Problems

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Total results29,429 problems

Freight Train
Hard8
Intervals, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Fence Escape Season IV
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Shark Dinner
Hard8
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Feeding the Panda
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Marble Slabs
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Card Flipping
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Highway
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cups
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Right Triangles
Hard8
Geometry, Math+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Race Bib Numbers
Hard8
Union-find, Graph+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Traffic System
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alleyways
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Road Direction Planning
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Dividing Classes
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hide
Hard8
Shortest path, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Exact-Trail Relay
Hard8
Shortest path, Matrix+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
The Kindest Dasom
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Kangho the Part-Time Worker
Hard8
Greedy, Heap+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
N-Rook
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tree Coloring
Hard8
Greedy, Tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
N-Rook II
Hard8
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Surprise Gift Delivery
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Palindrome Encoding
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Banknotes for a New Game
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Martial Arts Practice
Hard8
Graph, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Food Wrap Area
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Log Transport
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tree Height Reduction
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Broadcast Network
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Distances
Hard8
Geometry, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Building a Tree Model
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Military Deployment
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Winning Moves in a Pawn Game
Hard8
Game theory, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cave Exploration
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximum Volume from Orthogonal Projections
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Two Points with the Greatest Slope
Hard8
Divide and conquer, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Grade
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Spiderweb
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hexagons
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Roof Construction
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Balance Scale
Hard8
Tree, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shy Polygon Placement
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Prison Break
Hard8
Binary search, BFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Students' Study Styles
Hard8
Brute force, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cave Lamp
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Product Expansion Length
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Avoiding the Smell
Hard8
Binary search, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Counting Product Subset Coefficients
Hard8
Number theory, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Clone Robot
Hard8
Shortest path, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
High Spies
Hard8
Tree, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bus Routes
Hard8
Combinatorics, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hotel Reservation
Hard8
Greedy, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Box
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Nap Time
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Closed-Circuit Surveillance
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bowl Stacking
Hard8
Geometry, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polygon Count
Hard8
Geometry, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Partial DNA Substrings
Hard8
String matching, Binary search+1
No attempts yet
Time limit
2s
Memory limit
16 MB
Judgeable
Knight Tour
Hard8
Backtracking, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Picnic
Hard8
Backtracking, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Burger King
Hard8
Simulation, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pyramid
Hard8
Prefix sum, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Grid Filling
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number Pairing
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maze
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hello, 2048!
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tile Game
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Half-Rays
Hard8
Divide and conquer, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Task Order
Hard8
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bicycle Race
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Visible Mountain Range
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minimum Power Operations
Hard8
BFS, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cheap but Similar
Hard8
Greedy, Dynamic programming+1
No attempts yet
Time limit
7s
Memory limit
16 MB
Judgeable
Sum of Fibonacci Numbers
Hard8
Math, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number of Trees
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tickets
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Surveillance Robot
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tailed Sungwon Monkeys
Hard8
Union-find, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Zoo Enclosure Visibility
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Programming Language L
Hard8
Simulation, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Playing in Threes
Hard8
Hash map, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Six People in a Circle
Hard8
Graph, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Block Stacking
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cloth Moth Shortest Path
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Earthquake Recovery
Hard8
Minimum spanning tree, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Compressing a String
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Closest Reduced Fraction
Hard8
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minesweeper
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Jumping Fences
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Arranging Seats
Hard8
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Planning a Trip
Hard8
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tennis Match
Hard8
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Perimeter of a Rectangle Union
Hard8
Sorting, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Two Sequences
Hard8
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Polynomial Calculator
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Dividing Election Districts
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bus Terminal
Hard8
Greedy, Geometry+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Heap Sort With the Maximum Number of Swaps
Hard8
Heap, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Building Prison Walls
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Nuclear Bomb
Hard8
Geometry, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Freight TrainGiven two trains as unions of intervals of occupied cars, find the smallest forward shift of one train that maximizes the count of aligned occupied cars.	Hard8	IntervalsMath+2	No attempts yet	2s	128 MB	Judgeable
Fence Escape Season IVGiven N horizontal fence segments Jimin must dodge by sidestepping to their endpoints, compute the minimum total horizontal movement to reach the exit below.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Shark DinnerGiven each shark's size, speed and intelligence, model who can eat whom (at most two meals, at most one death each) as a flow network and find the minimum number of survivors.	Hard8	GraphBFS+1	No attempts yet	2s	128 MB	Judgeable
Feeding the PandaFind the longest sequence of bamboo groves with strictly increasing tastiness where consecutive Manhattan distance stays within the destination's bamboo count.	Hard8	Dynamic programmingGeometry+2	No attempts yet	2s	128 MB	Judgeable
Marble SlabsFind the minimum wasted area when guillotine-cutting a rectangular slab into a set of allowed non-rotatable rectangle sizes.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	2s	128 MB	Judgeable
Card FlippingGiven an R by 16 grid of target flip states, find the minimum number of contiguous row or column flip operations to turn all cards from face up to the required pattern.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	5s	128 MB	Judgeable
HighwayGiven an undirected graph where each road has a toll and a travel time, count the distinct Pareto-optimal (toll, time) pairs achievable by routes between two given cities.	Hard8	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
CupsGiven two transition functions over N cups, find an A/B move string of length at most 10000 that sends a ball to cup 1 regardless of its starting cup.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Right TrianglesGiven up to 1500 distinct 2D points, count how many of the triangles formed by choosing three points are right triangles.	Hard8	GeometryMath+2	No attempts yet	5s	256 MB	Judgeable
Race Bib NumbersGiven N T-shirts each printed with two candidate bib numbers, choose one number per shirt so all visible numbers are distinct, or print -1 if no such choice exists.	Hard8	Union-findGraph+2	No attempts yet	3s	512 MB	Judgeable
Traffic SystemGiven a connected graph of cities and roads, answer many queries asking if two cities stay connected after deleting one specific road or all roads of a chosen city.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
AlleywaysFind the maximum-value path from node 1 to node n in a directed weighted graph, or report -1 if the value can grow without bound due to a positive cycle on a valid path.	Hard8	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
Road Direction PlanningDecide if directions for N horizontal and M vertical one-way roads can be chosen so every bus route still has a shortest path using at most one horizontal and one vertical road.	Hard8	GraphDFS+2	No attempts yet	2s	128 MB	Judgeable
Dividing ClassesGiven n students and m pairs who know each other's messenger ID, split them into the maximum number of classes so that any two students in different classes know each other, then output the class sizes.	Hard8	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
HideGiven room capacities and travel times between rooms, find the minimum time bound so that excess students can be relocated without any room exceeding its limit, using shortest paths and a feasibility check.	Hard8	Shortest pathBinary search+2	No attempts yet	2s	128 MB	Judgeable
Exact-Trail RelayCompute the minimum total length of a walk between two intersections that uses exactly N trails, where N can be as large as one million.	Hard8	Shortest pathMatrix+2	No attempts yet	2s	128 MB	Judgeable
The Kindest DasomGiven grid coordinates of footprints, find the maximum number of points that lie on one straight line with equal spacing between consecutive points.	Hard8	GeometryMath+2	No attempts yet	2s	64 MB	Judgeable
Kangho the Part-Time WorkerGiven N customers each with a planned tip, choose the serving order to maximize the total tip after subtracting (position-1) from each tip and clipping negative values to zero.	Hard8	GreedyHeap+2	No attempts yet	2s	256 MB	Judgeable
N-RookGiven a grid with walls blocking line of sight and pit cells that block placement but not sight, find the maximum number of mutually non-attacking rooks.	Hard8	GraphDFS+2	No attempts yet	2s	128 MB	Judgeable
Tree ColoringGiven a rooted tree with node weights, find the minimum total cost of coloring all nodes in an order that respects parent-before-child, where each node's cost is weight times its coloring position.	Hard8	GreedyTree+2	No attempts yet	2s	128 MB	Judgeable
N-Rook IICount placements of K rooks on an N by M board so each rook is attacked by at most one other rook, modulo 1,000,001.	Hard8	CombinatoricsMath	No attempts yet	2s	128 MB	Judgeable
Surprise Gift DeliveryGiven N delivery points on a line from a warehouse, find the minimum cost combining limited-capacity truck trips, per-stop parking fees, and one-at-a-time walking deliveries to drop a gift at every point.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Palindrome EncodingGiven a binary string, repeatedly delete the second half of any even-length palindromic substring and find the minimum length achievable.	Hard8	Dynamic programmingString+2	No attempts yet	2s	128 MB	Judgeable
Banknotes for a New GameChoose K denominations starting at 1 won where each next one is 2, 3, 4, or 5 times the previous, to minimize the number of banknotes summing to N won.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	128 MB	Judgeable
Martial Arts PracticeGiven who each student in two facing rows aims at, assign bow or shield to everyone so bows only target shields and every shield is targeted by some bow.	Hard8	GraphTopological sort+2	No attempts yet	2s	128 MB	Judgeable
Food Wrap AreaGiven N food items on a 2-row by B-column grid, cover every food cell using at most K axis-aligned rectangular wraps while minimizing the total wrap area.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Log TransportGiven a tree of villages flowing into a kingdom, choose k extra sawmill locations to minimize the total weight times distance cost of routing each village's logs to its nearest downstream mill.	Hard8	Dynamic programmingTree+2	No attempts yet	2s	128 MB	Judgeable
Tree Height ReductionGiven a rooted tree and target height H, find the minimum total cost of repeatedly reattaching vertices to ancestors (cost based on level gap) to bring the tree height down to at most H.	Hard8	TreeDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Broadcast NetworkPick which edges of a rooted tree to install so that total user fees minus installation cost stays non-negative while maximizing the number of served users, solved with tree knapsack DP.	Hard8	Dynamic programmingTree+2	No attempts yet	2s	128 MB	Judgeable
DistancesGiven up to 100,000 planar points, compute the farthest and closest pair distances under Euclidean (squared), Manhattan, and Chebyshev metrics.	Hard8	GeometryDivide and conquer+2	No attempts yet	1s	256 MB	Judgeable
Building a Tree ModelGiven a tree, find the minimum number of non-branching path segments (strings) needed to cover every edge exactly once, then minimize the length of the longest such string.	Hard8	TreeDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Military DeploymentPlace at most G soldiers on roads between villages and two cities to block every path between the cities, minimizing the larger of the two cities' worst soldier return times.	Hard8	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
Winning Moves in a Pawn GameGiven n pawns on a 1..m board where cell m is empty and a move slides a pawn to the nearest empty cell right of it, count moves that lead to a forced win under combinatorial game theory.	Hard8	Game theoryCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Cave ExplorationFind the minimum-time simple cycle through room 1 in a directed graph built from asymmetric tunnel costs, using no room or tunnel twice.	Hard8	GraphShortest path+1	No attempts yet	1s	256 MB	Judgeable
Maximum Volume from Orthogonal ProjectionsGiven two convex polygon projections of a 3D solid onto the xz and yz planes, compute the maximum possible volume of a convex solid consistent with both.	Hard8	GeometryMath+2	No attempts yet	2s	128 MB	Judgeable
Two Points with the Greatest SlopeGiven N points with distinct x and y coordinates, find the pair whose line has the largest absolute slope, breaking ties by smallest indices.	Hard8	Divide and conquerGeometry+2	No attempts yet	2s	128 MB	Judgeable
GradeGiven N exam score/total pairs, find every count D of excluded exams for which some other exclusion beats removing the D lowest-percentage exams.	Hard8	Binary searchGreedy+2	No attempts yet	2s	128 MB	Judgeable
SpiderwebGiven a convex polygon's vertices and circular puddles, find the maximum number of non-crossing diagonals that avoid all puddles.	Hard8	Dynamic programmingGeometry+2	No attempts yet	2s	128 MB	Judgeable
HexagonsGiven up to 80 stick lengths, count distinct equiangular hexagons formed by picking six sticks, treating rotations and reflections as the same shape.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Roof ConstructionGiven N points and a limit K, find the minimum vertical offset needed so a concave polyline with at most K segments lies on or above every point.	Hard8	GeometryBinary search+2	No attempts yet	2s	128 MB	Judgeable
Balance ScalePlace weights 1..n into two mirror-shaped binary trees filled level by level under BST-like ordering rules so both sides balance in total weight, or report impossible.	Hard8	TreeSimulation+2	No attempts yet	1s	512 MB	Judgeable
Shy Polygon PlacementGiven two polygons that can only slide horizontally, find the minimum bounding strip width so that every pair of points from the two polygons stays at least L apart.	Hard8	GeometryBinary search+1	No attempts yet	2s	128 MB	Judgeable
Prison BreakGiven a grid prison with walls, empty cells (each holding one person), and exits that admit one escapee per second, find the minimum time for everyone to leave or report impossibility.	Hard8	Binary searchBFS+1	No attempts yet	2s	128 MB	Judgeable
Students' Study StylesGiven statements from students of four truthfulness types depending on day or night, determine which facts about identities and time must hold in every consistent scenario.	Hard8	Brute forceImplementation+1	No attempts yet	2s	128 MB	Judgeable
Cave LampGiven a polyline cave floor, find the minimum y-coordinate at which a lamp above the floor can see every point of the floor without the visibility line being blocked by the terrain.	Hard8	Binary searchGeometry+1	No attempts yet	2s	128 MB	Judgeable
Product Expansion LengthCompute, modulo 10000, the exact printed character length of the fully expanded symbolic expansion of the product (x+a1)...(x+an) for n up to 1e9.	Hard8	MathCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Avoiding the SmellFind a grid path from start to destination that maximizes the minimum Euclidean distance to any of several marked smelly points, and output the square of that optimal distance.	Hard8	Binary searchBFS+2	No attempts yet	2s	128 MB	Judgeable
Counting Product Subset CoefficientsGiven huge n (up to 500+ digits) and a prime p, count how many k in [0,n] make the elementary symmetric sum f(n,k) not divisible by p, output the count mod 1e9+7.	Hard8	Number theoryCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Clone RobotGiven a maze with a start and up to 250 keys, minimize the total moves of self-cloning robots (splitting only at start/key cells) needed to collect every key.	Hard8	Shortest pathMinimum spanning tree+2	No attempts yet	2s	128 MB	Judgeable
High SpiesGiven a tree of ports with observed directed edge flows, compute the minimum and maximum containers that could have traveled between two leaf countries, respecting the no-immediate-return constraint at each port.	Hard8	TreeGreedy+2	No attempts yet	2s	128 MB	Judgeable
Bus RoutesGiven a multiset of arrival minutes within a 60-minute window, reconstruct the minimum number of arithmetic-progression bus routes (each appearing at least twice) that exactly explain the multiset.	Hard8	CombinatoricsGreedy+2	No attempts yet	2s	128 MB	Judgeable
Hotel ReservationAssign men, women, and married couples to rooms with capacity/cost constraints under strict cohabitation rules, minimizing total rental cost or reporting impossibility.	Hard8	GreedyDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Number BoxGiven two rows of tiles that can slide within their row preserving order, find the arrangement maximizing the sum of column-wise products.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Nap TimePick exactly B of N intervals arranged in a circle, maximizing sum of chosen values where the first interval of each consecutive block scores zero.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Closed-Circuit SurveillanceGiven a convex polygon and a set of candidate exterior camera points with costs, find the minimum total cost of camera placements so every polygon edge is visible (strictly, not collinear) from at least one chosen camera, or report -1 if impossible.	Hard8	GeometryGreedy+1	No attempts yet	2s	128 MB	Judgeable
Bowl StackingGiven n frustum-shaped bowls, find the stacking order that minimizes total stack height, using geometric overlap calculations, then output the floor of the minimum height.	Hard8	GeometryBrute force+1	No attempts yet	1s	128 MB	Judgeable
Polygon CountGiven up to 60 integer-coordinate segments drawn on paper, count how many simple closed polygons are formed, excluding faces from crossings and shapes touched by dangling extra edges.	Hard8	GeometryGraph+1	No attempts yet	2s	128 MB	Judgeable
Partial DNA SubstringsGiven a DNA string, count distinct substrings occurring at least m times and find the K-th one under length-then-lex order.	Hard8	String matchingBinary search+1	No attempts yet	2s	16 MB	Judgeable
Knight TourConstruct a full knight's tour on an N by N board (N up to 666) starting from a given square, using Warnsdorff-style or divide-and-conquer construction, or report impossibility.	Hard8	BacktrackingDivide and conquer+1	No attempts yet	1s	128 MB	Judgeable
PicnicFind the lexicographically smallest clique of exactly K students among N students given F friendship edges, or report -1 if none exists.	Hard8	BacktrackingGraph+1	No attempts yet	2s	128 MB	Judgeable
Burger KingSimulate multiple restaurant queues with dynamic employee replacements and arrivals, tracking the optimal switching strategy to find when the team can order.	Hard8	SimulationGreedy+1	No attempts yet	2s	128 MB	Judgeable
PyramidFind placement of an a×b pyramid and interior c×d room on a height grid maximizing the average height of pyramid cells excluding the room, requiring 2D prefix sums and sliding min-window optimization.	Hard8	Prefix sumSliding window+2	No attempts yet	2s	128 MB	Judgeable
Number Grid FillingConstruct an N by M grid so that absolute differences of all adjacent cell pairs form exactly the set 1..2NM-N-M with each value used once.	Hard8	MathCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Number PairingPair adjacent grid cells whose value difference is at most T to maximize total pairing weight, which requires a general weighted matching approach exploiting the grid's bipartite structure.	Hard8	GraphDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
MazeGiven a tree-like maze grid, compute the expected number of steps for a random depth-first exploration (choosing unvisited branches uniformly, backtracking on dead ends) to travel from entrance to exit.	Hard8	TreeDFS+2	No attempts yet	2s	128 MB	Judgeable
Hello, 2048!Given l and r, find how many times the number formed by concatenating 2^l through 2^r in decimal divides evenly by 2, without building the huge number.	Hard8	MathNumber theory+1	No attempts yet	1s	512 MB	Judgeable
Tile GameGiven colored numbered tiles, compute the maximum score obtainable by repeatedly removing groups of at least three tiles that form a same-color numeric run or a same-number all-different-color set.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
Half-RaysGiven N half-rays defined by lines restricted to x>0, answer online queries with forced XOR decoding that ask for the maximum x-coordinate where a query line intersects any half-ray, using a Li Chao-style convex hull technique.	Hard8	Divide and conquerBinary search+2	No attempts yet	2s	128 MB	Judgeable
Task OrderGiven a tournament-like directed graph on N tasks where every pair has at least one direction, partition all tasks into the minimum number of directed paths covering each node once.	Hard8	GraphGreedy+1	No attempts yet	2s	128 MB	Judgeable
Bicycle RaceGiven N riders each with energy E and a race of D laps, find the minimum integer number of minutes to finish, rotating who leads to share energy costs optimally.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Visible Mountain RangeCompute the total visible area of overlapping isosceles triangular mountains that share a common baseline, given up to 100,000 triangles.	Hard8	GeometrySorting+1	No attempts yet	2s	128 MB	Judgeable
Minimum Power OperationsGiven P up to 20000, find the minimum number of multiply or divide operations using only two variables to reach x^P from x and 1.	Hard8	BFSDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Cheap but SimilarGiven a mineral row, decide whether equipment covering 1-3 consecutive cells can be placed to mine at least 75% of the total, and construct a valid placement if so.	Hard8	GreedyDynamic programming+1	No attempts yet	7s	16 MB	Judgeable
Sum of Fibonacci NumbersCompute the sum of Fibonacci numbers between two indices up to 9x10^18, modulo 1e9, requiring matrix exponentiation with modular arithmetic.	Hard8	MathMatrix+1	No attempts yet	2s	128 MB	Judgeable
Number of TreesCount the number of rooted ordered trees whose DFS-with-repeated-parent-writes traversal string equals a given string, modulo 1e9.	Hard8	Dynamic programmingString+1	No attempts yet	2s	128 MB	Judgeable
TicketsAssign seat blocks of length L to families to maximize profit, where exact preferred block gives 2, any other free block of L seats gives 1, and blocks can't overlap.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Surveillance RobotDetermine every x-axis interval where a robot could stand so that the angular sweep order of chimneys matches a given observed shape sequence.	Hard8	GeometrySorting+1	No attempts yet	2s	128 MB	Judgeable
Tailed Sungwon MonkeysGiven a tree-like hand-connection graph of monkeys that loses edges over time, determine for each monkey the exact removal step when it becomes disconnected from monkey 1, essentially offline dynamic connectivity via reverse union-find.	Hard8	Union-findGraph+1	No attempts yet	2s	128 MB	Judgeable
Zoo Enclosure VisibilityGiven an orthogonal polygon and one designated wall, compute the perimeter of the kernel region visible from every point of that wall.	Hard8	GeometryImplementation+1	No attempts yet	2s	128 MB	Judgeable
Programming Language LSimulate execution of a custom esoteric language with nested loops and conditional jumps to find the maximum number of printed line executions, capping at infinity beyond 1e9.	Hard8	SimulationDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Playing in ThreesGiven N points and fixed integer side lengths A, B, C for a right triangle, count triples of points forming exactly that right triangle.	Hard8	Hash mapGeometry+1	No attempts yet	2s	128 MB	Judgeable
Six People in a CircleGiven N people and an acquaintance graph, count the number of distinct 6-cycles (arrangements around a circle up to rotation and reflection) modulo 9901.	Hard8	GraphCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Block StackingCount A by B height-grids with heights 0 to C that are non-increasing along both rows and columns, modulo 1e18.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Cloth Moth Shortest PathCompute the shortest path for a point moving on an infinite plane while avoiding the interiors of possibly overlapping convex polygons, allowed to travel along their boundaries.	Hard8	GeometryShortest path+1	No attempts yet	2s	128 MB	Judgeable
Earthquake RecoveryGiven a graph with edge costs and times, choose a spanning tree maximizing (F minus total cost) divided by total time, requiring fractional binary search combined with MST computation.	Hard8	Minimum spanning treeBinary search+2	No attempts yet	2s	128 MB	Judgeable
Compressing a StringFind the minimum length of a string obtained by optimally applying nested k(S) run-length style compression to a given lowercase string of length up to 200.	Hard8	Dynamic programmingString+1	No attempts yet	2s	128 MB	Judgeable
Closest Reduced FractionGiven a reduced fraction with numerator and denominator up to 32767, find the closest distinct reduced fraction within those bounds, breaking ties by smaller value.	Hard8	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
MinesweeperGiven a Minesweeper board where only border cells are revealed with numbers, determine the maximum number of mines that can be placed in the closed interior cells consistently with the border clues.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Jumping FencesFind a closed walk from a start point visiting exactly K points that maximizes the product of fence-jumping success probabilities over all moves, given fences that block segments between points.	Hard8	GraphDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Arranging SeatsGiven seat positions with scores, compute the minimum cost to rearrange computers (with a lift/place cost and per-step carrying cost for up to two items) so the row becomes a rotation of the sorted score sequence.	Hard8	GreedyMath+1	No attempts yet	2s	128 MB	Judgeable
Planning a TripGiven a directed graph, find the maximum number of distinct cities visitable on a walk from S to T, allowing revisits of cities and edges.	Hard8	GraphDFS+1	No attempts yet	2s	128 MB	Judgeable
Tennis MatchSimulate a multi-player variant of tennis with custom scoring, serving rotation, and set/match rules to determine the overall winner from a sequence of game winners.	Hard8	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
Perimeter of a Rectangle UnionCompute the total outer perimeter of the union of up to 5000 axis-aligned rectangles using a sweep-line approach.	Hard8	SortingGeometry+1	No attempts yet	2s	128 MB	Judgeable
Two SequencesPartition two sequences from the back into matched groups to minimize the total sum of products of adjusted group sums, requiring an optimized DP over prefix sums.	Hard8	Dynamic programmingPrefix sum+1	No attempts yet	2s	128 MB	Judgeable
Polynomial CalculatorFind the minimum number of key presses to build a given monic polynomial using a calculator that applies operations sequentially without memory.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Dividing Election DistrictsPartition 3K cities into three groups of K cities each so that at least two groups have total supporters exceeding 500K, given a guaranteed feasible instance.	Hard8	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
Bus TerminalGiven N grid points, pick two hub points and assign every other point to one hub so that the maximum pairwise routing distance through the hubs is minimized.	Hard8	GreedyGeometry+1	No attempts yet	5s	128 MB	Judgeable
Heap Sort With the Maximum Number of SwapsConstruct a max-heap of 1..n as an array that maximizes the total number of swaps performed by repeated heap-sort deletions.	Hard8	HeapGreedy+1	No attempts yet	2s	128 MB	Judgeable
Building Prison WallsGiven a prison point and N surrounding posts, determine the maximum number of nested, non-touching polygon layers (each vertex a post, minimum size 3) fully enclosing the prison that can be formed.	Hard8	GeometryGreedy+1	No attempts yet	2s	128 MB	Judgeable
Nuclear BombSelect a subset of given segments forming a convex polygon that encloses a fixed point, minimizing total cost, or report impossibility.	Hard8	GeometryGraph+1	No attempts yet	2s	128 MB	Judgeable