512 MB	Judgeable
Lunar LandscapeCompute the total area covered by axis-aligned squares and 45-degree rotated squares, counting overlaps once.	Hard9	GeometrySorting+1	No attempts yet	2s	512 MB	Judgeable
Journey from Petersburg to MoscowFind the minimum cost path from city 1 to city n where only the k most expensive edges of the path are paid for, or all edges if the path has k or fewer.	Hard9	GraphShortest path+2	No attempts yet	3s	512 MB	Judgeable
Laminar FamilyGiven an undirected tree and f vertex sets, each a simple path, decide whether the family of paths is laminar.	Hard9	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
ToysCount the number of distinct toys formed by strings joining n evenly spaced clamps on one disc to m on another, where rotating each disc independently gives the same toy, modulo 1,000,000,007.	Hard9	CombinatoricsNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Workbook AlgorithmsCount the number of undirected graphs X on N vertices whose number of permutations P satisfying G(P)=X lies between l and r, modulo 1e9+7.	Hard9	CombinatoricsGraph+2	No attempts yet	1s	512 MB	Judgeable
Secret AgentGiven a planar straight-line graph (castle walls) where crossing a wall costs its height, find the minimum cost to travel between successive query points, starting from infinity.	Hard9	GraphGeometry+2	No attempts yet	2s	512 MB	Judgeable
GarageMaintain a sequence under point updates, and for each range query count subarrays whose elements share a common divisor greater than 1.	Hard9	Segment treeNumber theory+2	No attempts yet	4s	256 MB	Judgeable
Counting CyclesA connected undirected graph with n vertices and at most n+15 edges is given; count all simple cycles, where a simple cycle is a connected subgraph with every degree exactly two.	Hard9	GraphDFS+2	No attempts yet	4s	512 MB	Judgeable
LeadersAnimals in a circle alternately raise a running number by 1 to K; whoever is forced to say M loses, and we find the winner of every start position.	Hard9	Game theoryDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Disco Dance DebacleGiven a grid where some cells are unlit (unions of rectangles), find the fewest cell states to flip so that a set of alternating row-column dances can cover all lit cells, each dance starting and ending on the same cell with different first and last feet.	Hard9	GraphGreedy+2	No attempts yet	5s	512 MB	Judgeable
Imelda's Shopping SpreeMaintain a sequence of prices under range-add and range-reverse, and after each update output the number of contiguous segments whose values are strictly increasing.	Hard9	Segment treeArray+2	No attempts yet	5s	512 MB	Judgeable
Majestic Gourmet UniversityGiven proposed FC and IC lab slots with teacher conflicts, seat limits, and timing rules, choose a valid set of labs using the fewest distinct starting days.	Hard9	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
KabobsCount length-K strings over the given alphabet that satisfy all substring-implication rules of the form b>e, modulo 10^7.	Hard9	Dynamic programmingString+2	No attempts yet	5s	512 MB	Judgeable
Vera and Love TrianglesFor each pair of friends, a crush direction is set by the parity of the bit-count of a modular power expression; count cyclic triples.	Hard9	CombinatoricsNumber theory+2	No attempts yet	2s	256 MB	Judgeable
DramaCount the number of valid pyramid colourings of an H by N grid with exactly N black cells, modulo 10^9+7.	Hard9	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Push a BoxGiven a grid with Bessie and a pushable box, decide for each queried cell whether the box can reach it.	Hard9	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
L-th K-th numberGiven N cards, take the K-th smallest value of every contiguous block of length at least K, then report the L-th smallest of all those values.	Hard9	Binary searchArray+2	No attempts yet	2s	512 MB	Judgeable
GardenerMaintain N gardens under plantings, range deletions of plants taller than h, and range count queries, all with time-dependent growth.	Hard9	Segment treeBinary search+2	No attempts yet	3s	128 MB	Judgeable
Revenge of the Broken DoorAn adversary hides one edge under construction; the traveler learns about an edge only upon reaching its endpoint and must minimize the worst-case distance from S to T.	Hard9	GraphShortest path+2	No attempts yet	10s	512 MB	Judgeable
Revenge of the Endless BFSDecide whether a buggy BFS that forgets visited vertices ever terminates on a given directed graph, and if so output the loop count modulo 1e9+7.	Hard9	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Conveyor BeltAfter each of Q delivery requests (a, b, p) is added, report the minimum time to finish all tasks, given plates arrive one per second and each plate carries one product.	Hard9	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Pipe Fitter and the Fierce DogsIn a grid where every odd row and column holds a house, cover all houses with downhill chains, minimizing the cost of pipes through dog blocks, using at most K chains.	Hard9	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Blocks 2Count the ways to tile an N x M rectangle with rotated k x N blocks (k=1..N), modulo 1999, where M can be as large as 10^10.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Stamp PaintingCount the distinct colorings of an N-unit canvas obtainable by stamping K-wide colored stamps so every unit ends up painted, modulo 1e9+7.	Hard9	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Euclidean NimFor each pair of move sizes p and q and starting pile n, decide which player wins the take-or-add game, or that it draws.	Hard9	Game theoryMath+1	No attempts yet	2s	512 MB	Judgeable
Maximal polygon brightnessGiven a convex polygon and a sequence of vertex deletions, compute after each deletion the largest total length of edges that a single external light point can illuminate.	Hard9	GeometryDynamic programming+2	No attempts yet	3s	1024 MB	Judgeable
Street TreesMaintain a minimum-cost coloring of N vertices with two colors under incremental equality/inequality constraints and point cost updates, reporting the optimum after each operation.	Hard9	Union-findGraph+2	No attempts yet	2s	256 MB	Judgeable
In honor of Taekhee's graduationDeer bounce on a line segment [0,T], each with strength; a statue at x falls when the net force of deer that have reached it exceeds W. Maximize the fall time over x.	Hard9	MathSimulation+2	No attempts yet	3s	128 MB	Judgeable
Want to solve a problem?For given K and C, choose A > 0 to maximize the characters saved by writing K+A repeated K+A times instead of K repeated K times, minus C times A.	Hard9	String matchingMath+2	No attempts yet	1s	128 MB	Judgeable
The Number of SequencesFor a given N and C, find the lexicographically smallest triple (X, Y, Z) such that exactly C ordered N-tuples of 31-bit integers have OR X, AND Y, XOR Z, or report none exists.	Hard9	Bit manipulationCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Uncrossed Knight's TourGiven an m by n board (m at most 8, n up to 1e15), find the maximum number of squares a closed knight tour can visit without crossing itself.	Hard9	GreedyDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
TteokpireCount the number of ways to write N as an ordered sequence of one or more positive integers; equivalently, count compositions of N, modulo 1e9+7, for N up to 1e12.	Hard9	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
General graph matchingGiven an undirected graph with N vertices and M edges, print the size of a maximum matching.	Hard9	GraphGreedy+2	No attempts yet	1s	128 MB	Judgeable
Maximum Weight Matching in a General GraphGiven a weighted undirected graph, find a matching with maximum total edge weight.	Hard9	GraphGreedy+1	No attempts yet	2s	512 MB	Judgeable
New HomeStores of k types each occupy a point and an open year interval; for each (location, year) query, report the maximum over types of the distance to the nearest open store of that type, or -1 if some type is missing.	Hard9	Segment treeBinary search+2	No attempts yet	5s	1024 MB	Judgeable
Circle SelectionProcess circles in decreasing radius order; each chosen circle removes all remaining circles that intersect it, and for every circle you must report which chosen circle eliminated it.	Hard9	GeometrySorting+2	No attempts yet	3s	1024 MB	Judgeable
United States of EurasiaSplit N points sorted by x into at most K contiguous groups, minimizing the largest squared diameter within any group.	Hard9	Binary searchDynamic programming+2	No attempts yet	20s	1024 MB	Judgeable
Voronoi DiagramGiven a connected weighted graph and a set of source vertices, assign every point on every edge to its nearest source (smallest index on ties) and report the total length each source owns.	Hard9	GraphShortest path+2	No attempts yet	2s	1024 MB	Judgeable
Xtreme NP-hard Problem?!Find the minimum-weight simple path from vertex 1 to vertex n that uses exactly k edges, or report -1; with n, m, k up to 10^6 this is explicitly NP-hard.	Hard9	GraphShortest path+2	No attempts yet	5s	1024 MB	Judgeable
Cryptarithm?!Given three letter strings A+B=C, decide whether some assignment of distinct digits to letters makes the addition valid, columns up to 18 long.	Hard9	BacktrackingMath+2	No attempts yet	1s	128 MB	Judgeable
Koala GameDetermine properties of a hidden permutation by bidding stones in a game where Koala optimally maximizes the sum of values she wins, using as few rounds as possible.	Hard9	Game theoryGreedy+2	No attempts yet	2s	512 MB	Judgeable
Travelling MerchantGiven a directed weighted graph and per-market buy/sell prices for K items, find the maximum profit-to-duration ratio of a closed walk trading at most one item at a time, floor it.	Hard9	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Tree EscapeOn a rooted tree where each leaf starts with one piece, players alternately move a piece to its parent and remove it at the root; decide if the first player wins.	Hard9	Game theoryTree+2	No attempts yet	2s	512 MB	Judgeable
Growing TreesGiven a tree whose edge weights change linearly with the day, find the day in [0, D] that minimizes the diameter, and report that diameter.	Hard9	TreeGreedy+2	No attempts yet	5s	768 MB	Judgeable
The SprawlOn an infinite grid, N cities grow one cell per day in index order; sum over all pairs the first day the two cities' territories touch and connect.	Hard9	GraphBFS+2	No attempts yet	5s	768 MB	Judgeable
Pia's Atelier: The Alchemist of Mysterious LifeGiven 2x2 parity constraints on an n by n binary grid, decide for each day whether a grid exists satisfying all interval cell-fixing conditions active that day.	Hard9	Union-findPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
BoosterFor each query, decide whether the character can travel from checkpoint A to checkpoint B with maximum HP X, given walking drains HP and the booster moves only along axes.	Hard9	GraphUnion-find+2	No attempts yet	8s	512 MB	Judgeable
International Cow Lineup Photo ContestGiven a 0/1 array and up to 1e5 adjacent swaps, after each swap report the longest subarray with equal numbers of 0s and 1s.	Hard9	Segment treePrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Team BuildingMaintain teams under merge, a split that separates members by their remainder mod P, and size queries, for up to 100000 commands.	Hard9	Union-findImplementation+1	No attempts yet	1s	512 MB	Judgeable
FlippingCount initial black/white colorings of an N by M grid that can reach the given coloring when a press inverts the whole monochromatic connected component containing that cell, modulo 1e9+7.	Hard9	GraphUnion-find+2	No attempts yet	5s	256 MB	Judgeable
Cloud computingChoose a set of orders and a set of computers to buy so every accepted order gets enough cores at its minimum clock rate, maximizing payments minus computer costs.	Hard9	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Fibonacci representationsGiven a sequence a, report after each prefix the number of ways to write the sum of F_{a_i} as distinct Fibonacci numbers, modulo 1e9+7.	Hard9	Segment treeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
BuildingsCount the distinct houses formed by placing m walls of n by n colored squares around an m-gon, up to rotation, modulo 1e9+7.	Hard9	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
BannerCount the orders of the 26 machines that let greedy longest-substring sewing finish a string of up to 35 letters in the fewest hours, modulo four primes.	Hard9	StringDynamic programming+1	No attempts yet	6s	512 MB	Judgeable
Growing MicroorganismsWith buy costs and production costs, buy microorganisms and make each kind produce others to reach x_i of every kind at minimum total cost.	Hard9	MathGreedy+2	No attempts yet	2s	512 MB	Judgeable
Game TheoryTwo players alternately remove stones from a vertex of a connected graph, then move along an edge or stay put; output who wins with optimal play from start vertex s.	Hard9	Game theoryGraph+1	No attempts yet	1s	256 MB	Judgeable
ConstellationChoose a subset of up to 2e5 points maximizing total brightness so that from any chosen point all others fall in the first or third quadrant, with the nearest point in each occupied quadrant within Chebyshev distance L.	Hard9	MathGeometry+2	No attempts yet	1.5s	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
Octoppang CountryGiven a connected unweighted graph with K infected vertices and threshold T, compute for every vertex the number of uninfected vertices left when it is deleted and each component with at least T infected vertices spreads infection fully.	Hard9	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
My Lion PaintingsFor each room as the work room, find the maximum number of paintings you can repair within time M, where each repair costs C_i plus its distance to that room.	Hard9	TreeDynamic programming+1	No attempts yet	3s	1024 MB	Judgeable
LISAGiven n strings and range queries, count distinct concatenations of a non-empty prefix of one string in the range with a non-empty suffix of another string in the range.	Hard9	TrieString+2	No attempts yet	3s	512 MB	Judgeable
SatellitesSatellites appear and disappear above a half-disc planet; for each query decide whether two satellites have a common coverage point outside the planet that no other live satellite covers.	Hard9	GeometryDynamic programming+2	No attempts yet	4s	512 MB	Judgeable
To Play or not to PlayGiven Vasya's and Petya's play intervals and a boost threshold C, find the maximum final experience Vasya can reach when they schedule their play optimally.	Hard9	IntervalsDynamic programming+1	No attempts yet	4s	512 MB	Judgeable
Black ChainGiven a chain of n rings (up to 10^18), find the fewest rings to open so the resulting pieces can be combined into every weight from 1 to n.	Hard9	GreedyCombinatorics+2	No attempts yet	0.1s	512 MB	Judgeable
MatchingGiven point sets A and B, find a translation of B that minimizes the width of the smallest strip containing both sets, and print that width.	Hard9	GeometryMath	No attempts yet	1s	512 MB	Judgeable
In Case of an Invasion, Please. . .Place people from n city nodes, with at most 10 capacity-limited shelters on a weighted road network, to minimize the latest arrival time at any shelter.	Hard9	Binary searchBFS+2	No attempts yet	3.5s	512 MB	Judgeable