Problems

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Total results29,425 problems

Infected Land
Hard8
BFS, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stopped Watches
Hard8
Brute force, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Digits on the Floor
Hard8
Graph, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Keyword Search
Hard8
String matching, Bit manipulation+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
City Road Map
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
20s
Memory limit
128 MB
Judgeable
Colored Cube 8-Puzzle
Hard8
BFS, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Manhattan Wiring
Hard8
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Organize Your Train
Hard8
BFS, Simulation+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Mobile Computing
Hard8
Recursion, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shy Polygon
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Inherit the Spheres
Hard8
Union-find, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mad Veterinarian
Hard8
BFS, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Push-To Telescope
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Track Smoothing
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Treasure Diving
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Magical Crafting
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Epidemic Flu
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Caravan Robbers
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Disjoint Regular Expressions
Hard8
Dynamic programming, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Snake Cube
Hard8
Backtracking, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Great Trickster
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kingdom Reunion
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ninja Assignment
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Kunai
Hard8
Geometry, Hash map+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Finding a Path
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Guess My Word
Hard8
Game theory, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Commando
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Patrol
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Signal
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Digging for Oil
Hard8
Prefix sum, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
ATM
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hexagon Perplexagon
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Have You Driven a Fjord Lately?
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Target Practice
Hard8
Geometry, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stake Your Claim
Hard8
Game theory, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Reliable Nets
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Square Count
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hexagram
Hard8
Brute force, Backtracking+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Billiard Table
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Teleport Out!
Hard8
Dynamic programming, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Worms
Hard8
Dynamic programming, Intervals+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Triangle War
Hard8
Game theory, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Paper Route
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Recovering the Common Ratio of a Geometric Sequence
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Harmonious Matrices
Hard8
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
New Horizons
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Divorce
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
30s
Memory limit
128 MB
Judgeable
Stack Machine
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pipes
Hard8
Backtracking, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Meltdown
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stake Coordinate Reconstruction
Hard8
Graph, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Moveable Maze
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rotate to Root
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Laurel Creek
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rocket Stages
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bus Driver Seungjae
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Fibonacci Word
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Infiltration
Hard8
Graph, Greedy+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Keys
Hard8
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Robot Vacuum
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Safe Company
Hard8
Simulation, Implementation+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Takeover Wars
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Secret Project
Hard8
BFS, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chip Design
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Coffee Shops
Hard8
Prefix sum, Geometry+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Machine Works
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Magic Sticks
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Mining Your Own Business
Hard8
Graph, DFS+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Pyramids
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Gangs
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Carpool
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Moonshine
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Medals
Hard8
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Structural Equivalence
Hard8
Union-find, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Magic Bitstrings
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Brownie Points II
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Great Circle
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Treequivalence
Hard8
Tree, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Treasure Map
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Advanced Causal Measurements (ACM)
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Brief Gerrymander
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Intellectual Property
Hard8
String matching, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Temple of Dune
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Catenyms
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jogging Trails
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Return of the Jedi
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Discrete Logarithm
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Snow Clearing
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bounding Box
Hard8
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Subway
Hard8
Math, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hotter Colder
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Language Cardinality
Hard8
String, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tail Palindrome
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maze Escape
Hard8
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Boastin' Red Socks
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spaghetti
Hard8
Graph, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Crypt Kicker
Hard8
Backtracking, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Leaps Tall Buildings (in a Single Bound)
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ritual Circle
Hard8
Geometry, Brute force+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Saruman's Level Up
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Infected LandFind the shortest sequence of vehicle moves that fully disinfects a grid governed by Conway-like infection rules with a protective moving vehicle, using BFS over cellular automaton states.	Hard8	BFSSimulation+1	No attempts yet	1s	128 MB	Judgeable
Stopped WatchesGiven ambiguous watch hand readings under rotation and permutation, find the shortest time interval containing at least one valid candidate time for every watch.	Hard8	Brute forceSimulation+2	No attempts yet	1s	128 MB	Judgeable
Digits on the FloorGiven bar segments on a plane, reconstruct their connection graph with signed right-angle joints and count how many of each seven-segment-style digit shape (0-9) appears, ignoring shapes nested inside larger ones.	Hard8	GraphGeometry+2	No attempts yet	2s	128 MB	Judgeable
Keyword SearchGiven up to 12 base strings, count positions in a text where some permutation-concatenation of all base strings occurs as a substring, treating duplicate resulting strings once.	Hard8	String matchingBit manipulation+2	No attempts yet	10s	128 MB	Judgeable
City Road MapBuild a graph from road segments with one-way restrictions imposed by perpendicular or angled sign segments, then find the unique shortest path between two points.	Hard8	Shortest pathGraph+2	No attempts yet	20s	128 MB	Judgeable
Colored Cube 8-PuzzleFind the minimum number of die-rolling moves (capped at 30, else -1) to reach a target arrangement of colored dice and blank cell on a 3x3 board, via state-space search.	Hard8	BFSSimulation+1	No attempts yet	1s	128 MB	Judgeable
Manhattan WiringFind two vertex-disjoint shortest simple paths on a small grid connecting two pairs of marked cells while avoiding obstacles, minimizing total path length or returning 0 if impossible.	Hard8	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
Organize Your TrainGiven a small rail-yard graph with parking lines and exchange links, compute the minimum number of sub-train moves to transform an initial arrangement of typed cars into a target arrangement.	Hard8	BFSSimulation+2	No attempts yet	3s	128 MB	Judgeable
Mobile ComputingBuild every possible binary mobile from given stone weights and pick the widest one whose width is strictly less than a given room width, output as reduced fraction.	Hard8	RecursionBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Shy PolygonGiven two simple polygons that can be slid only along the x-axis, find the minimum total x-extent such that every point of one polygon stays at least distance L from every point of the other.	Hard8	GeometryBinary search+1	No attempts yet	2s	128 MB	Judgeable
Inherit the SpheresSimulate a horizontal plane sweeping through overlapping spheres and output the exact sequence of increases and decreases in the number of connected disc components using event-based union-find at critical z-values.	Hard8	Union-findGeometry+1	No attempts yet	1s	128 MB	Judgeable
Mad VeterinarianGiven three reversible machines that each turn one animal of a species into a multiset of animals, find the minimum number of applications that turns the start counts into the target counts.	Hard8	BFSNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Push-To TelescopeCompute azimuth and elevation of catalogue stars from two setup readings, using a rotating equatorial frame, and print them or NOT VISIBLE.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Track SmoothingGiven a convex polygon and minimum corner radius r, find the scale factor s so the inner-scaled offset track has the same perimeter as the original.	Hard8	GeometryBinary search+2	No attempts yet	2s	128 MB	Judgeable
Treasure DivingGiven a weighted undirected cave graph, up to 8 treasure caves, and an air limit, start and end at cave 0 and maximize the number of treasures collected without exceeding the budget.	Hard8	GraphShortest path+2	No attempts yet	5s	128 MB	Judgeable
Magical CraftingGiven binary crafting recipes with diamond costs, decide for each target string of glow stones whether it can be produced from 'A' and find the minimum diamond cost.	Hard8	Dynamic programmingGreedy+2	No attempts yet	5s	128 MB	Judgeable
Epidemic FluFind the set of people infected on day K using repeated multiplication modulo M against the day one infected set.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Caravan RobbersGiven nested-free intervals, place equal-length disjoint subintervals inside them and output the maximum common length as an exact fraction.	Hard8	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
Disjoint Regular ExpressionsGiven two regular expressions, decide whether any non-empty string matches both, and if so print the shortest lexicographically smallest such string.	Hard8	Dynamic programmingBFS+2	No attempts yet	2s	128 MB	Judgeable
Snake CubeGiven a snake cube flattened on a 15x15 grid as 27 labelled cells, fold it back into a 3x3x3 cube and print the lexicographically smallest of all valid layer arrangements.	Hard8	BacktrackingDFS+2	No attempts yet	1s	128 MB	Judgeable
The Great TricksterCount integers from 0 to n whose base-k and base(-k) representations are identical, with n up to 10^15 and k up to 1000.	Hard8	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Kingdom ReunionDecide whether three lists of points form simple polygons and whether the first two are disjoint with union equal to the third.	Hard8	GeometryImplementation+1	No attempts yet	1s	128 MB	Judgeable
Ninja AssignmentChoose a manager and up to budget many ninjas from the manager's subtree, possibly passing through unassigned ninjas, to maximize assigned count times the manager's leadership.	Hard8	TreeDFS+2	No attempts yet	1s	256 MB	Judgeable
KunaiNinjas on a huge grid throw kunai in four directions; kunai vanish when two arrive at the same point at the same instant, so count the squares any surviving kunai passes through.	Hard8	GeometryHash map+2	No attempts yet	3s	256 MB	Judgeable
Finding a PathFind the shortest path on an integer grid where axis-parallel moves can only turn while on a beehive edge, with up to 1000 non-touching rectangular obstacles.	Hard8	GraphShortest path+2	No attempts yet	2s	256 MB	Judgeable
Guess My WordGiven a corpus of words with distinct letters, decide for each corpus whether player A can always win the hangman-like game by secretly switching consistent words.	Hard8	Game theoryBacktracking+2	No attempts yet	2s	256 MB	Judgeable
CommandoPartition soldiers into consecutive blocks, each block's score is a concave quadratic of its sum, and maximize the total score.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	64 MB	Judgeable
PatrolBuild K (1 or 2) unit-length shortcuts in a tree so that the shortest closed walk from village 1 covering every edge exactly as required is minimized.	Hard8	TreeDynamic programming+2	No attempts yet	1s	64 MB	Judgeable
SignalGiven n points with no three collinear and no four concyclic, average over all triples the number of points inside or on the circle through the triple.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Digging for OilPlace three non-overlapping K by K squares on an M by N grid of oil estimates to maximize the total sum covered, with the grid up to 1500 by 1500.	Hard8	Prefix sumDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
ATMGiven a directed graph with cash at each node, find the maximum total cash collectible on a walk from a start node to any restaurant, counting each node once.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Hexagon PerplexagonPlace 7 hexagon pieces in a flower so numbers match on all 12 shared edges, and report the unique valid arrangement.	Hard8	BacktrackingBrute force+2	No attempts yet	2s	128 MB	Judgeable
Have You Driven a Fjord Lately?Choose integer-length bridges across fjords, each spanning one fjord, to maximize road length saved while total bridge length stays within m.	Hard8	GeometryDynamic programming+2	No attempts yet	5s	128 MB	Judgeable
Target PracticeGiven n points in 3D, find the minimum number of straight lines needed to cover all of them.	Hard8	GeometryDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Stake Your ClaimOn an n by n board with 1 to 10 empty squares, find the current player's optimal move and final score difference under optimal play.	Hard8	Game theoryBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Reliable NetsFor each graph, find the minimum cost of a spanning subgraph that stays connected after removing any single edge, or report that none exists.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	128 MB	Judgeable
Square CountCount all axis-aligned squares whose unit tiles lie in the union of rectangular rooms, where adjacent rooms connect through centered doors.	Hard8	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
HexagramCount how many ways, up to rotation and reflection, the 12 given distinct numbers can be placed on the 12 vertices of a hexagram so all 6 lines share one sum.	Hard8	Brute forceBacktracking+2	No attempts yet	5s	128 MB	Judgeable
Billiard TableA billiard ball must bounce off the table cushions exactly N times before reaching a target point; find the minimum travel distance, with corners counting as two bounces.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Teleport Out!Grid maze with exits; each step you either walk to an adjacent open cell or teleport to a uniformly random open cell. Find the minimum expected number of steps to reach an exit.	Hard8	Dynamic programmingBFS+2	No attempts yet	1s	128 MB	Judgeable
WormsGiven string rewriting rules, find the minimum number of days to grow the target worm from one cell, where each day any subset of cells splits.	Hard8	Dynamic programmingIntervals+1	No attempts yet	2s	128 MB	Judgeable
Triangle WarFrom a partially played Triangle War position, decide with perfect play which player ends up owning more of the 9 small triangles.	Hard8	Game theoryBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Paper RouteWith N+1 nodes and exactly N roads, find the cheapest closed walk from node 0 covering all addresses, then add the campus travel cost from wherever you end.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Recovering the Common Ratio of a Geometric SequenceGiven a shuffled, partially deleted integer geometric sequence, find the common ratio with the largest absolute value (positive on ties), or 0 if none exists.	Hard8	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Harmonious MatricesGiven m and n (up to 40), output the lexicographically smallest nonzero matrix of bits where every cell sees an even number of 1s among itself and its orthogonal neighbors.	Hard8	Bit manipulationGreedy+2	No attempts yet	1s	128 MB	Judgeable
New HorizonsGiven a spherical planet, a throne position and height, decide which object tops rise above Yertle's horizon and print their names sorted alphabetically.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
DivorcePick two disjoint subsets of up to 24 houses with equal sums, maximizing that common sum, and report the value of the houses left out.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	30s	128 MB	Judgeable
Stack MachineFor each pair of intersections, find the shortest route whose sequence of board and leave events forms a balanced stack (empty at start and end).	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
PipesGiven a grid of pipe tiles that may be rotated by multiples of 90 degrees, decide whether the tiles can be oriented so that every internal border edge is covered by lines on both sides or neither side.	Hard8	BacktrackingDFS+2	No attempts yet	1s	128 MB	Judgeable
MeltdownA polygon is lowered into a dissolving liquid at speed v while its sides erode at speed c; find when the liquid first reaches a given interior point.	Hard8	GeometryBinary search+1	No attempts yet	1s	128 MB	Judgeable
Stake Coordinate ReconstructionGiven squared side lengths of triangles connecting numbered stakes in counter-clockwise order, reconstruct integer coordinates of every stake, with the first three fixed.	Hard8	GraphGeometry+2	No attempts yet	1s	128 MB	Judgeable
Moveable MazeEach turn lets you rotate one grid square by 90 degrees and then take one step along matching lines, and you must minimize turns from a start cell to a goal cell.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Rotate to RootGiven a binary tree, compute the height of the tree after each node is rotated to the root one at a time.	Hard8	TreeDFS+2	No attempts yet	1s	128 MB	Judgeable
Laurel CreekGiven a grid with stumps and logs, find the minimum number of moves (traverse, pick up, put down a log) to walk from start to end stump.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Rocket StagesChoose a subsequence of stages, in order, with total mass at most 10000 kg and never negative net acceleration, to maximize the final burnout velocity.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	128 MB	Judgeable
Bus Driver SeungjaeGiven a graph with hotels, a start, and a sightseeing spot, find the shortest closed route that picks up and drops off each hotel while keeping half of the drop-offs within the first half of pick-ups.	Hard8	GraphShortest path+2	No attempts yet	3s	128 MB	Judgeable
Fibonacci WordGiven a bit pattern p and an index n up to 100, count the possibly overlapping occurrences of p inside the Fibonacci word F(n), whose length grows exponentially.	Hard8	String matchingDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
InfiltrationIn a tournament digraph, find the smallest set of vertices whose closed out-neighborhoods cover all vertices, and output the lexicographically smallest such set.	Hard8	GraphGreedy+2	No attempts yet	10s	128 MB	Judgeable
KeysGiven keys attached to rings where rings can link, find the minimum key operations, then ring operations, to split keys into two connected piles owned by two people.	Hard8	GraphGreedy+2	No attempts yet	1s	128 MB	Judgeable
Robot VacuumGiven a convex polygon and an interior start point, find the shortest closed route that touches (or bumps into) every edge and returns to the start.	Hard8	GeometryGreedy+2	No attempts yet	5s	128 MB	Judgeable
Safe CompanySimulate a laser bouncing off / and \ mirrors on a huge grid, then decide whether one mirror inserted in a single empty cell can make the beam exit the bottom-right side, counting all such cells.	Hard8	SimulationImplementation+1	No attempts yet	5s	256 MB	Judgeable
Takeover WarsTwo firms alternate merging their own subsidiaries or absorbing a strictly smaller rival one; decide who wins the takeover war with optimal play.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Secret ProjectFor each test case find the shortest (then lexicographically smallest) sequence of add-a and multiply-by-m operations mapping every input in [p,q] into [r,s], or report impossibility.	Hard8	BFSMath+2	No attempts yet	1s	128 MB	Judgeable
Chip DesignPlace the most widgets on an N x N chip so row counts equal column counts and no row or column exceeds A/B of the total parts.	Hard8	Dynamic programmingGreedy+2	No attempts yet	10s	128 MB	Judgeable
Coffee ShopsFor each query radius m, find the grid intersection reached by the most coffee shops within Manhattan distance m, breaking ties by smallest y then smallest x.	Hard8	Prefix sumGeometry+2	No attempts yet	5s	128 MB	Judgeable
Machine WorksBuy and resell at most one machine at a time over D days, each machine usable from its sale day, to maximize final cash.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
Magic SticksSplit a chain of segments into disjoint runs of consecutive segments, close each run into a cyclic polygon, and maximize the total area, where each polygon's best area is the cyclic one.	Hard8	Dynamic programmingGeometry+2	No attempts yet	8s	128 MB	Judgeable
Mining Your Own BusinessFor each connected mine graph, find the minimum number of escape shafts so that after any single junction collapse every survivor reaches a shaft, and count the ways to place that minimum.	Hard8	GraphDFS+2	No attempts yet	5s	128 MB	Judgeable
PyramidsGiven a count of stones, find the smallest set of distinct high or low pyramids (height at least 2) that uses every stone, breaking ties by maximizing sizes lexicographically, or report impossible.	Hard8	Dynamic programmingGreedy+2	No attempts yet	5s	512 MB	Judgeable
GangsRank all lattice paths of E and S steps from (1,1) to the diagonal at (N,N) by a recursive 'OG' order, and output the run at rank M or ERROR.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	128 MB	Judgeable
CarpoolSplit n people into the fewest 5-seat cars, route each car through its passengers' errand stops, and minimize the maximum car travel time.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
MoonshineGiven the upright fill depth of a coaxial body-neck-shoulder can, find the whiskey depth when the can lies on its side.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
MedalsDecide whether some weight vector of the form (1/n^j, 1/n^k, 1/n^l) with total medals n can make Canada's score strictly exceed every other country's.	Hard8	MathGeometry+2	No attempts yet	1s	128 MB	Judgeable
Structural EquivalenceGiven recursive type definitions with aliases and structs, group type names into the smallest set of lines where each line holds names that are structurally equivalent after full unfolding.	Hard8	Union-findGraph+2	No attempts yet	1s	128 MB	Judgeable
Magic BitstringsGiven a prime p, output the lexicographically smallest non-constant magic bitstring of length p-1, where each row of the modular index matrix must equal the string or its complement.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Brownie Points IIGiven points in the plane, Stan picks a vertical line and Ollie a horizontal line through it; find Stan's guaranteed score and the distinct best Ollie scores.	Hard8	SortingPrefix sum+2	No attempts yet	1s	128 MB	Judgeable
Great CircleGiven latitude and longitude of two cities in degrees and minutes, find the most northerly latitude on the great circle arc between them, or print undefined if it is not unique.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
TreequivalenceGiven two textual tree notations, decide whether they describe the same unrooted planar drawing, allowing any root and cyclic order around each vertex.	Hard8	TreeHash map+2	No attempts yet	1s	128 MB	Judgeable
Treasure MapGiven a disk, a boundary start point, and an interior target, find the minimum total length of axis-aligned or 45-degree steps that stay inside the disk.	Hard8	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Advanced Causal Measurements (ACM)Given n observed events and m causes, place the m causes so all events are causally reachable and the earliest cause time is maximized.	Hard8	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
A Brief GerrymanderChoose A avenue boundaries including 1 and 100 to maximize the number of vertical strips that contain at least one marked neighborhood, given fixed street boundaries.	Hard8	Dynamic programmingSorting+1	No attempts yet	1s	128 MB	Judgeable
Intellectual PropertyGiven two code bases as raw strings, find the k longest maximal substrings of the JCN base that also occur in the TDP base, with exact positions and lengths.	Hard8	String matchingSorting+2	No attempts yet	1s	128 MB	Judgeable
Temple of DuneGiven three points that are vertices of some regular polygon, find the minimum possible number of vertices.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
CatenymsFind the lexicographically smallest ordering of dictionary words where each word's last letter equals the next word's first letter, using every word once.	Hard8	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Jogging TrailsFind the shortest closed walk that traverses every undirected weighted edge at least once, where the walk may start at any vertex.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Return of the JediGiven up to 10 non-overlapping circular trees in the plane, find the shortest path length around them from start to goal point, then divide by the speed of 200 miles per hour.	Hard8	GeometryGraph+2	No attempts yet	1s	128 MB	Judgeable
Discrete LogarithmFor each test case with prime P, base B, and target N, find the smallest L with B^L congruent to N mod P, or report no solution.	Hard8	MathNumber theory+2	No attempts yet	1s	128 MB	Judgeable
Snow ClearingFind the minimum time to plow every directed lane of a city's two-way streets and return to the hangar, given faster travel on already-cleared lanes.	Hard8	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Bounding BoxGiven three vertices of a regular n-gon, find the area of the smallest axis-aligned rectangle enclosing the whole polygon.	Hard8	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
SubwayGiven distance, top speed, acceleration limit, and jerk limit, compute the minimum time to move a train between two stops.	Hard8	MathSimulation+1	No attempts yet	1s	128 MB	Judgeable
Hotter ColderAfter each move with a Hotter, Colder, or Same hint, compute the total area where the hidden object can still lie inside a 10 by 10 square.	Hard8	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
Language CardinalityCount the distinct strings a string-rewriting grammar generates from a start string, printing Too many. if the count exceeds 1000.	Hard8	StringBFS+2	No attempts yet	1s	128 MB	Judgeable
Tail PalindromeGiven two lowercase strings a and b, find the shortest string x such that exactly one of ax, bx is a palindrome, and among ties the lexicographically smallest x.	Hard8	StringString matching+2	No attempts yet	1s	128 MB	Judgeable
Maze EscapeFind the shortest fixed sequence of moves that forces escape from every possible free starting cell in an n x n maze, tie-broken lexicographically.	Hard8	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Boastin' Red SocksGiven a target probability p/q, find the red and black sock counts (total at most 50000) whose two-red draw probability equals p/q, minimizing total then reds.	Hard8	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
SpaghettiDecide whether two labeled Fortran IV programs run the same sequence of statements for every input, ignoring unconditional gotos and labels.	Hard8	GraphImplementation+2	No attempts yet	1s	128 MB	Judgeable
Crypt KickerDecrypt each line of a substitution cipher so every word appears in a given dictionary, choosing the lexicographically smallest result, or mask the line if none exists.	Hard8	BacktrackingString+2	No attempts yet	1s	128 MB	Judgeable
Leaps Tall Buildings (in a Single Bound)Given a city skyline of buildings with widths and heights, find the lowest parabolic leap from ground to ground that clears every building, and print its peak altitude rounded to two decimals.	Hard8	GeometryBinary search+2	No attempts yet	1s	128 MB	Judgeable
Ritual CircleFind the smallest circle enclosing all companions with every Orc strictly outside, and report the squared radius as an exact fraction.	Hard8	GeometryBrute force+1	No attempts yet	5s	128 MB	Judgeable
Saruman's Level UpFor each N up to 10^16, count how many integers i in [1, N] have a binary digit sum that is a multiple of 3.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable