Problems

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Total results29,425 problems

Jezzball
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Link and Pop -- the Block Game
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
The Rotation Game
Hard8
DFS, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balloons
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Vectors
Hard8
Implementation, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lego Brick Walls
Hard8
Dynamic programming, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Packages Par Avion
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Martian Pranks
Hard8
Binary search, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Runaway Time Machines
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Safety Precautions
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stock Trading
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exam Seating
Hard8
Geometry, Brute force+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Lecture Screens
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Game of Stones
Hard8
Game theory, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Grid Nim
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Circle of Friends
Hard8
Graph, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Floating Mountain Stability
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shortest Paths
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Best Teams
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Fan Groups
Hard8
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prefix Medians
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Puzzle Assembly
Hard8
Backtracking, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
64 MB
Judgeable
Heritage
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
0.3s
Memory limit
64 MB
Judgeable
Cipher
Hard8
Hash map, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Strange Dream
Hard8
Dynamic programming, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Stairways of Saharna
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
0.2s
Memory limit
128 MB
Judgeable
The Bad Scientist
Hard8
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Escaping the Tutoring House
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Islands
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Hi! I'm Luffy! I'm the man who will become the Pirate King!
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ultimate Finishing Strike
Hard8
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Twin Tower
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Clock
Hard8
Geometry, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pie Division
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Escape from the Minefield
Hard8
Geometry, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Pharaoh's Curse
Hard8
BFS, Graph+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
No Smoking, Please
Hard8
Graph, Minimum spanning tree+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Blackjack
Hard8
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robintron
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shepherds and Engineers
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Another Dice Game
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Good Coalition
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hot Dogs in Manhattan
Hard8
Binary search, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
RNG
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Secret Island Base
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stealth Ninja
Hard8
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
In and Out
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bancopia
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Insecurity
Hard8
Bit manipulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hiring
Hard8
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Islands
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Fish
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Balanced Garden in a Row
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pyramid Base
Hard8
Binary search, Geometry+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Flood
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Toy Animals
Hard8
Divide and conquer, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sabotaging the Marathon Training
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Warships
Hard8
Graph, Simulation+2
No attempts yet
Time limit
6s
Memory limit
256 MB
Judgeable
Joining Points
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polish Flag
Hard8
Simulation, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Garden
Hard8
Array, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mountains
Hard8
Segment tree, Binary search+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Birthday
Hard8
Binary search, Sorting+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Artemis
Hard8
Prefix sum, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Empodia
Hard8
Stack, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Twofive
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Depot
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polygon
Hard8
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Prime Square
Hard8
Backtracking, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Circle
Hard8
Brute force, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bubble Sort
Hard8
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Habitat Range of Fish
Hard8
Sorting, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Souvenir Shopping Plan (Gifts)
Hard8
Dynamic programming, Matrix+1
No attempts yet
Time limit
15s
Memory limit
128 MB
Judgeable
JOI National Festival
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Zigzag Numbers
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Icicles
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exposition
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ladder Game
Hard8
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Authentication Level
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Crossing Thin Ice
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bingo Game
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Area and Perimeter of a Union of Rectangles
Hard8
Segment tree, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Moving Cups Across Three Trays
Hard8
BFS, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Altar
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ultimate Device
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Spelling Suggestion
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
12s
Memory limit
128 MB
Judgeable
Fence Making
Hard8
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tree Path
Hard8
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Totally Important Edges
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hexagonal Sticks
Hard8
BFS, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buy Your House
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Highway Patrol
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Boxes and Stones
Hard8
Game theory, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Environment Protection
Hard8
Binary search, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fix the Pond
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Game of Tiles
Hard8
Graph, Game theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Joining Couples
Hard8
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Candy's Candy
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sanghak Language
Hard8
Trie, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
File Search
Hard8
String, Trie+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
JezzballGiven up to ten bouncing atoms, find the earliest time a horizontal or vertical ray from a fixed point can be drawn without any atom touching it.	Hard8	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Link and Pop -- the Block GameSimulate Link and Pop: repeatedly remove the best matching pair (1, 2, or 3 segment link), let blocks slide by their attributes, and print the final board.	Hard8	SimulationImplementation+2	No attempts yet	2s	128 MB	Judgeable
The Rotation GameGiven a 24-cell board, find the shortest sequence of the eight line-rotation moves that makes the eight center cells show the same symbol.	Hard8	DFSBrute force+2	No attempts yet	1s	128 MB	Judgeable
BalloonsGiven two wind vectors and a corridor of width W, find the fastest path from S to X including 30-second penalties for each altitude change.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
VectorsParse and evaluate a small language over scalars and 3D vectors, including mixed operators and bracket styles that can close several open groups at once.	Hard8	ImplementationRecursion+2	No attempts yet	1s	128 MB	Judgeable
Lego Brick WallsDecide whether a rectangular wall can be tiled with given bricks of widths 1 to 3, respecting fixed bricks and the rule that joints in adjacent rows never align, given brick counts.	Hard8	Dynamic programmingBacktracking+1	No attempts yet	1s	128 MB	Judgeable
Packages Par AvionProcess parcels arriving at airport 0, route each to its destination with a shortest-hop tie-break, then fill departing planes by 0/1 knapsack and report each flight's loaded value.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Martian PranksPair rocks between two unit-square snapshots to minimize the maximum move time, where moving a rock costs d(A)+2\|AB\|+d(B), then divide by t.	Hard8	Binary searchGraph+2	No attempts yet	1s	128 MB	Judgeable
Runaway Time MachinesGiven a weighted undirected graph and, for each of several machines, a start and a shortest-path distance, decide whether the distinct destinations are uniquely forced.	Hard8	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
Safety PrecautionsGiven a DAG where each node fails only after at least t dependencies have failed, choose nodes to protect so node n never fails, minimizing protection cost.	Hard8	Dynamic programmingGraph+2	No attempts yet	1s	128 MB	Judgeable
Stock TradingGiven known daily prices for n stocks over D days, starting capital C, and at most t buy or sell actions, maximize final cash.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Exam SeatingFor each data set, score every empty seat by the total readable skill of visible forward students, where lines can be blocked by segments, and report the maximum.	Hard8	GeometryBrute force+1	No attempts yet	3s	128 MB	Judgeable
Lecture ScreensGiven a simple polygon hall, a viewpoint, and directed screens, compute the total fraction of shared content visible across all screens after occlusion by the walls.	Hard8	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
Game of StonesGiven a directed acyclic graph with stones on nodes, two players alternately slide one stone along an edge; decide whether the first player wins.	Hard8	Game theoryGraph+2	No attempts yet	1s	128 MB	Judgeable
Grid NimTwo players alternately remove a heap from either end of a row; a player cannot take three heaps in a row on their own turns, and the first player wins if their coin total is at least the second player's.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Circle of FriendsFor each queried node in an undirected graph, find the largest k-core containing it, then output the largest connected component of that core with its members sorted.	Hard8	GraphImplementation+2	No attempts yet	1s	128 MB	Judgeable
Floating Mountain StabilityGiven up to 49 surviving terms, decide whether they can be a subsequence of a generalized Fibonacci sequence with at most 8 skipped terms between consecutive survivors, and output a valid witness.	Hard8	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Shortest PathsFor each edge on a given shortest a-b path, report the length of the shortest a-b route that avoids that edge.	Hard8	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
The Best TeamsGiven N players each with an age and distinct skill, and forbidden pairs that are adjacent in skill order, answer T queries each asking the maximum sum of at most K players with age at most A.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
Fan GroupsGiven a directed graph and which streets saw fights, output the lexicographically smallest group ordering consistent with the marked fights, or -1.	Hard8	GraphTopological sort+2	No attempts yet	1s	128 MB	Judgeable
Prefix MediansGiven the prefix medians B of an unknown permutation of 1 to 2N-1, reconstruct the lexicographically smallest permutation that produces exactly those medians.	Hard8	GreedyImplementation+2	No attempts yet	1s	128 MB	Judgeable
Puzzle AssemblyGiven four n x n pieces with cut corners, rotate and mirror them to tile a (2n-1) x (2n-1) square with no gaps or overlaps, printing the lexicographically smallest result.	Hard8	BacktrackingImplementation+2	No attempts yet	0.5s	64 MB	Judgeable
HeritageDivide a region under a polygonal line into parcels whose areas match given ratios, choosing vertical cuts that minimize the total fence length.	Hard8	Dynamic programmingGeometry+2	No attempts yet	0.3s	64 MB	Judgeable
CipherFind the a x b subarray that occurs exactly k times (k >= 3) in an n x m character grid and list all its top-left positions in row-major order.	Hard8	Hash mapString+2	No attempts yet	1s	128 MB	Judgeable
Strange DreamCount ways to pick plates from boxes in a forward then backward pass so the recorded product is divisible by k, modulo l.	Hard8	Dynamic programmingNumber theory+1	No attempts yet	1s	128 MB	Judgeable
The Stairways of SaharnaSplit a sequence into k disjoint non-decreasing subsequences to maximize the total number of chosen elements, and output this maximum for every k up to the point where all n elements are used.	Hard8	Dynamic programmingGreedy+2	No attempts yet	0.2s	128 MB	Judgeable
The Bad ScientistGiven a graph of contradictions, delete at most k vertices to remove all edges and report the smallest such set size, or IMPOSSIBLE.	Hard8	GraphBrute force+2	No attempts yet	1s	128 MB	Judgeable
Escaping the Tutoring HouseFind whether a tutor can reach the exit while keeping all kids inside a forward half-plane at every instant, and if so, the shortest such path.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
IslandsGiven non-overlapping simple polygons as islands, find the minimum total water distance to travel from one island to another, since walking on land is free.	Hard8	GeometryShortest path+1	No attempts yet	3s	128 MB	Judgeable
Hi! I'm Luffy! I'm the man who will become the Pirate King!Given island coordinates and left-of constraints per map, list every island that can be the viewpoint so all listed islands lie in a forward half-plane and constraints hold.	Hard8	GeometrySorting+1	No attempts yet	1s	128 MB	Judgeable
Ultimate Finishing StrikeGiven a rectangular room, start and target points, and a required number of wall bounces, find all bounce-count vectors for the shortest reflecting path.	Hard8	MathGeometry+2	No attempts yet	1s	128 MB	Judgeable
The Twin TowerCount perfect matchings of a 3x3xN grid graph where each of the 9N rooms pairs with an adjacent room, modulo 10007.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
ClockFind the largest empty circle fully inside a rectangular wall that avoids up to 50 non-overlapping discs, using a generalized Voronoi diagram of points, segments, and circles.	Hard8	GeometryDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
Pie DivisionCount the number of straight lines that split 2N labeled points (N of each of two colors, N even) so that each open half-plane holds N/2 points of each color, treating both sides as the same split.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
Escape from the MinefieldEach mine kills within 2 meters; find the largest disk centered at the origin (radius r) that can slide clear of all mines, then output floor(pi r^2).	Hard8	GeometryGraph+2	No attempts yet	2s	512 MB	Judgeable
The Pharaoh's CurseOn a small grid, S pushes up to two sarcophagi onto buttons while stepping around them, and must reach the exit with all buttons held; find the minimum steps or report impossible.	Hard8	BFSGraph+2	No attempts yet	5s	128 MB	Judgeable
No Smoking, PleaseGiven a grid whose adjacent rooms are joined by passages of known area, split rooms into two connected zones separating entrance from kitchen, paying 1000 per unit passage area plus 1000 per cut passage.	Hard8	GraphMinimum spanning tree+1	No attempts yet	3s	512 MB	Judgeable
BlackjackGiven the exact order of the remaining deck, decide which hands to play, how much to bet, and when to hit or stand, to maximize total profit.	Hard8	Dynamic programmingGame theory+2	No attempts yet	1s	128 MB	Judgeable
RobintronGiven planets orbiting a star at constant angular speeds, find the minimum time for the Robintron to hop between gravity wells from the first planet to the last, rounding up to whole days.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Shepherds and EngineersGiven s sheep needed in town after b bridges whose tolls follow a strict divisibility rule, find the minimum starting number of sheep.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Another Dice GameCompute the probability that Jan reaches a target score of n in Pickomino with optimal play, given the dice, set-aside and worm rules.	Hard8	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Good CoalitionEach party has seats and a survival probability; find the party subset holding at least 76 seats whose product of probabilities is maximized, and print it as a percentage.	Hard8	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
Hot Dogs in ManhattanGiven existing stands on a w by h grid, choose two empty intersections maximizing the smaller of the two minimum distances to all other stands.	Hard8	Binary searchGeometry+2	No attempts yet	2s	128 MB	Judgeable
RNGGiven y and a, b, c, n, find all x in [0, 2^n) with a x^2 + b x + c = y mod 2^n, printing x only when exactly one solution exists.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Secret Island BaseFor each simple polygon, find the radius of the largest circle that fits entirely inside it, the so-called Chebyshev center.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
Stealth NinjaGiven guards patrolling a grid with periodic vision, decide whether a ninja can walk from the front wall to the back wall unseen.	Hard8	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
In and OutFind the shortest round trip from node 1 to node N and back, where each sentry node is visited at most once across both legs.	Hard8	GraphShortest path+1	No attempts yet	1s	128 MB	Judgeable
BancopiaPlace up to m police posts, each halving one road's robbery probability, so that the safest a-to-b route has the smallest possible robbery probability.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
InsecurityGiven a hexadecimal bitstring and lists of usernames and passwords, find which username concatenated with which password encrypts to that string under a growing left-shift XOR scheme.	Hard8	Bit manipulationBrute force+2	No attempts yet	1s	128 MB	Judgeable
HiringChoose a real wage coefficient k and a subset of workers so that each hired worker's pay Q_i*k meets their minimum S_i and the total pay stays within budget W, maximizing the subset size.	Hard8	SortingGreedy+2	No attempts yet	1s	128 MB	Judgeable
IslandsEach island has one undirected weighted edge; find the maximum-weight walk choosing one edge per component/tree path structure respecting ferry reachability rules.	Hard8	GraphGreedy+2	No attempts yet	2s	128 MB	Judgeable
FishGiven fish lengths and gem kinds, count how many distinct gem-count combinations a single fish can ever hold, modulo M, where a fish can eat another only if at least twice as long.	Hard8	Dynamic programmingSorting+2	No attempts yet	3s	128 MB	Judgeable
Balanced Garden in a RowCount balanced binary strings of length N whose every substring has at most two more L than P, and find the lexicographic rank of a given string modulo M.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Pyramid BaseGiven up to 1000 weighted rectangles on a grid up to 10^6 by 10^6, find the largest axis-aligned square whose total cost of intersected rectangles is at most B.	Hard8	Binary searchGeometry+2	No attempts yet	5s	128 MB	Judgeable
FloodGiven a non-crossing grid-aligned wall network, determine which walls survive after water bursts outward-inward hour by hour until all regions flood.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Toy AnimalsCount pairs of points on a 1D, 2D, or 3D integer grid whose Manhattan distance is at most D.	Hard8	Divide and conquerSorting+2	No attempts yet	2s	128 MB	Judgeable
Sabotaging the Marathon TrainingGiven a spanning tree of paved edges plus weighted unpaved edges, delete cheap unpaved edges so that no even-length simple cycle remains.	Hard8	GraphDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
WarshipsEach warship is an axis-aligned or diagonal segment in an n by n grid; each horizontal or vertical laser shot removes all ships touching that line, and you report the heaviest weight removed per shot.	Hard8	GraphSimulation+2	No attempts yet	6s	256 MB	Judgeable
Joining PointsGiven two sets of colored points in general position inside a square, output a non-crossing spanning tree for each color separately.	Hard8	GeometryGreedy+2	No attempts yet	1s	128 MB	Judgeable
Polish FlagThree children grow regions of blocks from three fixed edges with priority rules and simultaneous expansion each turn; count each child's white (top) and red (bottom) cells.	Hard8	SimulationGeometry+2	No attempts yet	2s	128 MB	Judgeable
GardenPlace two non-overlapping rectangles, each holding exactly k roses, and minimize the sum of their perimeters over an l by w grid with n roses.	Hard8	ArrayPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
MountainsMaintain a piecewise-constant sequence of elevation changes under range assignments, and after each update find the first prefix-sum position whose elevation exceeds a query height h.	Hard8	Segment treeBinary search+2	No attempts yet	3s	256 MB	Judgeable
BirthdayChildren sit around a round table in order 1..n; reseat them into a given cyclic order while minimizing the largest distance anyone walks along the circle.	Hard8	Binary searchSorting+2	No attempts yet	2s	64 MB	Judgeable
ArtemisGiven N points with distinct x and y, find the axis-parallel rectangle with two opposite corners on points that contains at least T points and the fewest total points.	Hard8	Prefix sumBinary search+2	No attempts yet	2s	128 MB	Judgeable
EmpodiaGiven a permutation biosequence, find every minimal framed interval: a segment whose endpoints are its min and max and that contains no shorter framed interval.	Hard8	StackArray+2	No attempts yet	1s	128 MB	Judgeable
TwofiveMap between a valid 5x5 standard Young tableau word and its rank, the count of valid words lexicographically before it.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
DepotGiven the final row placement produced by the depot insertion rule, count how many arrival orders of the containers could have produced it.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
PolygonRemove one edge of a polygon, then repeatedly merge adjacent vertices by the intervening + or *, and report the maximum final value plus every edge whose removal reaches it.	Hard8	Dynamic programmingIntervals+2	No attempts yet	1s	128 MB	Judgeable
Prime SquareFind all 5x5 digit grids whose five rows, five columns and two diagonals are five-digit primes with the same given digit sum and a fixed top-left digit, printed in lexicographic order.	Hard8	BacktrackingNumber theory+2	No attempts yet	1s	128 MB	Judgeable
The CircleChoose n positive sector values (each at least k) so that consecutive circular block sums cover every integer from m to i, maximizing i.	Hard8	Brute forceCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Bubble SortSwap exactly one pair of elements in the array, then find the minimum number of swaps the given bubble sort performs on the result.	Hard8	SortingPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Habitat Range of FishGiven up to 50 axis-aligned boxes in 3D, compute the total volume covered by at least K of them.	Hard8	SortingDivide and conquer+1	No attempts yet	1s	128 MB	Judgeable
Souvenir Shopping Plan (Gifts)On an H by W grid with blocked houses, move from the top-left to the bottom-right, taking at most K steps north or west, and maximize the number of distinct souvenir shops visited.	Hard8	Dynamic programmingMatrix+1	No attempts yet	15s	128 MB	Judgeable
JOI National FestivalGiven a connected weighted graph with some festival cities, answer queries asking for the largest possible minimum distance-to-festival along any path between two cities.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Zigzag NumbersCount numbers in [A, B], up to 500 digits, that are divisible by M and whose adjacent digit comparisons alternate up then down.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	128 MB	Judgeable
IciclesIcicles grow each hour when strictly longer than both neighbors and snap at length L; find the hour when all have broken.	Hard8	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
ExpositionSplit N points in the plane into two nonempty groups minimizing the largest Manhattan distance within any group.	Hard8	Binary searchGeometry+1	No attempts yet	1s	128 MB	Judgeable
Ladder GameGiven a ladder with n lines and m rungs, erase at most one rung to minimize the sum of scores reached from the leftmost k starting lines.	Hard8	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
Authentication LevelTwo grids each have a starting cell; pick a threshold per grid so the reachable cells sum to at least R, minimizing the sum of thresholds.	Hard8	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
Crossing Thin IceGiven an m by n grid of ice cells, find the longest path that starts anywhere and only steps onto unbroken ice, breaking each visited cell.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Bingo GameCount N x N grids with distinct values from 1 to M, columns increasing downward, each column larger than all columns to its left, and total sum S, modulo 100000.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Area and Perimeter of a Union of RectanglesGiven up to 10000 axis-parallel rectangles on an integer grid, compute the area of their union (and its perimeter when r=2), counting overlaps once.	Hard8	Segment treeSorting+2	No attempts yet	1s	128 MB	Judgeable
Moving Cups Across Three TraysCups of sizes 1..n sit stacked (largest on top) on three trays; with moves allowed only between A-B and B-C, find the minimum number of moves to gather every cup onto A or C, or report -1 if more than m are needed.	Hard8	BFSDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
AltarCount the sequences of nonnegative column heights reachable by repeatedly raising the interior of any equal-height range by 1, matching known heights where not stolen (-1).	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Ultimate DeviceEach of n distinct cycle lengths is chosen by a fair coin; find the expected LCM of the chosen subset, output as (r * 2^n) mod 10007 or "not integer".	Hard8	Dynamic programmingMath+2	No attempts yet	10s	128 MB	Judgeable
Spelling SuggestionGiven weighted edit costs including keyboard-aware substitution and transposition, find the dictionary words closest to each query word.	Hard8	Dynamic programmingString+2	No attempts yet	12s	128 MB	Judgeable
Fence MakingFor each integer radius and spacing pair, count holes drilled through repeated remelting of the strip, then sum C(d,r,S) over all pairs.	Hard8	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
Tree PathGiven a directed tree, find the minimum number of reversed-edge paths to add so that every node can reach every other node.	Hard8	TreeGraph+2	No attempts yet	1s	128 MB	Judgeable
Totally Important EdgesGiven a directed flow network, count the edges whose capacity decrease by 1 lowers the maximum flow by exactly 1.	Hard8	GraphShortest path+1	No attempts yet	1s	256 MB	Judgeable
Hexagonal SticksGiven at most 8 unit sticks on an infinite hexagonal grid with blocked cells, find the minimum number of moves (rotate, push, or discard) so the sticks form one closed regular hexagon.	Hard8	BFSBrute force+2	No attempts yet	1s	128 MB	Judgeable
Buy Your HouseFor each of up to 500 tests with at most 50 non-overlapping axis-aligned houses, count integer-coordinate rectangles that contain exactly one house and split none, modulo 1e9+7.	Hard8	GeometryCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Highway PatrolChoose a subset of directed edges to patrol, containing all forced edges and at least one edge, with equal patrolled in-degree and out-degree at every vertex, minimizing total patrol plus surveillance cost.	Hard8	GraphDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Boxes and StonesCount the initial distributions of S indistinguishable stones among the first B-1 boxes from which Carole, moving second each round, can force a win against Paul.	Hard8	Game theoryCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Environment ProtectionGiven rational function boundaries of two underground layers, find the digging depth d so the exposed middle-layer area equals a target A, printed to five decimals.	Hard8	Binary searchMath+2	No attempts yet	1s	128 MB	Judgeable
Fix the PondGiven a grid of rotatable barriers in a 2N by 2N+1 pond, find the minimum number of barriers to rotate so a path visits every cell once from top-left to bottom-left.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Game of TilesTwo players alternately extend a path of numbered tiles on a grid with blocked cells; the player unable to move loses. Determine the winner under optimal play.	Hard8	GraphGame theory+2	No attempts yet	1s	128 MB	Judgeable
Joining CouplesEach city has one directed outbound flight, forming a functional graph; for each query find the minimum combined distance from two starting cities to any common reachable city, or -1.	Hard8	GraphTree+2	No attempts yet	1s	128 MB	Judgeable
Candy's CandyCount the ways to split F flavors' counts into equal-size packs, some single-flavor and at least one containing all flavors, with each flavor having a flavored pack.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Sanghak LanguageCount the distinct strings formed by concatenating any nonempty prefix of a Namgyu word with any nonempty suffix of a Jaehyeok word, summing over several test cases.	Hard8	TrieString+2	No attempts yet	1s	128 MB	Judgeable
File SearchCount how many non-empty subsets of the files can be exactly the result set of some substring query.	Hard8	StringTrie+2	No attempts yet	5s	128 MB	Judgeable