Problems

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Total results29,171 problems

The Running Man
Medium7
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Task Execution
Medium7
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cycle Detection
Medium7
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
QuadTrees
Medium7
Tree, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Value of an Expression
Medium7
BFS, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Road
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Making test data 1
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Making test data 6
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
3D Printer
Medium7
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Unreal Estate
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Uniform Subtrees
Medium7
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
House Construction
Medium7
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Color Palette
Medium7
Trie, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Restore the Expense Indentation
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Multi-Element Binary Search Tree
Medium7
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Grades
Medium7
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Classroom Attention
Medium7
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rally
Medium7
Dynamic programming, Implementation+1
No attempts yet
Time limit
6s
Memory limit
128 MB
Judgeable
The Firearms Market
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Obstacle Course
Medium7
BFS, Geometry+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Disco
Medium7
Intervals, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Vang
Medium7
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Processes
Medium7
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Firewood Pile
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Feather
Medium7
Simulation, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Changing Digits
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cake Cutting
Medium7
Divide and conquer, Recursion+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Swimming Competition
Medium7
Sorting, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cutting a Rectangle
Medium7
Math, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Captain Latvia
Medium7
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Griddy Hobby
Medium7
Simulation, Geometry+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
IOI Photos
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Wiping Words
Medium7
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Points
Medium7
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
ACM-Telecom
Medium7
Trie, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Afshung Pizza Delivery
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Housing Complexes
Medium7
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Illusive Chase
Medium7
Array, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Puzzlestan
Medium7
Union-find, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lazy Math Instructor
Medium7
Hash map, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Convenience Store Part-Timers
Medium7
Greedy, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
An Old Stone Game
Medium7
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Destroying Squares
Medium7
Backtracking, Bit manipulation+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Roads Scholar
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
John's Trip
Medium7
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pipes
Medium7
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
SETI
Medium7
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Minimax Triangulation
Medium7
Dynamic programming, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Irrelevant Elements
Medium7
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Kingdom of Magic
Medium7
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Lattice Animals
Medium7
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
The Game
Medium7
Simulation, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Amusing Numbers
Medium7
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ghost Busters
Medium7
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Team Them Up
Medium7
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Shortest Regular Brackets Sequence
Medium7
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triathlon
Medium7
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Domino Puzzle
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Computer Dialogue
Medium7
Simulation, Hash map+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dictionary
Medium7
Trie, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Gangsters
Medium7
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Buy or Build
Medium7
Minimum spanning tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
UFO Cubes in Roswell
Medium7
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pixel Shuffle
Medium7
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Collecting Bugs
Medium7
Dynamic programming, Probability+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Drawing Windows
Medium7
Geometry, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Jackpot
Medium7
Number theory, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Artinals
Medium7
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Banal Tickets
Medium7
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Longest Common Increasing Subsequence
Medium7
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Invariant Polynomials
Medium7
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Weird Sort
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
The Very Greatest Common Divisor
Medium7
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Collisions
Medium7
Sorting, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dictionary of Obscene Words
Medium7
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hexaroman Numbers
Medium7
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Beam in the Tunnel
Medium7
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Key
Medium7
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Game on Chessboard
Medium7
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Online Shopping
Medium7
Brute force, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rain on Your Parade
Medium7
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Palindromes
Medium7
Simulation, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Knights of the Round Table
Medium7
Geometry, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Escape
Medium7
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pia's Party
Medium7
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quadratic Residue
Medium7
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Regetni
Medium7
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Queen Kingdom
Medium7
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
List Calculator
Medium7
Implementation, Recursion+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bargain or No Bargain
Medium7
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Watching
Medium7
Greedy, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Boy Scout
Medium7
Geometry, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Parity
Medium7
Bit manipulation, Greedy+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Hashing
Medium7
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
The Road to the Classroom
Medium7
Graph, BFS+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Company
Medium7
Graph, Topological sort+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Edit Distance
Medium7
Dynamic programming, String
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Minesweeper
Medium7
Backtracking, Brute force
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ball Painting
Medium7
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fighting for Triangles
Medium7
Game theory, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
The Running ManIn a small grid maze with paths, doors, walls and one entrance, find every single door whose locking alone disconnects the starting path cell from the entrance.	Medium7	GraphBrute force+2	No attempts yet	1s	128 MB	Judgeable
Task ExecutionGiven a DAG of N unit-time tasks, find the minimum completion time with unlimited processors, then the fewest processors that still achieve it.	Medium7	GraphTopological sort+2	No attempts yet	1s	128 MB	Judgeable
Cycle DetectionGiven a graph on at most 20 vertices, for each edge that lies on a cycle, count how many distinct simple cycles contain it.	Medium7	GraphBrute force+2	No attempts yet	1s	128 MB	Judgeable
QuadTreesGiven pre-order strings of two quadtrees for N x N binary images, count the nodes in the quadtree of their pixelwise AND intersection, collapsing uniform quadrants.	Medium7	TreeDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
The Value of an ExpressionGiven a starting value a, use the operation x#y = (digit sum of x)*(max digit of y) + (min digit of y) and find the fewest operations to reach K, or report NEVAR.	Medium7	BFSMath+2	No attempts yet	1s	128 MB	Judgeable
RoadFind the shortest path from A to B along the edges of N axis-aligned rectangles.	Medium7	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
Making test data 1Construct one shortest-path test input that makes Floyd-Warshall exceed 10^6 operations while keeping Dijkstra under it, using as few integers as possible.	Medium7	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Making test data 6Print a fixed directed weighted graph with K triangles and Q queries that makes ModifiedDijkstra exceed a counter limit while OptimizedBellmanFord stays under it.	Medium7	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
3D PrinterCompute the union volume of up to 100 non-overlapping convex polyhedra given by their polygonal faces.	Medium7	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Unreal EstateGiven up to 5000 rectangles with real coordinates, compute the total area their union covers, counting overlaps once, and print it rounded to two decimals.	Medium7	GeometrySorting+2	No attempts yet	10s	128 MB	Judgeable
Uniform SubtreesGiven a parenthesis-encoded tree, list every distinct uniform subtree (same child count at each depth) in lexicographic order.	Medium7	TreeDFS+2	No attempts yet	3s	128 MB	Judgeable
House ConstructionFind the minimum number of days to build L houses given that factories cost Y planks and occupy plot space, produce 10 planks per day, and planks expire nightly.	Medium7	ImplementationSimulation+2	No attempts yet	1s	128 MB	Judgeable
Color PaletteMaintain a set of K-bit colors under insertions and, for each query color, return the stored color with the maximum number of matching bit positions, breaking ties by smallest value.	Medium7	TrieBit manipulation+2	No attempts yet	3s	1024 MB	Judgeable
Restore the Expense IndentationGiven pre-order amounts where each parent equals the sum of its immediate children, recover the lexicographically smallest 0-based indentation depth for every line.	Medium7	Dynamic programmingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Multi-Element Binary Search TreeGiven sorted search probabilities and level-dependent node capacities, find the minimum expected number of comparisons for a multi-element BST.	Medium7	Dynamic programmingTree+1	No attempts yet	1s	1024 MB	Judgeable
GradesInsert Juku into a presentation order to maximize the grades he receives, where grades either reflect project value or reciprocate a prior grade.	Medium7	GreedyPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Classroom AttentionGiven a grid of digits, find the largest possible increase in the sum of each cell's average absolute difference to its orthogonal neighbors after swapping exactly two cells.	Medium7	ImplementationBrute force+1	No attempts yet	1s	1024 MB	Judgeable
RallyChoose a subset of at most 25 stations and fuel amounts to minimize total driving time plus refueling stops.	Medium7	Dynamic programmingImplementation+1	No attempts yet	6s	128 MB	Judgeable
The Firearms MarketFind the largest number of firearms that can be carried from state 1 to state N along a path of total length at most K, where each state on the path caps the carried amount and state 1 and N are uncapped.	Medium7	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
Obstacle CourseFind the minimum number of one-second straight-line moves for a puck starting at rest at the origin, where each flick changes a velocity component by 1 m/s up to 7, avoiding stick obstacles and ending exactly on the target point.	Medium7	BFSGeometry+2	No attempts yet	2s	128 MB	Judgeable
DiscoGiven N disjoint lit intervals on a line of L lamps and M switches that each flip a range, decide if some subset of switches turns every lamp off.	Medium7	IntervalsGreedy+2	No attempts yet	1s	1024 MB	Judgeable
VangOn a polygonal grid yard, a guard moving twice per turn chases a prisoner who can move or wait; report the guard turn when capture happens.	Medium7	BFSGraph+2	No attempts yet	1s	1024 MB	Judgeable
ProcessesGiven N queues of tasks, a limited number K of process splits, and one task completed per process per second, find the minimum time to finish all tasks.	Medium7	Binary searchGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Firewood PileGiven N logs of given lengths, stack them in alternating single-log and crosswise layers, each layer sized by the logs below, to minimize total pile height.	Medium7	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
FeatherA feather drifts across a windy grid where whirlwind directions rotate clockwise each second; determine whether it lands, exits the island, or drifts forever, and report the relevant cell.	Medium7	SimulationGraph+2	No attempts yet	1s	1024 MB	Judgeable
Changing DigitsFind the largest number reachable from N by changing one digit at a time so that each new value's remainder modulo M strictly increases.	Medium7	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Cake CuttingCount the distinct rectangular pieces that can be left after repeatedly halving a cake into two equal halves with equal candle counts.	Medium7	Divide and conquerRecursion+1	No attempts yet	1s	1024 MB	Judgeable
Swimming CompetitionGroup N swimmer times into consecutive sorted blocks of size between A and B, minimizing the largest within-group time difference.	Medium7	SortingDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Cutting a RectangleGiven K rectangles with distinct longer sides, find every possible shorter side of an original rectangle that can be cut into exactly these pieces.	Medium7	MathSorting+1	No attempts yet	1s	1024 MB	Judgeable
Captain LatviaChoose left and right wall points so the triangle through (X,0) covers as many given enemy points as possible; output the maximum count.	Medium7	GeometryGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Griddy HobbyStarting from a boundary point, draw a 45-degree diagonal, then perpendicular segments until the path closes or stalls; count the minimal rectangles carved out.	Medium7	SimulationGeometry+2	No attempts yet	1s	128 MB	Judgeable
IOI PhotosEach order lists photo ranges on named rolls; choose for every roll to print individually, print the whole roll, or buy all rolls, minimizing total cost.	Medium7	Dynamic programmingGreedy+2	No attempts yet	1s	128 MB	Judgeable
Wiping WordsRepeatedly blank out any word whose column has no support in the next line, or that appears in the last line, until no more words can be wiped.	Medium7	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
PointsGiven up to 10000 directional rules between n points, decide whether real coordinates satisfy all of them at once.	Medium7	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
ACM-TelecomGiven a prefix table that assigns costs to 8-digit numbers, find the minimum number of prefix rows preserving every number's charged cost.	Medium7	TrieGreedy	No attempts yet	1s	128 MB	Judgeable
Afshung Pizza DeliveryGiven an ASCII street map with rotating traffic lights at intersections, find the minimum travel time from S to D, or report impossible.	Medium7	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
Housing ComplexesEach plot can be cleared only for one owner, and each owner can be cleared on one plot; maximize the number of h by w complexes built.	Medium7	Binary searchGreedy+2	No attempts yet	1s	128 MB	Judgeable
Illusive ChaseGiven a grid with obstacles and a log of chase trips, each recorded as a range of steps in one direction, count the possible starting cells consistent with the whole sequence.	Medium7	ArrayBrute force+2	No attempts yet	1s	128 MB	Judgeable
PuzzlestanGiven N groups of M lettered items and statements about which items share or do not share an owner, reconstruct the full assignment of items to guests.	Medium7	Union-findBacktracking+2	No attempts yet	1s	128 MB	Judgeable
Lazy Math InstructorDecide whether two arithmetic expressions with left-to-right equal-precedence operators are identical as polynomials over single-letter variables.	Medium7	Hash mapString+2	No attempts yet	1s	128 MB	Judgeable
Convenience Store Part-TimersHire the fewest of N applicants, each working a fixed 8-hour shift starting at a given hour, so every hour of the 24-hour day meets its staffing requirement.	Medium7	GreedyBrute force	No attempts yet	1s	128 MB	Judgeable
An Old Stone GameFor each of up to 10 general trees, compute the minimum number of stones needed so that starting from the bucket you can place a stone on the root by combining stones at fully occupied siblings.	Medium7	TreeGreedy+2	No attempts yet	1s	128 MB	Judgeable
Destroying SquaresGiven an n x n matchstick grid (n <= 5) with some sticks already removed, find the minimum number of additional sticks to remove so that no square remains complete.	Medium7	BacktrackingBit manipulation+2	No attempts yet	5s	128 MB	Judgeable
Roads ScholarGiven a small weighted graph, cities, and signs placed on roads, list every city whose shortest path from the intersection behind the sign starts along that road, printing rounded distances.	Medium7	Shortest pathGraph+2	No attempts yet	1s	128 MB	Judgeable
John's TripFind an Euler circuit in a connected multigraph that uses every street exactly once and is lexicographically smallest by street sequence, starting at the smaller endpoint of the first street.	Medium7	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
PipesGiven a grid of modules with costs on interior walls, find the minimum-cost cycle that visits every module exactly once, starting and ending at the service module.	Medium7	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
SETIRecover the coefficients a_0..a_{n-1} of a polynomial over a prime field from its values at k = 1..n.	Medium7	MathNumber theory+1	No attempts yet	1s	128 MB	Judgeable
Minimax TriangulationFind the triangulation of a simple polygon minimizing the largest triangle's area, and report that area.	Medium7	Dynamic programmingGeometry+1	No attempts yet	1s	128 MB	Judgeable
Irrelevant ElementsRepeatedly replace an array with adjacent sums until one value remains mod m; find which original positions never affect that value.	Medium7	MathNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Kingdom of MagicOn a graph of up to 100 cities, two people who must always sit on adjacent distinct vertices move to a target adjacent pair, minimizing total single or paired moves.	Medium7	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
Lattice AnimalsCount free n-polyominoes (up to rotation and reflection) that fit inside a w by h rectangle, with n up to 10.	Medium7	BacktrackingBrute force+2	No attempts yet	2s	128 MB	Judgeable
The GameGiven N and a count M of 'I don't know' answers, find all pairs the master could have chosen in the sum-product guessing game.	Medium7	SimulationMath+2	No attempts yet	1s	128 MB	Judgeable
Amusing NumbersGiven K and M, find the smallest N such that K sits at lexicographic position M among the numbers 1 to N.	Medium7	MathBinary search+2	No attempts yet	1s	128 MB	Judgeable
Ghost BustersA ray from the origin inside the octant X,Y,Z >= 0 must be aimed to graze (touch) as many spheres as possible; report the maximum count.	Medium7	GeometryMath+2	No attempts yet	1s	128 MB	Judgeable
Team Them UpSplit N people into two teams where teammates must mutually know each other, minimizing the size difference, and report the two team sizes.	Medium7	GraphDFS+2	No attempts yet	1s	128 MB	Judgeable
Shortest Regular Brackets SequenceGiven a string of brackets, find the length of the shortest regular bracket sequence that contains it as a subsequence.	Medium7	Dynamic programmingIntervals+2	No attempts yet	1s	128 MB	Judgeable
TriathlonFor each contestant, decide whether positive stage lengths exist that make their total time uniquely smallest.	Medium7	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Domino PuzzleAdd dominoes of minimum total pip-sum so that all pieces form one row with matching ends, an Eulerian path completion on values 1 to 6.	Medium7	GraphShortest path+2	No attempts yet	1s	128 MB	Judgeable
Computer DialogueGiven file names split into name and extension parts, simulate the alternating 'I don't know' messages between two clients and list files still possible after M messages.	Medium7	SimulationHash map+2	No attempts yet	1s	128 MB	Judgeable
DictionaryGiven a list of words, insert leading spaces so the list satisfies a recursive definition: every maximal run of words sharing a first letter must, after removing the first word and that letter, again be a dictionary.	Medium7	TrieRecursion+2	No attempts yet	1s	128 MB	Judgeable
GangstersChoose a door state over time that changes by at most 1 per unit, starting at 0, to maximize the prosperity of gangsters whose stoutness matches the state at their arrival time.	Medium7	Dynamic programmingSorting+1	No attempts yet	1s	128 MB	Judgeable
Buy or BuildPick a subset of up to 8 subnetworks to buy and build edges so all n cities connect, minimizing total cost.	Medium7	Minimum spanning treeGraph+2	No attempts yet	1s	128 MB	Judgeable
UFO Cubes in RoswellGiven a cube with mirrors at integer points, trace every downward light ray and report how many exit each face and how many deflections they took.	Medium7	SimulationImplementation+2	No attempts yet	2s	1024 MB	Judgeable
Pixel ShuffleGiven a permutation of an n by n pixel grid built from at most 32 named transformations, find the smallest positive power that returns the image to its original state.	Medium7	MathImplementation+2	No attempts yet	2s	1024 MB	Judgeable
Collecting BugsFind the expected number of days until a stream of random (category, subsystem) pairs has covered all n categories and all s subsystems.	Medium7	Dynamic programmingProbability+2	No attempts yet	2s	64 MB	Judgeable
Drawing WindowsGiven the boundary of a hole-free rectilinear polygon, compute the minimum number of non-overlapping axis-aligned rectangles that exactly partition it.	Medium7	GeometryDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
JackpotCount integers in [-k, k] divisible by at least one of n values, find the limiting fraction, and print it reduced.	Medium7	Number theoryCombinatorics+1	No attempts yet	2s	64 MB	Judgeable
ArtinalsInterpret a small language over hereditarily finite sets, evaluating assignments, expressions and relations, and print reduced canonical set representations.	Medium7	StringImplementation+2	No attempts yet	1s	512 MB	Judgeable
Banal TicketsGiven a length-2N ticket pattern with unreadable digits, count how many fillings make the first half product equal the second half product, and how many do not.	Medium7	CombinatoricsDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Longest Common Increasing SubsequenceGiven two integer sequences, find the length of the longest common increasing subsequence of both.	Medium7	Dynamic programmingArray+2	No attempts yet	1s	256 MB	Judgeable
Invariant PolynomialsCount the dimension of the space of real polynomials in x, y of degree at most d that are invariant under rotation by 2π/n.	Medium7	MathCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Weird SortReorder N integers so no element equals the previous element plus one, outputting the lexicographically smallest valid ordering or No solution.	Medium7	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
The Very Greatest Common DivisorEach input value is the determinant of a tridiagonal n by n matrix with 1 on the diagonal, 1 above, -1 below; find the gcd of two such determinants.	Medium7	Number theoryMath+2	No attempts yet	2s	128 MB	Judgeable
CollisionsIdentical balls on a line move at constant velocities and swap velocities on elastic collision; count total collisions, or report infinity if unbounded.	Medium7	SortingMath+2	No attempts yet	1s	128 MB	Judgeable
Dictionary of Obscene WordsGiven dictionary words and a text, find the length of the shortest prefix of the text containing some word as a subsequence.	Medium7	Dynamic programmingString+1	No attempts yet	1s	128 MB	Judgeable
Hexaroman NumbersParse and output hexadecimal Roman numerals, choosing the shorter of additive or subtractive notation per digit, then evaluate +, -, and * expressions.	Medium7	StringImplementation+2	No attempts yet	1s	128 MB	Judgeable
Beam in the TunnelGiven floor vertices of a unit-height tunnel, find the minimum number of translators so a straight beam segment between consecutive translators stays strictly inside.	Medium7	GeometryGreedy+2	No attempts yet	1s	128 MB	Judgeable
KeyFind every odd K in [A, B] such that (K-1)! is not a multiple of K^2, where B - A is at most 100 but B can be 10^18.	Medium7	Number theoryMath+2	No attempts yet	1s	128 MB	Judgeable
Game on ChessboardGiven K (p,q)-leapers on an M x N board, decide which player wins the disjunctive sum of impartial games.	Medium7	Game theoryMath	No attempts yet	1s	128 MB	Judgeable
Online ShoppingReorder rows and columns of a matrix so the resulting row-by-row string of prices is lexicographically smallest.	Medium7	Brute forceSorting+2	No attempts yet	1s	128 MB	Judgeable
Rain on Your ParadeGiven guest positions and speeds, umbrella positions, and time t, find the maximum number of guests that can each be matched to a reachable umbrella.	Medium7	GraphBFS+2	No attempts yet	1s	128 MB	Judgeable
PalindromesFor each number in a small interval written in base b, apply reverse-and-add up to l times and count how many do not reach a palindrome.	Medium7	SimulationMath+2	No attempts yet	1s	128 MB	Judgeable
Knights of the Round TableGiven chairs at rational angles on a circle of radius n, find the maximum straight-line distance between any two chairs, rounded to two decimals.	Medium7	GeometryTwo pointers+2	No attempts yet	2s	128 MB	Judgeable
EscapeFind the earliest time in the window [t, t+d) that James can reach the pickup cell, moving one cell per second with no U-turns and no waiting.	Medium7	BFSGraph+2	No attempts yet	2s	128 MB	Judgeable
Pia's PartyPlace four of c given points on a circle of diameter d to maximize the area of the quadrilateral they form.	Medium7	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
Quadratic ResidueFor each test case, compute the Legendre symbol (a/p) for an odd prime p and integer a, using quadratic reciprocity.	Medium7	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
RegetniCount triples of given integer points whose triangle area is an integer, including collinear triples with area 0.	Medium7	MathCombinatorics+2	No attempts yet	1s	128 MB	Judgeable
Queen KingdomOn an n by n board with pillars blocking queens' attacks, find the maximum number of non-attacking queens and the number of placements attaining it.	Medium7	BacktrackingBrute force+2	No attempts yet	2s	128 MB	Judgeable
List CalculatorImplement an interpreter for a small list language with slicing, unary and binary elementwise operators, concatenation, and single-character variable assignment.	Medium7	ImplementationRecursion+2	No attempts yet	1s	128 MB	Judgeable
Bargain or No BargainGiven prize values and a budget M, decide whether optimal play maximizing expected log utility yields expected prize money above M.	Medium7	Dynamic programmingProbability+2	No attempts yet	1s	128 MB	Judgeable
WatchingChoose the smallest w so that P intervals of length w and Q intervals of length 2w together cover all given event sections.	Medium7	GreedyBinary search+2	No attempts yet	1s	128 MB	Judgeable
Boy ScoutGiven N points in general position, find the longest closed route that always turns strictly left at every step, counting distinct points visited.	Medium7	GeometryDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
ParityGiven n binary strings and target bits, find the smallest column subset of size at most k whose XOR over each string matches its bit.	Medium7	Bit manipulationGreedy+2	No attempts yet	10s	512 MB	Judgeable
HashingCount how many of n+1 values of a linear hash modulo m land in an interval [c, d].	Medium7	MathNumber theory+1	No attempts yet	2s	128 MB	Judgeable
The Road to the ClassroomDecide whether K routes from intersection 1 to intersection 2 exist that are internally vertex-disjoint and edge-disjoint on an undirected graph.	Medium7	GraphBFS+2	No attempts yet	3s	128 MB	Judgeable
CompanyKeep the fewest boss relations from a DAG so that reachability between all pairs of employees is unchanged, and output them sorted.	Medium7	GraphTopological sort+1	No attempts yet	1s	128 MB	Judgeable
Edit DistanceGiven strings A and B up to length 17000, find the minimum number of insert, delete, and substitute operations to turn A into B.	Medium7	Dynamic programmingString	No attempts yet	8s	128 MB	Judgeable
MinesweeperGiven a partially revealed Minesweeper grid, mark each unrevealed cell as definitely a mine, definitely safe, or undetermined across all consistent arrangements.	Medium7	BacktrackingBrute force	No attempts yet	1s	128 MB	Judgeable
Ball PaintingCount paint orders on a 2 by N grid where each new ball must touch an already painted ball, modulo 1e9+7.	Medium7	Dynamic programmingCombinatorics	No attempts yet	2s	512 MB	Judgeable
Fighting for TrianglesOn a triangular board with some edges already drawn, two players alternate adding edges, claiming a unit triangle when their edge completes it. Decide the winner with optimal play.	Medium7	Game theoryGraph+2	No attempts yet	2s	512 MB	Judgeable