Problems

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Total results29,366 problems

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
Dungeon 3
Hard8
Greedy, Union-find+1
No attempts yet
Time limit
4s
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
Edit Distance Yet Again
Hard8
String, Dynamic programming+1
No attempts yet
Time limit
20s
Memory limit
512 MB
Judgeable
(Almost) Fair Cake-Cutting
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jellyfish
Hard8
Graph, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Social Distancing
Hard8
Tree, Simulation+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
We apologize for any inconvenience
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Slow Down
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
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
Jumping Stones
Hard8
Intervals, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Healthy Lifestyle
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Presidential Game
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Goofy Golf
Hard8
Graph, BFS+1
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
Flip and Combos
Hard8
Segment tree, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dams in Distress
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Exhaustive Experiment
Hard8
Sorting, Greedy+1
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
Travel around China
Hard8
Dynamic programming, Shortest path+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Insects
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Minimum Spanning Tree
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Rectangle Painting
Hard8
Segment tree, Implementation
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Best Subsequence
Hard8
Array, Sorting+2
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Binary Search Tree
Hard8
Segment tree, Tree+1
No attempts yet
Time limit
2s
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
GPA
Hard8
Dynamic programming, Greedy+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
Best Solution Unknown
Hard8
Stack, Greedy+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Bitonic Ordering
Hard8
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Exciting Tournament
Hard8
Dynamic programming, Greedy+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
Agamemnon's Odyssey
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 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
Full Depth Morning Show
Hard8
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 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
Antimatter Rain
Hard8
Sorting, Segment tree+2
No attempts yet
Time limit
7s
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
Daisy's Mazes
Hard8
Graph, BFS+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Restaurants
Hard8
Greedy, Hash map+2
No attempts yet
Time limit
3s
Memory limit
2048 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
Year of the Cow
Hard8
Dynamic programming, Greedy+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
Not the Longest Increasing Subsequence
Hard8
Dynamic programming, Greedy+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
Baby's First Suffix Array Problem
Hard8
String, String matching+1
No attempts yet
Time limit
14s
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
Monster Hunter
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
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
Edge Subsets
Hard8
Dynamic programming, Bit manipulation
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Miner Seok
Hard8
Sorting, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Factorial
Hard8
Number theory, Math+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
Messy kangaroo babies
Hard8
String, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Social Distansering
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
3s
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
Bus Pass
Hard8
Graph, BFS+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
Computational Ichthyology
Hard8
Greedy, Simulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
About Love...
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Number
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
N-gons
Hard8
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Hard Problem
Hard8
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
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
Dungeon 3Find the minimum coins each player needs to walk from floor S to floor T with energy capped at U, buying energy at fountains that cost B_i each.	Hard8	GreedyUnion-find+1	No attempts yet	4s	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
Edit Distance Yet AgainDecide whether the edit distance between two strings is at most k, and if so, output a minimum-length sequence of insert, delete, and replace operations.	Hard8	StringDynamic programming+1	No attempts yet	20s	512 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
JellyfishGiven a connected graph with n vertices and n edges, find the largest set S where every subset T of S can be joined by a connected subgraph that avoids the other vertices of S.	Hard8	GraphTree+2	No attempts yet	2s	512 MB	Judgeable
Social DistancingMove k students on a tree onto the k computer rooms one adjacent step at a time, keeping students at least two rooms apart, or report NO.	Hard8	TreeSimulation+1	No attempts yet	10s	512 MB	Judgeable
We apologize for any inconvenienceGiven tram lines as sets of stops, find after each suspension the largest number of line changes needed between any two mutually reachable stops.	Hard8	GraphShortest path+1	No attempts yet	10s	512 MB	Judgeable
Slow DownRaise some edge weights in a connected undirected graph so the shortest path from node 1 to node N grows by at least 1, paying the total increase, and minimize that cost.	Hard8	GraphShortest path+2	No attempts yet	1s	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
Jumping StonesMaintain a set of present stones under insertions and deletions and answer the minimum jump energy between two present stones, where jumping a gap of length g costs (g-1)^2.	Hard8	IntervalsSorting+2	No attempts yet	2s	512 MB	Judgeable
Healthy LifestyleGiven a connected undirected graph, answer queries asking whether two edge-disjoint paths exist between a pair of vertices.	Hard8	GraphDFS+2	No attempts yet	2s	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
Goofy GolfGoofy's golf ball moves along semicircular strikes between posts and tree tops, and the task asks for the fewest strikes from ball to hole, or -1.	Hard8	GraphBFS+1	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
Flip and CombosMaintain a binary array under range flip operations and answer queries for the longest run of equal bits inside a subarray.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	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
Exhaustive ExperimentGiven leak test results on a grid of components, where helium spreads upward in a cone of slope 1/2, find the fewest leaking components that explain all P and N results.	Hard8	SortingGreedy+1	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
Travel around ChinaGiven a 3 by m grid of city costs, sum the minimum route cost over all ordered pairs of distinct cities, where each visit to a city adds its cost, modulo 1e9+7.	Hard8	Dynamic programmingShortest path+1	No attempts yet	8s	512 MB	Judgeable
InsectsEliminating up to i seed insects, each replaced by a copy at its type's highest remaining level, maximizes total level; output that maximum for each i.	Hard8	GreedySorting+2	No attempts yet	1s	256 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
Rectangle PaintingPaint horizontal runs of cells black on an infinite grid, and report the tallest height h such that some column in a range is black from y=0 up to h, with queries encrypted online.	Hard8	Segment treeImplementation	No attempts yet	12s	1024 MB	Judgeable
Best SubsequenceFor each query range, find the smallest W such that some length-K subsequence has every cyclically adjacent pair summing to at most W.	Hard8	ArraySorting+2	No attempts yet	7s	1024 MB	Judgeable
Binary Search TreeGiven n BSTs, insert a value w into every tree in a range [l, r], or report the sum of node values visited when searching for a in tree x.	Hard8	Segment treeTree+1	No attempts yet	2s	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
GPAGiven n courses with original grade A_i and altered grade B_i, pick a subset to change so the number of days where the new grade falls below the running average of earlier grades is minimized.	Hard8	Dynamic programmingGreedy+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
Best Solution UnknownEach match removes one of two adjacent players, and the stronger one wins and gains 1 strength. List every index that can end as the sole winner.	Hard8	StackGreedy+1	No attempts yet	3s	512 MB	Judgeable
Bitonic OrderingGiven a permutation of distinct cards, find the minimum number of adjacent swaps needed to make the sequence first increasing then decreasing (bitonic).	Hard8	SortingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Exciting TournamentGiven players with distinct skills and per-player game limits, choose any knockout bracket and report the minimum and maximum total XOR excitement over all games.	Hard8	Dynamic programmingGreedy+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
Agamemnon's OdysseyGiven a weighted tree and a limit k, find a walk (any start and end) that uses no edge more than k times and collects the weight of each edge only on its first traversal, maximizing total collected weight.	Hard8	TreeGreedy+2	No attempts yet	1s	1024 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
Full Depth Morning ShowFor each city u in a weighted tree, compute the sum over all other cities v of (t_u + t_v) times the distance between u and v.	Hard8	TreeDFS+2	No attempts yet	3s	1024 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
Antimatter RainDroplets fall straight down; each horizontal sensor disintegrates along with all droplets that reach it, and the rest pass through. For every droplet, report the y-coordinate where it dies, or 0.	Hard8	SortingSegment tree+2	No attempts yet	7s	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
Daisy's MazesGiven a maze of rooms joined by colored one-way doors and a stack-like card deck, find the smallest starting deck size that lets Daisy reach the exit room.	Hard8	GraphBFS+1	No attempts yet	3s	512 MB	Judgeable
RestaurantsFind a stable matching of customers to restaurants with capacities, where both sides have preference lists, and output the assigned customers.	Hard8	GreedyHash map+2	No attempts yet	3s	2048 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
Year of the CowGiven N ancestor years on a line and at most K time jumps between multiples of 12 (Ox years), find the minimum total travel time to visit every ancestor and return to year 0.	Hard8	Dynamic programmingGreedy+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
Not the Longest Increasing SubsequenceGiven an array of n integers from 1 to k, find the fewest elements to delete so that its longest increasing subsequence has length less than k, and list their indices.	Hard8	Dynamic programmingGreedy+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
Baby's First Suffix Array ProblemFor each query substring x = s[l..r], count the suffixes of x that are lexicographically no larger than the suffix s[k..r].	Hard8	StringString matching+1	No attempts yet	14s	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
Monster HunterOn a rooted tree, killing a vertex costs its hp plus the hp of its living children; with up to m free kills by spell, find the minimum total power for every m from 0 to n.	Hard8	TreeDynamic programming+2	No attempts yet	1s	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
Edge SubsetsCount the matchings of a graph with up to 200 vertices where every edge joins vertices differing by A or B, modulo 998244353.	Hard8	Dynamic programmingBit manipulation	No attempts yet	6s	1024 MB	Judgeable
Miner SeokChoose an axis-aligned rectangle anchored at (0,0) whose interior minerals number at most C, maximizing the total beauty of the minerals inside it.	Hard8	SortingBinary search+2	No attempts yet	1s	512 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
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
Messy kangaroo babiesGiven a word S and a list of candidate synonyms, count how many are subsequences of S that can be embedded in at least two different ways.	Hard8	StringDynamic programming+2	No attempts yet	5s	1024 MB	Judgeable
Social DistanseringGiven N students, K queue positions, and M disjoint forbidden intervals, find the largest D such that all N students can be placed at pairwise distance at least D.	Hard8	Binary searchGreedy+2	No attempts yet	3s	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
Bus PassGiven an undirected zone graph and several ordered bus routes, find the center zone and smallest star radius covering every route.	Hard8	GraphBFS+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
Computational IchthyologyAquariums in a row each spawn fish at times set by their population; Igor starts at tank 1, walks one tank per second, and must be present at each birth. Output the time of the first birth he misses.	Hard8	GreedySimulation+2	No attempts yet	2s	1024 MB	Judgeable
About Love...Two moving line segments drift at constant velocities; find the earliest time they touch, or report -1 if they never do.	Hard8	GeometryBinary search+2	No attempts yet	2s	1024 MB	Judgeable
NumberGiven ranges [a,b] and [c,d], find the smallest integer greater than ac that is not a product u*v with u in [a,b] and v in [c,d].	Hard8	MathNumber theory+2	No attempts yet	2s	1024 MB	Judgeable
N-gonsFind the largest multiset of segment lengths from 1 to k that contains no n segments forming a non-degenerate n-gon, and output the lengths in non-decreasing order.	Hard8	GreedyMath+2	No attempts yet	2s	1024 MB	Judgeable
A Hard ProblemPick two rows and two columns so that the four corner cells have the largest possible sum, and report the sum and the rectangle.	Hard8	Brute forceImplementation+2	No attempts yet	1s	1024 MB	Judgeable