Problems

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Total results29,425 problems

Garden Fence
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Hedge Mazes
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Electric Needs
Hard8
Binary search, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Code Lock
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
File Recover
Hard8
String, String matching+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Grapevine
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hooligan
Hard8
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Abwords
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
DNA Subsequence
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Higgs Boson
Hard8
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ambiguous Codes
Hard8
String, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Power Generation
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Mission Impossible
Hard8
Geometry, Union-find+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Optical Fiber
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Light Up
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Petanque
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Zing Zhu's Oyster Farm
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cutting Edge
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Secure Region
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Runner Pawns
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kryptonite Mine
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Square Lottery
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Movers
Hard8
Geometry, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Monkey Business
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fat Ninjas
Hard8
Geometry, Union-find+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Slithering Serpent
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pahom on Water
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Detour Buster
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Numbers Game
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
The Crayfish Scrivener
Hard8
Stack, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jousting Tournament
Hard8
Array, Simulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Rotation Parity
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Spies
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Race
Hard8
Tree, Divide and conquer+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
The Crocodile's Underground City
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Elephants
Hard8
Segment tree, Dynamic programming+2
No attempts yet
Time limit
12s
Memory limit
256 MB
Judgeable
Photo
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Figure Eight
Hard8
Prefix sum, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hill Walk
Hard8
Sorting, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Partitioning the Farm
Hard8
Brute force, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Taxi
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Route Design
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gangs of Cowstantinople
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
First!
Hard8
String, Trie+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crazy Fences
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Scrambled Letters
Hard8
String, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balanced Trees
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balanced Cow Subsets
Hard8
Backtracking, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Unlocking Blocks
Hard8
BFS, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Large Banner
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tractor
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Run
Hard8
Game theory, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Delivery Route
Hard8
BFS, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Junkyu and the Apples
Hard8
DFS, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Farm Management
Hard8
Tree, Segment tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Beauty Pageant
Hard8
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buying Feed
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Candy
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Continental Cowngress
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Roads and Planes
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Lost Cows
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Triangle
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cow Treats
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Allowance
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Who Brings the Cookies?
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lights
Hard8
Bit manipulation, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coin Game
Hard8
Dynamic programming, Game theory+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Cow Toll Paths
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shipping Around an Island
Hard8
BFS, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cow Telephones
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Barn Allocation
Hard8
Greedy, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
StarCowraft
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Test Taking
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rocks and Trees
Hard8
Game theory, Tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Water Slides
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangle Counting
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Holedox Moving
Hard8
BFS, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Game Prediction
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Winning Checkers
Hard8
DFS, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jigsaw Puzzles
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Checkers
Hard8
DFS, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Earthquake Damage
Hard8
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Safe Travel
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Pink Floyd
Hard8
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Surround the Islands with Fence
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Exams
Hard8
Bit manipulation, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Earthquake Damage 2
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Payback
Hard8
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Holiday Painting
Hard8
Segment tree, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Telephone Line
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sightseeing Cows
Hard8
Graph, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Treasure
Hard8
Graph, Trie+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Haybale Guessing
Hard8
Binary search, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Artificial Lake
Hard8
Stack, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hotel
Hard8
Segment tree, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Grabbing Land
Hard8
Sorting, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Flood Fill
Hard8
Union-find, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Milk Patterns
Hard8
String matching, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Silver Lilypad Pond
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fire Evacuation Plan
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Garden FenceChoose a line through two boundary points splitting the field into two sides; minimize the total value of trees cut down.	Hard8	GeometrySorting+1	No attempts yet	5s	128 MB	Judgeable
Hedge MazesFor each query (S,T) decide whether the undirected graph has exactly one simple path between S and T, and print Y or N per query.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Electric NeedsNumber all empty cells of a huge grid by Chebyshev distance to the nearest of up to 20 power plants, breaking ties by row then column, and answer positional queries.	Hard8	Binary searchGeometry+2	No attempts yet	1s	128 MB	Judgeable
Code LockGiven a target lowercase string starting from all 'a', find the minimum number of moves where each move shifts a contiguous block of wheels up or down by one.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
File RecoverCount the distinct contiguous substrings that occur at least twice in a given string, for several test cases up to 100000 characters each.	Hard8	StringString matching+1	No attempts yet	5s	128 MB	Judgeable
GrapevineGiven a monotone matrix of heights and height-interval queries, find for each query the largest square submatrix whose heights all fall in the interval.	Hard8	Binary searchDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
HooliganGiven partial results of a round-robin tournament where each pair plays M times, decide whether team 0 can finish alone in first place.	Hard8	GraphGreedy+2	No attempts yet	1s	128 MB	Judgeable
AbwordsGiven N, find the minimum word length over A/B words (starting with A, length at least 2) that admits an N-step cycle of the two given transformations.	Hard8	MathCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
DNA SubsequenceFind the longest common subsequence of two words where every maximal matched run must be a contiguous block of at least K characters in both words.	Hard8	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
Higgs BosonGiven two particles whose polar radius and angle move linearly in time, find the earliest rational time t >= 0 when their positions coincide, or report that they never do.	Hard8	MathGeometry+2	No attempts yet	1s	128 MB	Judgeable
Ambiguous CodesDecide whether a set of hexadecimal code words is ambiguous, and if so report the length of the shortest message with two distinct decodings.	Hard8	StringGraph+2	No attempts yet	1s	128 MB	Judgeable
Power GenerationBuild the tree formed by attaching each new plant to the nearest older one, then split it into the most connected subtrees each having total capacity at least C.	Hard8	TreeDynamic programming+2	No attempts yet	3s	128 MB	Judgeable
Mission ImpossibleGiven a simple polygon border, radar disks that block movement, and informers inside, decide which reachable informer lies farthest from the border, starting from (2000, 2000).	Hard8	GeometryUnion-find+2	No attempts yet	3s	128 MB	Judgeable
Optical FiberGiven a tree of cities, each with up to 50 candidate router sites, pick one site per city to minimize the sum of Euclidean edge lengths.	Hard8	Dynamic programmingTree+2	No attempts yet	1s	128 MB	Judgeable
Light UpOn a board up to 7 by 7 with numbered barriers, find the minimum number of lamps that light every empty square, where no two lamps see each other and each numbered barrier has an exact count of adjacent lamps, or report no solution.	Hard8	BacktrackingBrute force+2	No attempts yet	1s	128 MB	Judgeable
PetanqueSimulate seven petanque throws where a moving ball travels along its direction, possibly striking other balls and transferring its remaining roll, then decide who owns the closest boule to the coche and count points.	Hard8	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Zing Zhu's Oyster FarmGiven horizontal and vertical fence segments with heights, find the total area of land enclosed by cycles of segments that all stand at least as tall as the tide.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
Cutting EdgeGiven non-overlapping rectangles that tile a big pane, output the sequence of edge-to-edge cuts (smallest X1, then smallest Y1 first) that separates every rectangle.	Hard8	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Secure RegionGiven an axis-aligned field and up to 300 mines, find the axis-aligned mine-free rectangle with the largest shorter side, then the largest longer side.	Hard8	GeometryBinary search+2	No attempts yet	1s	128 MB	Judgeable
Runner PawnsOn an 8x8 board with up to 8 pawns advancing one row per round, find the minimum knight moves to capture all pawns, or report impossible.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Kryptonite MineFind the route from start to exit that minimizes walking distance, using at most N teleports between booths that share an unobstructed line of sight.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
Square LotteryCount, over all permutations of 1 to N^2 on an N by N grid, the expected number of winning tickets for a random set of four corners forming a square, then divide the prize pool.	Hard8	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
MoversFor each box in order, decide whether it can be slid from the open left side to its destination without overlapping placed boxes or walls, and list the rejects.	Hard8	GeometrySimulation+2	No attempts yet	1s	128 MB	Judgeable
Monkey BusinessCount the ways to distribute exactly B fruits and vegetables among G groups so each group satisfies the per-group rules and totals, modulo a prime.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Fat NinjasGiven point sensors in an N by N square, find the diameter of the largest circle that can travel from the left side to the right side without touching any sensor.	Hard8	GeometryUnion-find+2	No attempts yet	3s	128 MB	Judgeable
Slithering SerpentGiven a self-avoiding snake path of at most 37 steps, find the minimum number of moves to steer it into a position that is doomed to crash.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Pahom on WaterDecide whether Pahom can travel from the red pad to the violet pad and back, stepping only to strictly higher frequencies outbound and strictly lower ones inbound, with each non-red pad vanishing after he leaves it.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Detour BusterGiven a piecewise-linear track, find the shortest distance from the first point to the last while staying on the track, allowing travel in either direction.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
Numbers GameGiven 4 to 7 integers, combine each at most once with +, -, *, or truncated integer division to reach a value as close as possible to a target, printing the smaller value on ties.	Hard8	BacktrackingBrute force+2	No attempts yet	5s	128 MB	Judgeable
The Crayfish ScrivenerProcess type and undo commands, including nested undos, and answer queries for the character at a given position.	Hard8	StackTree+2	No attempts yet	2s	512 MB	Judgeable
Jousting TournamentGiven the starting order of N-1 knights and C fixed round intervals, find the smallest insertion position for a late knight with skill R that maximizes the number of rounds it wins.	Hard8	ArraySimulation+2	No attempts yet	1s	256 MB	Judgeable
Rotation ParityDecide the parity of the number of 2x2 clockwise rotations needed to sort a permutation of an R x C grid into row-major order.	Hard8	MathCombinatorics+2	No attempts yet	5s	256 MB	Judgeable
SpiesChoose meetings so spies exchange information, plus a set of spies to send, so the sent spies know everything the unsent spies obtained; minimize total cost.	Hard8	GraphMinimum spanning tree+2	No attempts yet	5s	128 MB	Judgeable
RaceGiven a weighted tree, find a path of total length exactly K that uses the fewest edges, or report -1 if none exists.	Hard8	TreeDivide and conquer+2	No attempts yet	3s	256 MB	Judgeable
The Crocodile's Underground CityFind the minimum guaranteed escape time from room 0 to any exit room when a gatekeeper blocks one corridor at each room before Chulsoo moves.	Hard8	GraphShortest path+2	No attempts yet	2s	256 MB	Judgeable
ElephantsAfter each of M moves that relocate one elephant, report the minimum number of length-L segments needed to cover all current positions.	Hard8	Segment treeDynamic programming+2	No attempts yet	12s	256 MB	Judgeable
PhotoGiven intervals each containing exactly one marked point, find the maximum number of marked points, or -1 if no assignment is consistent.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Figure EightFind two axis-aligned rectangles sharing one horizontal edge row, outlines all flawless, maximizing the product of the two interior areas.	Hard8	Prefix sumImplementation+2	No attempts yet	1s	128 MB	Judgeable
Hill WalkGiven non-crossing slanted segments, simulate Bessie climbing each hill and falling straight down at its upper end, counting the distinct hills she touches.	Hard8	SortingBinary search+2	No attempts yet	1s	128 MB	Judgeable
Partitioning the FarmPlace at most K full-width horizontal or vertical fences on an N x N grid to minimize the largest connected group of cows.	Hard8	Brute forceBinary search+2	No attempts yet	1s	128 MB	Judgeable
TaxiBessie drives one cow at a time along a fence of length M, may drop cows short of their goals, starts at 0 and ends at M; find the minimum total driving distance.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Route DesignGiven two banks of valued sites and a set of non-crossing routes, find the maximum total value of a tour that alternates between banks without intersecting routes.	Hard8	Dynamic programmingSorting+2	No attempts yet	1s	128 MB	Judgeable
Gangs of CowstantinopleGiven gang sizes, decide if gang 1 can control the field at the end, and find the lexicographically earliest arrival order maximizing the surviving gang-1 cows.	Hard8	GreedyImplementation+2	No attempts yet	1s	128 MB	Judgeable
First!Given up to 30000 strings, find every string that can become lexicographically smallest under some permutation of the 26-letter alphabet.	Hard8	StringTrie+2	No attempts yet	1s	128 MB	Judgeable
Crazy FencesFences form disjoint closed polygons; find the largest set of cows that can reach each other without crossing a fence.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
Scrambled LettersGiven N scrambled names, find for each the lowest and highest rank its original anagram could occupy in an alphabetical ordering of all cows.	Hard8	StringSorting+2	No attempts yet	1s	128 MB	Judgeable
Balanced TreesGiven a tree whose nodes are labeled with parentheses, find the maximum nesting depth over all paths that spell a balanced parenthesis string.	Hard8	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Balanced Cow SubsetsCount how many subsets of up to 20 cows can be split into two groups with equal total milk output.	Hard8	BacktrackingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
Unlocking BlocksGiven three connected polyomino shapes on a small grid, find the minimum total number of unit slides that makes their bounding boxes pairwise non-overlapping, or -1 if impossible.	Hard8	BFSSimulation+2	No attempts yet	1s	128 MB	Judgeable
Large BannerCount pairs of lattice posts in an (M+1) by (N+1) grid whose segment contains no other post and whose Euclidean length lies in [L, H], modulo B.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
TractorGiven up to 50,000 hay bales on a 1000 by 1000 grid, find the fewest bales to remove so an axis-parallel path from the tractor's start to the origin exists.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
Cow RunGiven N rounds, each with 8 cards, pick for each round whether Farmer John keeps the top or bottom 4 so that the cows always finish within distance K of the start, regardless of Bessie's choices.	Hard8	Game theoryDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Delivery RouteFind the shortest 4-directional grid path that visits farms 1..N in order and back to farm 1, never stepping on any other farm's cell; output -1 if impossible.	Hard8	BFSShortest path+2	No attempts yet	1s	128 MB	Judgeable
Junkyu and the ApplesOn a 5x5 grid with K blocked cells (K even, up to 22), count the ways two harvesters starting at opposite corners can each tour all open cells and meet at the end.	Hard8	DFSBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Farm ManagementA tree of N farms gets path updates that add 1 to every edge on a path, plus path queries that sum edge values on a path; process M operations online.	Hard8	TreeSegment tree+2	No attempts yet	1s	128 MB	Judgeable
Cow Beauty PageantGiven a grid with exactly three connected X-spots, find the fewest empty cells to paint so the three spots merge into one connected region.	Hard8	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Buying FeedBuy at least K pounds of feed from stores along a 1D route, paying purchase cost plus K^2 cents per mile for the load carried, and minimize the total.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
CandyGiven starting candies, allowed daily eating amounts, and favorite numbers that trigger bonus candies, maximize total candies eaten or report -1 if infinite.	Hard8	Dynamic programmingGraph+2	No attempts yet	1s	128 MB	Judgeable
The Continental CowngressEach of M cows casts yes/no votes on two distinct bills, and every cow must win at least one vote; decide for each bill whether it passes in all valid outcomes, fails in all, or varies.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Roads and PlanesFind shortest paths from town S in a graph mixing bidirectional non-negative roads with one-way planes that may have negative costs and never form a return cycle.	Hard8	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
The Lost CowsGiven a synchronizing automaton over N states with M shared input letters, compute the maximum over all pairs of the shortest synchronizing word length for that pair.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
The TriangleGiven a triangular grid of values, find the sub-triangle (either orientation, side at least K) whose truncated average is largest.	Hard8	Binary searchPrefix sum+2	No attempts yet	2s	128 MB	Judgeable
Cow TreatsSimulate a greedy process on a W by H grid where rows and columns may be swapped to place the highest remaining value in the earliest reachable slot.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
AllowanceGiven coin denominations where each divides the next and bounded supplies, find the maximum number of weeks you can pay at least C each week.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Who Brings the Cookies?Assign one cookie-bringing cow per study group so each cow's meeting count stays within a ceiling-of-reciprocals limit, choosing the lexicographically smallest assignment.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
LightsEach switch toggles a light and its neighbors; find the minimum number of switches to press so that all N lights end up on.	Hard8	Bit manipulationMath+2	No attempts yet	1s	128 MB	Judgeable
Coin GameTwo players alternately take coins from the top of a pile, where each move may take between 1 and twice the previous move's count; find the maximum total value the first player can guarantee with optimal play from both sides.	Hard8	Dynamic programmingGame theory+2	No attempts yet	1s	32 MB	Judgeable
Cow Toll PathsFor each query, find the cheapest s-t trip where cost is the sum of edge tolls plus the single largest pasture toll on the route. N=250, K=10000.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Shipping Around an IslandFind the shortest closed loop of grid cells that encloses the main island of A cells but encloses no x cell, where paths may revisit cells.	Hard8	BFSShortest path+2	No attempts yet	1s	128 MB	Judgeable
Cow TelephonesGiven a tree with cows at its leaves and vertex capacity K plus unit edge capacity, find the maximum number of disjoint leaf-to-leaf conversation paths.	Hard8	TreeDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
Barn AllocationGiven stall capacities and interval requests, find the maximum number of requests that can be granted without any stall exceeding its capacity.	Hard8	GreedySegment tree+2	No attempts yet	2s	128 MB	Judgeable
StarCowraftGiven test battle outcomes and the constraint that no unit strength exceeds 100 times another, determine for each new battle whether one army must win or the result is undecidable.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Test TakingGiven N questions and a set of possible true-counts, choose a true/false answer key maximizing the worst-case number of correct answers.	Hard8	MathGreedy+2	No attempts yet	1s	128 MB	Judgeable
Rocks and TreesRocks sit on the non-root nodes of a rooted tree; players alternately push up to L rocks from a node to its parent, and after each point update you decide if the first player wins.	Hard8	Game theoryTree+2	No attempts yet	1s	128 MB	Judgeable
Water SlidesOn a DAG where each node leading to the sink, Bessie maximizes her worst-case path sum when up to K times she is forced down the worst outgoing edge.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Triangle CountingCount how many triangles formed by triples of N integer points strictly contain the origin in their interior.	Hard8	GeometrySorting+2	No attempts yet	1s	128 MB	Judgeable
Holedox MovingFind the minimum number of moves for a snake of length up to 8 to slide its head to the exit at (1,1) on a grid with stones, where the tail cell counts as blocked during a move.	Hard8	BFSSimulation+2	No attempts yet	1s	128 MB	Judgeable
Game PredictionGiven your n distinct cards in an m-player game where every card from 1 to n*m is dealt, find the most rounds you can guarantee to win against any opponent play.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Winning CheckersFind the lexicographically smallest sequence of diagonal jumps by which a single king captures every opponent checker on an N x N board, or report that none exists.	Hard8	DFSBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Jigsaw PuzzlesPlace every piece into an R by C grid, rotating but not flipping, so touching edges match and the outer boundary is all borders; print the lexicographically smallest assembly.	Hard8	BacktrackingBrute force+2	No attempts yet	1s	128 MB	Judgeable
CheckersOn an N x N board, decide whether one king can capture every opponent checker in a single move of consecutive diagonal jumps, and print the unique landing sequence if so.	Hard8	DFSBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Earthquake DamageGiven a graph and reports that certain damaged pastures cannot reach the barn, find the minimum total number of pastures that cannot return to the barn.	Hard8	GraphUnion-find+2	No attempts yet	1s	128 MB	Judgeable
Safe TravelFor each pasture i, find the shortest path from pasture 1 to i that avoids the last edge of the unique shortest path to i.	Hard8	GraphShortest path+1	No attempts yet	3s	128 MB	Judgeable
Pink FloydGiven the all-pairs shortest-distance matrix of a weighted tree, reconstruct any tree that produces these distances and print its adjacency list.	Hard8	TreeGraph+2	No attempts yet	1s	128 MB	Judgeable
Surround the Islands with FenceGiven N edges that form disjoint polygon islands and a symmetric vertex-to-vertex boat cost matrix, find the minimum total cost of round trips needed to fence every island, starting anywhere.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
ExamsCount subsets of at most 36 positive exam scores whose sum is at least T, where each score can be as large as 10^13.	Hard8	Bit manipulationBinary search+2	No attempts yet	1s	128 MB	Judgeable
Earthquake Damage 2Given an undirected graph and a set of vertices that cannot reach the barn, find the minimum number of other vertices to remove so that exactly those vertices are separated from vertex 1.	Hard8	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
PaybackFriends stand at positions 1 to N with signed debts; Bessie starts at 0 holding nothing, must never go negative, and finishes at N. Find the minimum walking distance to settle all accounts.	Hard8	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
Holiday PaintingPaint rectangle updates on an R x C grid, R up to 50000 and C up to 15, and after each of Q updates report how many cells equal a fixed target pattern.	Hard8	Segment treeBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Telephone LineRaise each pole to height at least its original, paying squared increase plus C times adjacent height gaps, and minimize the total.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Sightseeing CowsFind a directed cycle maximizing the ratio of total fun at its first-visit landmarks to total traversal time, and print that maximum ratio.	Hard8	GraphBinary search+2	No attempts yet	1s	128 MB	Judgeable
TreasureGiven a connected graph with N nodes and N edges and max degree 4, count the distinct rooted versions of the graph up to isomorphism, where each root is a non-4-degree node.	Hard8	GraphTrie+2	No attempts yet	1s	128 MB	Judgeable
Haybale GuessingGiven interval minimum queries with distinct values, find the earliest query that makes the whole set of answers inconsistent.	Hard8	Binary searchSorting+2	No attempts yet	1s	128 MB	Judgeable
Artificial LakeWater fills a terrain of N distinct-height platforms at 1 unit per minute; report when each platform first has 1 unit of water above it.	Hard8	StackSimulation+2	No attempts yet	1s	128 MB	Judgeable
HotelProcess check-in and check-out requests on a row of hotel rooms, always assigning the leftmost block of the requested length, or 0 if none fits.	Hard8	Segment treeDivide and conquer+1	No attempts yet	1s	128 MB	Judgeable
Grabbing LandSplit N rectangles into groups, each group costing the product of its max width and max height, minimizing the total cost.	Hard8	SortingDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Flood FillGiven M points and a threshold D, group points whose taxicab distance is at most D into connected components, then report the number of components and the largest component size.	Hard8	Union-findSorting+2	No attempts yet	2s	128 MB	Judgeable
Milk PatternsGiven N integers, find the length of the longest contiguous subsequence that repeats at least K times, counting overlapping occurrences.	Hard8	String matchingBinary search+2	No attempts yet	1s	128 MB	Judgeable
Silver Lilypad PondOn a grid with knight moves, place the fewest new lilypads so the cow can travel from start to goal, then count the shortest such paths.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Fire Evacuation PlanGiven a grid with walls, flowers, people, and one exit, find the minimum time for everyone to reach the exit, where no two people may occupy the same cell at the same second.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable