Problems

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Total results21,088 problems

Joyful NumbersHard9
Number theory, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Multiple?Hard9
Combinatorics, Number theory +2No attempts yetTime limit6sMemory limit256 MB
Judgeable
Colorful ComponentsHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Brave Seekers of UnicornsHard9
Dynamic programming, Bit manipulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Binary Supersonic UtahraptorsHard9
Game theory, Greedy +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Workers of the World Unite! Just Not Too Close.Hard9
Dynamic programming, Greedy +2No attempts yetTime limit10sMemory limit1024 MB
Judgeable
Derangement RotationsHard9
Combinatorics, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
h-indexHard9
Array, Segment tree +2No attempts yetTime limit2.5sMemory limit512 MB
Judgeable
No Time to DryHard9
Stack, Segment tree +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Stone GameHard9
Game theory, Number theory +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
GamesHard9
Game theory, Combinatorics +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Robot Vacuum 2Hard9
Greedy, Simulation +2No attempts yetTime limit12sMemory limit1024 MB
Judgeable
Graph GameHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Matches Are Not a Toy for ChildrenHard9
Geometry, Hash map +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
PuzzleHard9
Graph, Number theory +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Pearl EmbroideryHard9
Tree, DFS +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Healthy EatingHard9
Dynamic programming, Matrix +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Waging War PeacefullyHard9
Math, Number theory +2No attempts yetTime limit5sMemory limit256 MB
Judgeable
Polynomial and Easy QueriesHard9
Math, Segment tree +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Daily CommuteHard9
Graph, Shortest path +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Boring LessonHard9
Dynamic programming, String +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Road ConstructionHard9
Divide and conquer, Sorting +2No attempts yetTime limit10sMemory limit2048 MB
Judgeable
Navigation 2Hard9
Graph, BFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Vote-Value Disparity 2Hard9
Graph, BFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Vote-Value Disparity 3Hard9
Graph, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Vote-Value Disparity 4Hard9
Graph, DFS +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Vote-Value Disparity 5Hard9
Graph, Divide and conquer +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Binary SubsequencesHard9
Dynamic programming, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Deque GameHard9
Dynamic programming, Combinatorics +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
The GradeHard9
Dynamic programming, Combinatorics +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
FootballHard9
Game theory, Dynamic programming +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
CrossingHard9
Segment tree, Math +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Broken ClocksHard9
Number theory, Math +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Forgotten HomeworkHard9
Matrix, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
TableHard9
Combinatorics, Math +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
TrisolariansHard9
Combinatorics, Dynamic programming +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Jawaian Weapon SetHard9
Number theory, Math +2No attempts yetTime limit3sMemory limit256 MB
Judgeable
ParadeHard9
Geometry, Brute force +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Table 5Hard9
Backtracking, Math +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Table 7Hard9
Backtracking, Brute force +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Gahui and the Read-Write Game 2Hard9
Greedy, Implementation +2No attempts yetTime limit2.5sMemory limit512 MB
Judgeable
TruckHard9
Tree, Dynamic programming +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
TilesHard9
Dynamic programming, Segment tree +2No attempts yetTime limit4sMemory limit1024 MB
Judgeable
Paper, Pen, TriangleHard9
Combinatorics, Math +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Edge First or Vertex FirstHard9
Game theory, Graph +2No attempts yetTime limit8sMemory limit512 MB
Judgeable
Feed candiesHard9
Number theory, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Watching BaseballHard9
Combinatorics, Math +2No attempts yetTime limit8sMemory limit512 MB
Judgeable
Air PollutionHard9
Math, Greedy +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
Do use segment treeHard9
Segment tree, Tree +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Entangled with LotteryHard9
Dynamic programming, Probability +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Tiles are ColorfulHard9
Simulation, DFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Carpenters' LanguageHard9
String, Stack +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Double Magic Made ClearHard9
Graph, Topological sort +2No attempts yetTime limit8sMemory limit512 MB
Judgeable
Webby SubwayHard9
Geometry, Graph +2No attempts yetTime limit8sMemory limit512 MB
Judgeable
Exact ArithmeticHard9
Implementation, Simulation +2No attempts yetTime limit8sMemory limit512 MB
Judgeable
Cut outHard9
Geometry, Math +2No attempts yetTime limit8sMemory limit512 MB
Judgeable
Strange KeyHard9
Graph, Geometry +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Bridge Crossing GameHard9
Graph, Game theory +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Pillar and Wall Defense GameHard9
Geometry, Brute force +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Setting an Exam ProblemHard9
Dynamic programming, Prefix sum +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Slide CircuitsHard9
Graph, Union-find +2No attempts yetTime limitNot setMemory limit1024 MB
Judgeable
Permutation CFGHard9
Recursion, Combinatorics +2No attempts yetTime limit4sMemory limit2048 MB
Judgeable
Sinchon Sequence and QueriesHard9
Segment tree, Dynamic programming +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Sinchon Defense HeadquartersHard9
Geometry, Math +2No attempts yetTime limit1.5sMemory limit1024 MB
Judgeable
Master of String ManipulationHard9
Dynamic programming, Combinatorics +2No attempts yetTime limit2.5sMemory limit1024 MB
Judgeable
CycleHard9
Dynamic programming, Graph +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Binary OperatorHard9
Math, Hash map +2No attempts yetTime limit20sMemory limit1024 MB
Judgeable
RMQHard9
Segment tree, Prefix sum +1No attempts yetTime limit3sMemory limit1024 MB
Judgeable
DiversityHard9
Segment tree, Greedy +1No attempts yetTime limit7sMemory limit512 MB
Judgeable
Calculate! 3Hard9
Tree, Bit manipulation +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Pizzo CollectorsHard9
Number theory, Math +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Tobacco GrowingHard9
Dynamic programming, Combinatorics +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
ScreamersHard9
Graph, Union-find +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
How to Move the BeansHard9
Game theory, Graph +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
Kingdoms and QuarantineHard9
Math, Graph +1No attempts yetTime limit8sMemory limit512 MB
Judgeable
Crab's CannonHard9
String, String matching +1No attempts yetTime limit3sMemory limit512 MB
Judgeable
ElephantsHard9
Graph, MathNo attempts yetTime limit3sMemory limit256 MB
Judgeable
Interval ShuffleHard9
Greedy, Sorting +1No attempts yetTime limit1sMemory limit256 MB
Judgeable
Magic BoxHard9
String matching, String +1No attempts yetTime limit5sMemory limit512 MB
Judgeable
Directed Acyclic GraphHard9
Graph, Topological sort +1No attempts yetTime limit5sMemory limit512 MB
Judgeable
Swapping InversionsHard9
Probability, Combinatorics +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Minimal Cyclic ShiftHard9
String, Number theory +2No attempts yetTime limit1.5sMemory limit256 MB
Judgeable
IntervalHard9
Divide and conquer, Segment tree +2No attempts yetTime limit4sMemory limit512 MB
Judgeable
Nondeterministic Finite AutomatonHard9
Graph, Number theory +1No attempts yetTime limit1sMemory limit256 MB
Judgeable
The StruggleHard9
Bit manipulation, Math +1No attempts yetTime limit4.5sMemory limit512 MB
Judgeable
Power Station of ArtHard9
Graph, Union-find +1No attempts yetTime limit3sMemory limit512 MB
Judgeable
GameHard9
Game theory, Intervals +1No attempts yetTime limit8sMemory limit512 MB
Judgeable
Goldberg Machine 2Hard9
Math, Segment tree +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
MIPT: Connecting PeopleHard9
Minimum spanning tree, Divide and conquer +1No attempts yetTime limit2sMemory limit512 MB
Judgeable
The Last SamuraiHard9
Greedy, Simulation +1No attempts yetTime limit1sMemory limit512 MB
Judgeable
Rational DimasikHard9
Number theory, Math +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Lamb's RespiteHard9
Segment tree, Implementation +2No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Gene FoldingHard9
String, String matching +2No attempts yetTime limit5sMemory limit2048 MB
Judgeable
Deer-Proof FenceHard9
Geometry, Brute force +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Video Quality - Auto (480p)Hard9
Greedy, Intervals +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Island Nations of the Planet BilarbongHard9
Graph, Union-find +2No attempts yetTime limit0.75sMemory limit8 MB
Judgeable
Gets and Puts (Hard)Hard9
ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
QuackQuack (Hard)Hard9
ImplementationNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Kinking CablesHard9
Geometry, Implementation +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
ShootingHard9
Geometry, Math +2No attempts yetTime limit1sMemory limit256 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Joyful NumbersA number n is joyful when appending 25 to its digits gives a square; for the k-th joyful number, report how many distinct primes divide it.	Hard9	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Multiple?Count sequences of length n-k with entries in [1,n] such that no non-empty subsequence sums to a multiple of n, modulo 998244353.	Hard9	CombinatoricsNumber theory+2	No attempts yet	6s	256 MB	Judgeable
Colorful ComponentsCount labeled trees on n colored vertices such that the monochromatic components left after deleting bichromatic edges each have size at most k, modulo 1e9+7.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Brave Seekers of UnicornsCount strictly increasing sequences of distinct integers from 1 to n with no three consecutive elements XORing to zero, modulo 998244353.	Hard9	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Binary Supersonic UtahraptorsAlexey and Boris repeatedly exchange fixed-size groups of yellow or red utahraptors; find the game value \|a_y - b_r\| under optimal play.	Hard9	Game theoryGreedy+2	No attempts yet	1s	512 MB	Judgeable
Workers of the World Unite! Just Not Too Close.Assign n workers to n gates (each gate used once, corridor A or B) and to n workstations, respecting the A-north/B-south adjacency restriction, to minimize total travel distance.	Hard9	Dynamic programmingGreedy+2	No attempts yet	10s	1024 MB	Judgeable
Derangement RotationsCount derangements of size n whose set of derangement rotations has exactly n-2 distinct rotations, modulo a prime p.	Hard9	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
h-indexFor each of q range queries on an array of citation counts, find the largest h such that the range contains at least h values greater than or equal to h.	Hard9	ArraySegment tree+2	No attempts yet	2.5s	512 MB	Judgeable
No Time to DryGiven a color array and Q ranges, find the minimum brush strokes to paint each range where lighter colors can be overpainted by darker ones.	Hard9	StackSegment tree+2	No attempts yet	1s	512 MB	Judgeable
Stone GameCount the opening moves (pile and stone count) that let Bessie force a win in a game where each removed amount must be a multiple of the previous one.	Hard9	Game theoryNumber theory+2	No attempts yet	1s	512 MB	Judgeable
GamesCount the distinguishable piles of K stones drawn from the N given sizes where the first player loses in a Nim variant that removes from at most 6 piles.	Hard9	Game theoryCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
Robot Vacuum 2Given a grid warehouse with boxes and a start cell, output a command string of length N that maximizes the number of distinct cells the vacuum visits.	Hard9	GreedySimulation+2	No attempts yet	12s	1024 MB	Judgeable
Graph GameCount the number of distinct directed graphs on n labeled vertices that can arise as positions in a game where each move adds an edge without creating a cycle.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
Matches Are Not a Toy for ChildrenGiven two figures made of n unit matches, find the minimum number of matches to move so that A coincides with B after a parallel translation.	Hard9	GeometryHash map+2	No attempts yet	2s	1024 MB	Judgeable
PuzzleGiven k undirected graphs with start 1 and end n, find the smallest length T such that some walk of exactly T edges goes from 1 to n in every graph at once.	Hard9	GraphNumber theory+2	No attempts yet	2s	1024 MB	Judgeable
Pearl EmbroideryGiven a tree of pearls embedded in a grid, count for each queried rectangle the number of connected components of the tree induced by the pearls inside it.	Hard9	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
Healthy EatingFor each vending machine on an n by n grid, find the maximum count of machines selling its own product along any shortest path from top-left to bottom-right, then tally how many machines have each such count.	Hard9	Dynamic programmingMatrix+2	No attempts yet	4s	1024 MB	Judgeable
Waging War PeacefullyGiven group sizes A1..AN, find the largest rectangle width Y that fits all soldiers in row-major order with at most k row-boundary conflicts, for every k from 0 to N-1.	Hard9	MathNumber theory+2	No attempts yet	5s	256 MB	Judgeable
Polynomial and Easy QueriesMaintain an array under range applications of f(x)=2x^2-1 and g(x)=4x^3-3x, and answer point queries modulo 100003.	Hard9	MathSegment tree+2	No attempts yet	2s	256 MB	Judgeable
Daily CommuteAfter each of D swaps in a subway route permutation, find the shortest travel time from station 1 to station N using the train and W one-way walkways.	Hard9	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
Boring LessonGiven strings s and t and a list of n favorite strings, find the minimum edit distance from s to t and the largest subset of favorites that can all appear along a shortest edit path, then output that subset in order.	Hard9	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Road ConstructionGiven N points, output the K smallest Manhattan distances among all pairs, in increasing order, for N and K up to 250000.	Hard9	Divide and conquerSorting+2	No attempts yet	10s	2048 MB	Judgeable
Navigation 2Design a flag labeling on an N by N grid so that an agent who sees only its 3x3 neighborhood can walk from any unknown starting cell to a given target using labels alone, minimizing the largest label.	Hard9	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Vote-Value Disparity 2Partition N voter-weighted provinces on a grid into K connected districts minimizing the ratio of largest to smallest district voter total, outputting one district id per province.	Hard9	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Vote-Value Disparity 3Partition N provinces on a grid into K connected electoral districts so that the ratio between the largest and smallest district voter counts is minimized.	Hard9	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Vote-Value Disparity 4Partition N connected provinces into K connected districts to minimize the ratio between the largest and smallest district voter totals, and output any assignment.	Hard9	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Vote-Value Disparity 5Partition the provinces of a grid map into K connected districts to minimize the ratio between the largest and smallest district voter totals.	Hard9	GraphDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Binary SubsequencesFor each K up to 10^6, count binary strings with exactly K distinct non-empty subsequences modulo 1e9+7 and output a shortest such string.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Deque GameGiven two starting stacks over a K-letter alphabet, count for each how many distinct L-length stacks contain that starting stack as a contiguous block, and compare the counts.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
The GradeAfter each insert or erase into a set A, count the ways to place all elements of A into a length-P list padded with zeros so that each positive value sits at least that far from the previous positive value, modulo 1e9+7, or print -1.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
FootballPlayers alternately take students from one class per turn, at most K and no more than the previous turn's count; decide who takes the last student.	Hard9	Game theoryDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
CrossingGiven three seed strings over J,O,I and a crossing operation, decide after each of Q range-assignment updates whether the current string can be produced by repeated crossings.	Hard9	Segment treeMath+2	No attempts yet	3s	512 MB	Judgeable
Broken ClocksGiven n clocks with start times and per-second drift rates, count how many times during a 24-hour window all clocks show the same time.	Hard9	Number theoryMath+2	No attempts yet	3s	512 MB	Judgeable
Forgotten HomeworkGiven a matrix A and the first 2n-1 values of the sequence A^k(i,j), find the missing term A^{2n}(i,j) modulo 1e9+7.	Hard9	MatrixDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
TableCount 2-colorings of an n by m grid with no monochromatic axis-parallel rectangle, modulo a given r, for huge n, m, r.	Hard9	CombinatoricsMath+2	No attempts yet	2s	256 MB	Judgeable
TrisolariansCount the maximum number of distinct life histories (strictly increasing chains of k-vectors with all-positive yearly increments) that end at a vector with coordinate sum n, modulo 7340033.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
Jawaian Weapon SetFind the k-th triple of primes (d1<=d2<=d3) in lexicographic order satisfying three divisibility conditions involving squares minus one.	Hard9	Number theoryMath+2	No attempts yet	3s	256 MB	Judgeable
ParadeGiven a convex polygon, an interior center, and k fixed garland directions, rotate the whole system to minimize the total distance from the center to the polygon boundary along those directions.	Hard9	GeometryBrute force+2	No attempts yet	2s	256 MB	Judgeable
Table 5Build an N by N digit table (2 <= N <= 10) whose rows, columns, and two main diagonals all read as distinct multiples of M, with no leading zeros.	Hard9	BacktrackingMath+2	No attempts yet	1s	512 MB	Judgeable
Table 7Build an N by N digit table (2 <= N <= 10) where every row, column, and main diagonal forms an N-digit multiple of M with no leading zero and all numbers distinct.	Hard9	BacktrackingBrute force+2	No attempts yet	1s	512 MB	Judgeable
Gahui and the Read-Write Game 2Assign each turn to a player so that each player's constrained card order matches, producing the given final list of appended numbers.	Hard9	GreedyImplementation+2	No attempts yet	2.5s	512 MB	Judgeable
TruckGiven a weighted tree with per-edge tolls, handle toll updates and queries asking the minimum fuel to move G gold along a path, modulo 1e9+7.	Hard9	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
TilesCount tilings of a 3 by N grid with 1 by 2 dominoes restricted to white squares, under point color flips and subrectangle queries, modulo 1e9+7.	Hard9	Dynamic programmingSegment tree+2	No attempts yet	4s	1024 MB	Judgeable
Paper, Pen, TriangleGiven a big equilateral triangle of side m and q lines drawn inside it parallel to its sides, count every equilateral triangle fully contained in the figure.	Hard9	CombinatoricsMath+2	No attempts yet	3s	1024 MB	Judgeable
Edge First or Vertex FirstGiven a directed graph, Edgeo picks a probability distribution over edges, then Vertexko picks a distribution over vertices to minimize the expected score; find the game value.	Hard9	Game theoryGraph+2	No attempts yet	8s	512 MB	Judgeable
Feed candiesCandy i has effect (s_i, t_i) generated by a complex recurrence; decide whether a subset sums to (X, Y) and print the chosen indices.	Hard9	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Watching BaseballCount ordered sequences of A+B+C games with A X-wins, B Y-wins, C draws, total runs SX and SY, modulo 1e9+7.	Hard9	CombinatoricsMath+2	No attempts yet	8s	512 MB	Judgeable
Air PollutionEach operation at shop i adds p_i to its two neighbors and subtracts 2p_i from it; find the minimum number of operations so every p_i reaches at least l_i, or -1.	Hard9	MathGreedy+1	No attempts yet	2s	512 MB	Judgeable
Do use segment treeOn a weighted tree, support path assignment to a constant and path queries for the maximum sum of a non-empty contiguous subsequence along the path. n is up to 200,000 and q up to 100,000.	Hard9	Segment treeTree+2	No attempts yet	2s	512 MB	Judgeable
Entangled with LotteryGiven an amidakuji with some horizontal bars already placed, the cat adds K more bars at uniformly random distinct valid heights, and we must compute the maximum over starting bars of the probability that the path ends at the labeled winning bar.	Hard9	Dynamic programmingProbability+2	No attempts yet	2s	512 MB	Judgeable
Tiles are ColorfulOn an M by N grid, each letter appears exactly twice; a move taps an empty cell and removes matching tiles seen first in the four directions, and you want the maximum total tiles removed.	Hard9	SimulationDFS+2	No attempts yet	2s	512 MB	Judgeable
Carpenters' LanguageAfter each of q insertions of a run of '(' or ')' at a given position, decide whether the whole string is a well-formed sentence of the grammar S -> SS \| (S) \| )S( \| epsilon.	Hard9	StringStack+2	No attempts yet	1s	512 MB	Judgeable
Double Magic Made ClearGiven a graph of N elements with compatible pairs, orient each edge to define a spell logic, and maximize the number of ordered pairs (u,v) reachable as a first and last keyword of a valid spell.	Hard9	GraphTopological sort+2	No attempts yet	8s	512 MB	Judgeable
Webby SubwayGiven N polyline subway lines, each a chain of segments, find the minimum number of floors so that lines placed on the same floor have no intersecting or touching segments.	Hard9	GeometryGraph+2	No attempts yet	8s	512 MB	Judgeable
Exact ArithmeticSimulate a stack calculator over numbers of the form a/b plus c/d times sqrt(r), maintaining exact arithmetic and canonical output formatting.	Hard9	ImplementationSimulation+2	No attempts yet	8s	512 MB	Judgeable
Cut outGiven a convex polyhedron as polygonal faces, find the maximum area of its cross section by a plane perpendicular to the z-axis.	Hard9	GeometryMath+2	No attempts yet	8s	512 MB	Judgeable
Strange KeyDecide whether two descriptions of a 3D polyline key, each a set of paths of unit axis-parallel bars, define congruent shapes under rotation and translation.	Hard9	GraphGeometry+2	No attempts yet	2s	512 MB	Judgeable
Bridge Crossing GameTwo players own private sets of directed bridges; from each start island, decide who wins or whether the game never ends, with optimal play.	Hard9	GraphGame theory+2	No attempts yet	1s	1024 MB	Judgeable
Pillar and Wall Defense GameGiven pillars, the wall is the convex hull; each expansion ticket adds rotated pillars at angle a, and we choose the ticket order to maximize the final hull perimeter.	Hard9	GeometryBrute force+2	No attempts yet	1s	1024 MB	Judgeable
Setting an Exam ProblemCount the monotone paths through an N by N grid whose length 2N-1 value sequence has maximum subarray sum exactly K.	Hard9	Dynamic programmingPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Slide CircuitsAfter each range-and-multiple enable or disable operation on slides, report the single disabled slide whose activation makes every building lie on exactly one directed cycle, or X if none does.	Hard9	GraphUnion-find+2	No attempts yet	Not set	1024 MB	Judgeable
Permutation CFGStarting from n and applying a permutation-defined CFG expansion s times, answer queries counting occurrences of integer k in a prefix of the resulting list.	Hard9	RecursionCombinatorics+2	No attempts yet	4s	2048 MB	Judgeable
Sinchon Sequence and QueriesMaintain a sequence under point updates, and for each type 2 query find the maximum sum of a contiguous interval containing position i whose every element is at least j.	Hard9	Segment treeDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
Sinchon Defense HeadquartersGiven N missile points, count the lattice points that lie in the convex hull of the missiles (including boundary) but are not shield locations.	Hard9	GeometryMath+2	No attempts yet	1.5s	1024 MB	Judgeable
Master of String ManipulationCount distinct strings reachable from S after exactly M single-letter increments (z stays z), modulo 1e9+7, with N up to 300 and M up to 1e18.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2.5s	1024 MB	Judgeable
CyclePartition every vertex into vertex-disjoint simple cycles of minimum total weight in a directed weighted graph, and output the cycles.	Hard9	Dynamic programmingGraph+2	No attempts yet	2s	1024 MB	Judgeable
Binary OperatorGroup fully parenthesized expressions with +, * and an arbitrary binary operator # into equivalence classes that agree for every possible meaning of #, then output the lexicographically smallest class numbering.	Hard9	MathHash map+2	No attempts yet	20s	1024 MB	Judgeable
RMQFor each query, sum min times max over every subarray [i, j] with l <= i <= r and s <= j <= e, modulo 1e9+7, given a permutation A.	Hard9	Segment treePrefix sum+1	No attempts yet	3s	1024 MB	Judgeable
DiversityGiven an array and range queries, find the minimum total diversity of each range after its elements are reordered.	Hard9	Segment treeGreedy+1	No attempts yet	7s	512 MB	Judgeable
Calculate! 3Maintain a weighted tree under edge-weight updates and answer how many simple paths have XOR sum equal to a query value c, with weights bounded by 30.	Hard9	TreeBit manipulation+2	No attempts yet	2s	1024 MB	Judgeable
Pizzo CollectorsAssign a category to each '?' house on a cycle of length N (a prime power) and choose non-conflicting collectors, each walking a fixed stride, to maximize total pizzo.	Hard9	Number theoryMath+2	No attempts yet	2s	1024 MB	Judgeable
Tobacco GrowingConstruct a configuration of planted, grass, and flower tiles so that after at most 100 days the harvestable total equals a given N up to 10^18.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
ScreamersGiven a fixed ordered list of edges and many interval queries, count how many contiguous subintervals of the queried slice form a forest (acyclic graph).	Hard9	GraphUnion-find+2	No attempts yet	2s	1024 MB	Judgeable
How to Move the BeansOn a cylindrical grid of dishes, Alice and Bob alternately move beans that may never return to their own previous squares; the task is to find the winner under optimal play.	Hard9	Game theoryGraph+1	No attempts yet	2s	512 MB	Judgeable
Kingdoms and QuarantineGiven a bipartite graph of roads between two kingdoms, find the most roads that can be closed under parity rules and print one valid closing order.	Hard9	MathGraph+1	No attempts yet	8s	512 MB	Judgeable
Crab's CannonGiven a subset of the palindromic prefix lengths of an unknown string of length l, find the minimum number of palindromic prefixes such a string can have.	Hard9	StringString matching+1	No attempts yet	3s	512 MB	Judgeable
ElephantsColor each of n elephants black or white so that every group's black and white counts differ by at most 1, or report -1 if no coloring exists.	Hard9	GraphMath	No attempts yet	3s	256 MB	Judgeable
Interval ShuffleGiven a sequence and m interval operations that each either add 1 to one cell or rearrange the range, find the maximum reachable value of each A_k.	Hard9	GreedySorting+1	No attempts yet	1s	256 MB	Judgeable
Magic BoxGiven a string, count pairs of intervals that spell the same text, grouped by how many squares the two intervals activate, for each count from 0 to n.	Hard9	String matchingString+1	No attempts yet	5s	512 MB	Judgeable
Directed Acyclic GraphGiven a DAG, apply assign or chmin updates to every node reachable from u, and answer point queries for individual node values.	Hard9	GraphTopological sort+1	No attempts yet	5s	512 MB	Judgeable
Swapping InversionsSort a permutation by repeatedly swapping a uniformly random adjacent inversion, where each swap costs the absolute difference of the two values; find the expected total cost modulo 1e9+7.	Hard9	ProbabilityCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Minimal Cyclic ShiftGiven n lengths of random lowercase strings, compute the expected number of answers that still match after the answers are written in a shifted order, modulo 998244353.	Hard9	StringNumber theory+2	No attempts yet	1.5s	256 MB	Judgeable
IntervalGiven n intervals and m queries [A,B], find the expected union length of intervals over a uniformly random sub-range [L,R] within [A,B], modulo 998244353.	Hard9	Divide and conquerSegment tree+2	No attempts yet	4s	512 MB	Judgeable
Nondeterministic Finite AutomatonBuild an n-state NFA over 0 and 1 so that the shortest string it cannot recognize is longer than 18 for n=6 and longer than 400 for n=20.	Hard9	GraphNumber theory+1	No attempts yet	1s	256 MB	Judgeable
The StruggleGiven an ellipse with integer coefficients, compute the sum of (x XOR y)^33 / (x^2 * y) modulo 1e9+7 over all lattice points inside it.	Hard9	Bit manipulationMath+1	No attempts yet	4.5s	512 MB	Judgeable
Power Station of ArtGiven two numbered, red-or-black colored copies of the same graph, decide whether repeated edge swaps can make both copies identical.	Hard9	GraphUnion-find+1	No attempts yet	3s	512 MB	Judgeable
GameKoishi and Satori take turns removing the left or right end of an array, with special sub-segments set as wins or losses; decide the winner of each query [a, b].	Hard9	Game theoryIntervals+1	No attempts yet	8s	512 MB	Judgeable
Goldberg Machine 2After each flip of one arrow in either grid, report the fewest tokens needed for both grids to reach the same arrow configuration, or -1.	Hard9	MathSegment tree+1	No attempts yet	2s	512 MB	Judgeable
MIPT: Connecting PeopleGiven n skyscrapers with floor counts and vertical travel costs, choose n-1 horizontal corridors that keep the city connected and minimize the sum of all pairwise resident travel times.	Hard9	Minimum spanning treeDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
The Last SamuraiDesign a board of at most 200 by 200 with rooks, bishops, and knights so the greedy king strategy makes more than 10^6 moves.	Hard9	GreedySimulation+1	No attempts yet	1s	512 MB	Judgeable
Rational DimasikGiven n fractions, compute the product, over all pairs, of the denominator of their difference written in lowest terms, modulo 998244353.	Hard9	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Lamb's RespiteFor each query, a champion starts at health x with Lamb's Respite clamping health to ceil(x/10) during actions l..r; report final health after all n actions, with point updates to a_i.	Hard9	Segment treeImplementation+2	No attempts yet	3s	1024 MB	Judgeable
Gene FoldingGiven a DNA string, repeatedly fold it at a point where the sequence reads the same in both directions, merging matching nucleotides, and report the shortest length reachable.	Hard9	StringString matching+2	No attempts yet	5s	2048 MB	Judgeable
Deer-Proof FenceGiven up to 9 points and a margin M, partition them into groups and fence each group with the shortest curve keeping distance at least M from every point, minimizing total length.	Hard9	GeometryBrute force+2	No attempts yet	2s	1024 MB	Judgeable
Video Quality - Auto (480p)Given up to 500 viewers with intervals and per-quality satisfaction, choose each viewer's quality over time so total satisfaction is maximized under a shared bandwidth cap.	Hard9	GreedyIntervals+2	No attempts yet	2s	512 MB	Judgeable
Island Nations of the Planet BilarbongMaintain a forest under edge deletions and insertions, where each nation's cities form a subgraph; report the number of connected components per nation after each update.	Hard9	GraphUnion-find+2	No attempts yet	0.75s	8 MB	Judgeable
Gets and Puts (Hard)Design a program that completes within one million execution steps, but the statement gives no task details beyond this limit.	Hard9	Implementation	No attempts yet	1s	1024 MB	Judgeable
QuackQuack (Hard)Within 100000 execution steps, compute an answer for a problem whose statement is missing from the prompt.	Hard9	Implementation	No attempts yet	1s	1024 MB	Judgeable
Kinking CablesBuild a non-self-intersecting polyline from (0,0) to (n,m) inside the room, with marked points at least 1 apart, whose total length is exactly a given value.	Hard9	GeometryImplementation+2	No attempts yet	1s	1024 MB	Judgeable
ShootingFind the minimum launch speed for a projectile under gravity that starts at the first polyline vertex, ends at the last, and stays above every vertex in between.	Hard9	GeometryMath+2	No attempts yet	1s	256 MB	Judgeable