Math and counting

Number theory, combinatorics, and geometry

Under construction

Still being built. Things may change

Total results13,160 problems

Dao and Dizzy's Date
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Counting Stars
Hard8
Geometry, Divide and conquer+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Painting Pips
Hard8
Math, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Permutations on the Road: Bob
Hard8
Divide and conquer, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Neural Networks
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Raid
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
3s
Memory limit
768 MB
Judgeable
Broken line
Hard8
Greedy, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Game On Board
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Inv
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Equipments
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Missing Pet
Hard8
Probability, Matrix+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Permutation
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Partition Number
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Stirling Number
Hard8
Number theory, Combinatorics+1
No attempts yet
Time limit
9s
Memory limit
256 MB
Judgeable
All your base are belong to us
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sleeping Cows
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cowmistry
Hard8
Bit manipulation, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Lotte Giants and Gahui
Hard8
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Moon and Sun
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Down We Dig
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Three Machines
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ostap and chairs
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Witch Dance
Hard8
Geometry, Sorting
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Combine The Gears
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Arrange and Count!
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rikka with Game Theory
Hard8
Bit manipulation, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ice Cream Game
Hard8
Game theory, Array+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
The Locksmith
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Space Stations
Hard8
Union-find, Geometry+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Divisor Ritual
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
1.75s
Memory limit
1024 MB
Judgeable
The Formula Sicheol Loved
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
KakaoTalk
Hard8
Geometry, Hash map+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Chair Game
Hard8
Array, Number theory+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Telephone Network Service with Go
Hard8
Graph, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Game Developer Seunghee
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Magenta
Hard8
Game theory, Tree+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sum of Distances
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Minimum Cost Paths
Hard8
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Safety Inspection
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Growing Vegetables is Fun 4
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Drawing Circles
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Perfect Path Patrol
Hard8
Tree, Greedy+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
(Almost) Fair Cake-Cutting
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hallway and Butler
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Forming Compounds
Hard8
Number theory, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Power Link
Hard8
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Presidential Game
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Polygonal Query
Hard8
Geometry, Tree
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Galatea's Diet
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dams in Distress
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Friendship Circles
Hard8
Geometry, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum Spanning Tree
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Circle
Hard8
Geometry, Math
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Game
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Local Maxima
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Miner
Hard8
Intervals, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
One More Problem About DFT
Hard8
Math, Number theory+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Robot
Hard8
Simulation, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Happiness
Hard8
Math, Number theory+1
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Attractions On Plane
Hard8
Geometry, Divide and conquer
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of Colorful Matchings
Hard8
Matrix, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Beautiful Sequence Unraveling
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Biological Software Utilities
Hard8
Combinatorics, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kth Subtree
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Longest Common Subsequence of Permutations
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rainbow Numbers
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ada Loveslaces
Hard8
Combinatorics, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Codenames
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Basic Basis
Hard8
Math, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Solar Energy
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Magic Scale
Hard8
Heap, Sorting+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Paper Snowflakes
Hard8
Simulation, Sorting+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Rule 110
Hard8
Simulation, Math+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Decoration
Hard8
Graph, Number theory
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Non-crossing Segments
Hard8
Geometry, Sorting
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Modern Art 3
Hard8
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fakes and Shidget
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Powerless Mage
Hard8
Sorting, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Premove Checkmate
Hard8
Simulation, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ah, It's Yesterday Once More
Hard8
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fireworks
Hard8
Math, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Harmonious Rectangle
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Just Another Game of Stones
Hard8
Segment tree, Game theory+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bit Operation
Hard8
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Do Use FFT
Hard8
Divide and conquer, Math
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Factorial
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Arthur's Table
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Chocolate Bar Game
Hard8
Game theory, Number theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stern's Sequence
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Teleport Travel
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Atomic Energy
Hard8
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Endgame
Hard8
Math, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Great Wall
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Mafia
Hard8
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fibonacci Strings
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Flying a Drone
Hard8
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bowling
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Decompression
Hard8
String, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dice Password Security
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Theatre
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Dao and Dizzy's DateWalk on a line of N places for T minutes starting and ending at place 1, gaining h[j] whenever you move to place j, and maximize total happiness.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	1024 MB	Judgeable
Counting StarsStars are added over time with beauty values, and each query asks for the total beauty of the stars on or inside the triangle formed by three given stars.	Hard8	GeometryDivide and conquer+1	No attempts yet	6s	1024 MB	Judgeable
Painting PipsGiven N dice and M total pips to distribute across faces, find the maximum expected product of the rolled values.	Hard8	MathDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Permutations on the Road: BobGiven up to N queries returning the inversion count within a subarray, reconstruct the hidden permutation of length N.	Hard8	Divide and conquerMath+2	No attempts yet	2s	1024 MB	Judgeable
Neural NetworksCount labeled layered digraphs in which every node lies on some directed path from layer 1 to layer N, modulo 998244353.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
RaidFor each k from 1 to n, pick k soldiers from a permutation so the number of inversions among them is minimal, then report that minimum and how many selections reach it.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	3s	768 MB	Judgeable
Broken lineAssign each of the up to 16 distinct letters a fixed arrow (right or up) so the area under the resulting monotone staircase path is maximized.	Hard8	GreedyBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Game On BoardCount the minimal initial boards (with the fewest black cells) on an n by m grid from which the closure rule paints every cell black, modulo 998244353.	Hard8	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
InvCount involutions of n elements with exactly k inversions and report the count modulo 2.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
New EquipmentsAssign workers to equipment, where worker i pays a_ij^2+b_ij+c_i on machine j, and report the minimum total cost for each k from 1 to n.	Hard8	GraphShortest path+1	No attempts yet	2s	512 MB	Judgeable
The Missing PetFor each hole on an n by n board, find the expected steps of a random walk from a start cell, given it falls into that hole, modulo 10^9+7.	Hard8	ProbabilityMatrix+1	No attempts yet	4s	512 MB	Judgeable
PermutationCount the ways to fill the unknown positions of a partial permutation so the result has an arithmetic progression subsequence of length 3 or more, modulo 10^9+7.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	3s	256 MB	Judgeable
Partition NumberCount partitions of m into nondecreasing positive parts, where a given set of n values is forbidden as a part, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	3s	256 MB	Judgeable
Stirling NumberGiven n, l, r, and a prime p, compute the sum of unsigned Stirling numbers of the first kind [n, k] for k from l to r, modulo p.	Hard8	Number theoryCombinatorics+1	No attempts yet	9s	256 MB	Judgeable
All your base are belong to usChoose any point in the plane to minimize the sum of distances to the K farthest bases, and output that minimum sum.	Hard8	GeometryBinary search+2	No attempts yet	2s	512 MB	Judgeable
Sleeping CowsCount the maximal matchings between cows and barns, where each cow fits in its assigned barn and no unmatched cow fits in any empty barn, modulo 1e9+7.	Hard8	Dynamic programmingSorting+1	No attempts yet	1s	512 MB	Judgeable
CowmistryCount the sets of three distinct labels, taken from N disjoint integer intervals, where every pair has XOR at most K, modulo 1e9+7.	Hard8	Bit manipulationDivide and conquer+1	No attempts yet	1s	512 MB	Judgeable
Lotte Giants and GahuiCount length-n sequences of positive integers whose gcd is G and lcm is L, printing each answer modulo 1e9+7.	Hard8	MathNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
Moon and SunCount indices i where changing A_i to some other integer in [-100000, 100000] makes the single element of the N-fold difference sequence a multiple of 235813.	Hard8	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Down We DigGiven n 8-character steps, for each prefix of steps determine the winner of a token game where a move from step i to j is legal when the Hamming similarity of the two steps is at least j-i.	Hard8	Game theoryDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Three MachinesCount pairs (a,b) with 1 <= a < b <= m from which three rewrite operations on integer pairs can generate every card (1, a_i).	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Ostap and chairsGiven N x-coordinates and N y-coordinates, find real k and b minimizing the sum of \|x_i - (k*y_i + b)\|.	Hard8	GeometryBinary search+2	No attempts yet	1s	256 MB	Judgeable
Witch DanceGiven N unit-length brooms that rotate clockwise at equal speed around fixed endpoints, decide whether any two brooms ever collide.	Hard8	GeometrySorting	No attempts yet	5s	1024 MB	Judgeable
Combine The GearsGiven a budget b, choose gear sizes with total cost at most b to maximize the number of distinct pointer-direction tuples, output as a natural logarithm.	Hard8	MathNumber theory+2	No attempts yet	2s	256 MB	Judgeable
Arrange and Count!Given a sequence, count modulo 1e9+7 how many distinct orderings the prefix-reversal-then-append operation can produce, over multiple test cases.	Hard8	CombinatoricsMath+2	No attempts yet	5s	512 MB	Judgeable
Rikka with Game TheoryCount the assignments of non-negative integers to the vertices of an undirected graph (n up to 17) where each vertex value equals the mex of its neighbors' values.	Hard8	Bit manipulationDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Ice Cream GameFor each query [L, R], decide the winner of a game that removes ends of an array without deleting the last copy of any kind, or print 0 if a kind is missing.	Hard8	Game theoryArray+1	No attempts yet	3s	1024 MB	Judgeable
The LocksmithMaintain a dynamic set of arithmetic progressions (a mod b) and answer point queries asking whether any active progression contains a given lock number.	Hard8	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
Space StationsEach station is a line segment, two axis-aligned or point contact connects them; for each query decide if two stations lie in the same connected component.	Hard8	Union-findGeometry+2	No attempts yet	2.5s	1024 MB	Judgeable
Divisor RitualGiven N cards with digits 1 to 9, count permutations where the last card's digit divides the number formed by the first N-1 cards, and output that probability.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	1.75s	1024 MB	Judgeable
The Formula Sicheol LovedCompute two nested-sum formulas involving gcd and lcm over all index pairs up to N, each reduced modulo a prime K, for N up to 10^6.	Hard8	Number theoryMath+2	No attempts yet	1s	1024 MB	Judgeable
KakaoTalkGiven N distinct lines, count pairs that intersect (meet at exactly one point), so parallel distinct lines and coincident lines do not count.	Hard8	GeometryHash map+2	No attempts yet	2s	1024 MB	Judgeable
Chair GameFind the fewest participants to add so that some run of K adjacent seated participants is guaranteed to match their chairs at some point as the seats rotate.	Hard8	ArrayNumber theory+1	No attempts yet	3s	1024 MB	Judgeable
Telephone Network Service with GoGiven edge speeds on a complete graph and per-vertex capacities, decide whether the total is N-1 and every vertex subset S has inner edge sum at most \|S\|-1.	Hard8	GraphMath	No attempts yet	1s	1024 MB	Judgeable
Game Developer SeungheePerform M operations on sequence A, each adding Bi to all elements then deleting multiples of 7 unless that would empty the sequence, and report the final sequence modulo 1e9+7.	Hard8	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
MagentaPaula and Marin move tokens on a tree whose edges are blue, red, or magenta, and the task is to decide whether Paula wins, Marin wins, or the game is a draw.	Hard8	Game theoryTree+1	No attempts yet	1s	512 MB	Judgeable
Sum of DistancesGiven K connected graphs, find the sum of shortest distances from (1,...,1) to all vertices in its component of their tensor product, modulo 1e9+7.	Hard8	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Minimum Cost PathsFor each query cell (x, y), find the minimum cost to reach it from (1,1) on an N by M grid, where a column move costs x squared and a row move costs c_y.	Hard8	Dynamic programmingMath	No attempts yet	1s	512 MB	Judgeable
Safety InspectionK carpenters start at coordinate 0 on a line and must finish inspecting Bi items at facility i located at coordinate Ai, where each minute allows one unit of movement or one inspection; find the minimum total time.	Hard8	Binary searchGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Growing Vegetables is Fun 4Given N heights in a row, each operation adds 1 to a contiguous interval; find the minimum number of operations so the final sequence strictly increases then strictly decreases.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Drawing CirclesGiven up to 2000 circles drawn in order, each new circle erases the interior of everything already there; find the total length of circumference still visible.	Hard8	GeometrySorting+2	No attempts yet	5s	1024 MB	Judgeable
Perfect Path PatrolGiven a tree whose edges each need to lie on exactly p patrol paths, find the minimum number of paths (each between two junctions) that achieve all edge demands.	Hard8	TreeGreedy+2	No attempts yet	4s	1024 MB	Judgeable
(Almost) Fair Cake-CuttingGiven n lines cutting a square cake, choose a side of each line to maximize the area left inside the square.	Hard8	GeometrySorting+1	No attempts yet	2s	512 MB	Judgeable
Hallway and ButlerCount the closed walks from room 1 that traverse each edge of a weighted tree exactly w_i times, modulo 998244353.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Forming CompoundsFor each query K, decide whether a set of compound types closed under equal variety can contain exactly K compounds, given atom weights W_i.	Hard8	Number theorySorting+1	No attempts yet	1s	512 MB	Judgeable
Power LinkMaintain generator powers under point updates and answer queries, each asking for the sum of pairwise products of the generators feeding one appliance.	Hard8	MathImplementation+2	No attempts yet	1s	512 MB	Judgeable
Presidential GameTwo players alternately merge 2 to K adjacent elements, John by sum and Preston by XOR, until one value remains; decide who wins when John needs the final value odd.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Polygonal QueryPoints are added one at a time, and for each query the task is to report whether the clockwise or counterclockwise hull path between two hull vertices passes more hull points.	Hard8	GeometryTree	No attempts yet	1s	512 MB	Judgeable
Galatea's DietCount sequences of M candy types from N choices, where a few days have fixed types, so that no two consecutive days share a type, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
Dams in DistressGiven a rooted tree of dams with capacities and current water, find the minimum rain at one node (or the root) that sends at least w water to the root.	Hard8	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
Friendship CirclesGiven n points in the plane, list the indices of every point that a circle can enclose together with p0, with all other points outside the circle.	Hard8	GeometrySorting	No attempts yet	2s	512 MB	Judgeable
Minimum Spanning TreeCount the permutations of edge weights 1 to m under which the first n-1 edges, a spanning tree, are exactly the minimum spanning tree, modulo 998244353.	Hard8	TreeDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
CircleGiven two points A and B and a circle O, find a point C on O's boundary that minimizes the total length of paths from A and B to C that avoid the circle's interior.	Hard8	GeometryMath	No attempts yet	3s	512 MB	Judgeable
GameA robot starts uniformly at random in an array and may stop for A_i or gamble a fair step left or right; maximize the expected score, output modulo 998244353.	Hard8	Dynamic programmingProbability+2	No attempts yet	1s	256 MB	Judgeable
Local MaximaCount permutations of 1 to n*m in an n by m grid that have exactly one local maximum, where a cell is a local maximum if it is at least every other cell in its row and column, modulo a prime P.	Hard8	CombinatoricsMath+1	No attempts yet	4s	512 MB	Judgeable
MinerGiven n intervals and m points, count the nonempty subsets of intervals whose intersection contains at least one of the given points, modulo 998244353.	Hard8	IntervalsSorting+2	No attempts yet	1s	256 MB	Judgeable
One More Problem About DFTGiven a prime p, n dividing p-1, and an array a, the task is to apply the modular DFT with root g^K m times (m up to 1e18) and print the result.	Hard8	MathNumber theory+1	No attempts yet	5s	512 MB	Judgeable
RobotFor each command in a robot's move string, compute the total score the robot would earn if that single command were deleted, where each visit to a cell scores based on visit count and cell coordinates.	Hard8	SimulationPrefix sum+2	No attempts yet	3s	512 MB	Judgeable
HappinessTrack the total happiness of people lying on lines through two teacup centers as the turntable and individual teacups rotate, printing Q+1 values mod 998244353.	Hard8	MathNumber theory+1	No attempts yet	15s	512 MB	Judgeable
Attractions On PlaneGiven N rectangles above the x-axis, find for each one the fraction of the segment from (0,0) to (X,0) during which it is the closest attraction.	Hard8	GeometryDivide and conquer	No attempts yet	2s	512 MB	Judgeable
Number of Colorful MatchingsGiven a bipartite graph whose edges are red or blue, count the perfect matchings for each number k of red edges, modulo 2.	Hard8	MatrixMath+1	No attempts yet	2s	512 MB	Judgeable
Beautiful Sequence UnravelingCount arrays of length n with values from 1 to k where no split point has prefix maximum equal to suffix minimum, modulo the prime p.	Hard8	MathCombinatorics+1	No attempts yet	7s	512 MB	Judgeable
Biological Software UtilitiesCount the labeled trees on n vertices that have a perfect matching, modulo 998244353, for n up to 10^6.	Hard8	CombinatoricsTree+2	No attempts yet	1s	512 MB	Judgeable
Kth SubtreeGiven a tree with n up to 5000 nodes and a rank K, find the size of the Kth smallest connected subgraph (subtree) by node count, or report -1.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Longest Common Subsequence of PermutationsGiven n permutations of the first k uppercase letters, find the length of the longest sequence that is a subsequence of every one of the n strings.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Rainbow NumbersCount integers between two huge bounds (up to 100000 digits) whose decimal digits never repeat consecutively, modulo 998244353.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
Ada LoveslacesCount the symmetric lacing patterns through N eyelet pairs whose lace length and free end length fit each given lace length and the range [f_min, f_max].	Hard8	CombinatoricsBacktracking+1	No attempts yet	2s	1024 MB	Judgeable
CodenamesGiven a Codenames board and hint table, the task computes the winning probability for your team when both spymasters play optimally with random guessing.	Hard8	Game theoryDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
Basic BasisGiven n bit vectors of 4k bits, for each of m query vectors find the smallest prefix index i such that some nonempty subset of the first i vectors XORs to the query.	Hard8	MathBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Solar EnergyGiven N stars each contributing a clipped triangular amount of energy as a function of launch angle, find the angle maximizing the total contribution.	Hard8	GeometrySorting+2	No attempts yet	9s	1024 MB	Judgeable
Magic ScaleGiven N positive weights, list the K smallest distinct subset sums in increasing order, and for each sum output one subset of weights that achieves it.	Hard8	HeapSorting+2	No attempts yet	3s	512 MB	Judgeable
Paper SnowflakesFold a paper strip back and forth at decreasing distances from the loose end, cut it at M positions, and report the total paper length in each resulting pile.	Hard8	SimulationSorting+2	No attempts yet	5s	1024 MB	Judgeable
Rule 110Given a 16-cell starting row and a step count N below 2^60, count the 1-cells after N steps of Rule 110.	Hard8	SimulationMath+1	No attempts yet	3s	512 MB	Judgeable
DecorationGiven N and K, find K distinct spacings below N where each next value is congruent to the previous value plus its divisor count, minimizing the sum, or print -1.	Hard8	GraphNumber theory	No attempts yet	1.5s	512 MB	Judgeable
Non-crossing SegmentsGiven n points with no three collinear, count the segments between pairs of points that cross no other segment.	Hard8	GeometrySorting	No attempts yet	1s	512 MB	Judgeable
Modern Art 3Given a 1D painting of N colors, find the minimum number of brush strokes (each painting one interval in one color, later strokes over earlier ones) needed to reproduce it.	Hard8	Dynamic programmingIntervals+2	No attempts yet	1s	512 MB	Judgeable
Fakes and ShidgetEach of n characters offers two quests with given times and rewards; find the maximum long-run gold per minute when the character each round is chosen uniformly at random.	Hard8	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
Powerless MageGiven n spells with blue, purple, and orange mana costs, find the largest total mana the mage can hold while casting no spell, or report Infinity if there is no upper bound.	Hard8	SortingSegment tree+1	No attempts yet	2s	512 MB	Judgeable
Premove CheckmateOutput a premove queue that checkmates a lone enemy king, whose square in the top-right quarter is unknown, within 50 of your moves.	Hard8	SimulationBrute force+1	No attempts yet	2s	512 MB	Judgeable
Ah, It's Yesterday Once MoreConstruct a legal grid (tree of empty cells, at least two, at most 20x20) so that a random string of 50000 UDLR moves fails to merge all kangaroos at least 25% of the time.	Hard8	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
FireworksEach firework takes n minutes and is perfect with probability p/10000; lighting all made so far takes m minutes and ends the game if any is perfect. Find the minimum expected total time under an optimal stopping strategy.	Hard8	MathProbability+2	No attempts yet	2s	512 MB	Judgeable
Harmonious RectangleCount the 3-colorings of an n by m grid that contain at least one axis-parallel rectangle with a harmonious vertex coloring, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Just Another Game of StonesMaintain an array under range chmax updates, and for each query count first moves that win the Nim game on a subarray plus one extra pile.	Hard8	Segment treeGame theory+2	No attempts yet	5s	512 MB	Judgeable
Bit OperationCount the ways to apply N-1 adjacent merges with AND or OR to a 0/1 array so that the final single value is 1, modulo 998244353.	Hard8	CombinatoricsMath	No attempts yet	2s	1024 MB	Judgeable
Do Use FFTFor each prefix length k, compute the sum over i of C_i times the product of (A_i + B_j) for j from 1 to k, modulo 998244353.	Hard8	Divide and conquerMath	No attempts yet	10s	1024 MB	Judgeable
FactorialOutput a single integer N between 7 and 10^14 that maximizes a score based on how close N! times a power of ten lands to an integer, avoiding floating-point traps.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Arthur's TableGiven a round table's diameter, the number of knights, and the offset of the central platter, find the platter's radius and the first four trenchers' centers and radii.	Hard8	GeometryBinary search+2	No attempts yet	1s	512 MB	Judgeable
Chocolate Bar GameRuby and Dia alternately eat a fully chocolate prime-sized square (each prime used once) or one single square, and the task is to find the winner under optimal play.	Hard8	Game theoryNumber theory+1	No attempts yet	1s	512 MB	Judgeable
Stern's SequenceGiven a reduced fraction p/q, find the index k in Stern's diatomic sequence where b(k)=p and b(k+1)=q, output modulo 998244353.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Teleport TravelA perfect binary tree of height N is given; starting from node 2K-1, find the minimum number of teleports needed to visit every node, taken modulo 1e9+7.	Hard8	TreeDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Atomic EnergyFor each query k, find the minimum total energy when an atom with k neutrons splits into pieces of at most n neutrons, where piece i costs a_i.	Hard8	Dynamic programmingMatrix+1	No attempts yet	2s	1024 MB	Judgeable
EndgameGiven n valid moves on an n by n board, decide whether Alice captures Bob in one turn, forces a tie by teleporting to a cell Bob cannot reach, or loses.	Hard8	MathHash map+1	No attempts yet	1s	1024 MB	Judgeable
Great WallGiven a polyline wall of N points, find the minimum number of guards on a nearby road who together can see every suspected attack point.	Hard8	GeometryGreedy+1	No attempts yet	5s	1024 MB	Judgeable
MafiaGiven accusations of honesty or corruption between cops, count for each queried C the number of size-C corrupt sets consistent with all accusations.	Hard8	GraphUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Fibonacci StringsSum the orders (counts of letter a) of every substring of X that is a Fibonacci string, meaning it has no two adjacent a's, counting each occurrence separately.	Hard8	StringDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Flying a DronePick batteries within a budget to maximize total energy divided by combined drone and battery weight.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	1024 MB	Judgeable
BowlingEach player has G scores that may be permuted independently; for every player find the minimum and maximum number of games they can win, where a win means a strictly higher score than all other players in that game.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
DecompressionInvert a Burrows-Wheeler style permutation by reconstructing the sorted rotation table from the last-column string, then rotate the result so the period comes first.	Hard8	StringSorting+2	No attempts yet	1s	1024 MB	Judgeable
Dice Password SecurityGiven a dictionary of words with no word a substring of another, count how many n-word concatenations have each queried total length.	Hard8	Dynamic programmingString matching+2	No attempts yet	1s	1024 MB	Judgeable
TheatreTwo technicians at opposite wings must switch stage lights between acts, one turning lights on and one off, and each act change must wait for the slower of the two to finish moving; minimize the total break time.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	5s	1024 MB	Judgeable