Problems

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Total results29,278 problems

Four Substrings
Medium7
String matching, Intervals+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mountain Climbing
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Power Sum
Medium7
Math, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Box Filling
Medium7
Math, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Dial Lock
Medium7
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
New Magic Square
Medium7
Backtracking, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number of Routes Arriving at the Exact Time
Medium7
Matrix, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
New Operator
Medium7
Math, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Binary Search Tree
Medium7
Tree, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Equal-Length Subarray Sum Difference
Medium7
Prefix sum, Sliding window+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Finding Domino Tilings
Medium7
Backtracking, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Square-Free Number
Medium7
Number theory, Binary search+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number of Drawings
Medium7
Geometry, Union-find+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Amusement Park
Medium7
Binary search, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Stair Numbers
Medium7
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Oh Sejun
Medium7
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Median
Medium7
Sliding window, Heap+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rook Attack
Medium7
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Graduation
Medium7
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
DNA Score
Medium7
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Treasure Hunt
Medium7
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Traffic Enforcement
Medium7
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Pastures
Medium7
DFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sequence Restoration
Medium7
Hash map, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Youngsik Function
Medium7
Dynamic programming, Recursion+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
ASCII Art
Medium7
Geometry, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cutting a Square
Medium7
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Drum Message
Medium7
Graph, DFS+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Letters on the Wall
Medium7
Intervals, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Deque Sort
Medium7
Greedy, Binary search+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Lighting Fixture
Medium7
Bit manipulation, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
O Yeongsik's Treasure
Medium7
Recursion, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Line Fighter
Medium7
Binary search, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Once Opened, You Can't Stop
Medium7
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sharp Eyes
Medium7
Binary search, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Counting Single-Letter Triangles
Medium7
Dynamic programming, Matrix+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Wobbling Round Table
Medium7
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Increasing Rectangle Set
Medium7
Dynamic programming, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Music
Medium7
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Top Shelf of the Bookshelf
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Game 2
Medium7
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Permutation
Medium7
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Security Panel
Medium7
Matrix, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bungeoppang Tycoon
Medium7
Brute force, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Dividing Points
Medium7
Geometry, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maximum Sum of a Two-Dimensional Array
Medium7
Brute force, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Trash Cleanup
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Racing Results
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Largest Square Killer
Medium7
String matching, Binary search+2
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Inverse Descent Permutations
Medium7
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Triangles in a Planar Graph
Medium7
Graph, Hash map+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
ASCII Labyrinth
Medium7
BFS, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Period Prediction
Medium7
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Distance in Cone Coordinates
Medium7
Geometry, Math
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bishops
Medium7
Graph, DFS+2
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Internet Installation
Medium7
Binary search, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Multiple-of-Four Prefix Sequence
Medium7
Math, Binary search+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stepping-Stone Race 2
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Constructing a Permutation
Medium7
Combinatorics, Greedy+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
First Sudoku Mistake
Medium7
Backtracking, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Farmland Leveling
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making a Convex Polygon
Medium7
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Pairing
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Finding the K-th Shortest Path
Medium7
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Ballerino
Medium7
Shortest path, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Parcel Delivery
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Removing Stones
Medium7
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Treasure Hunt
Medium7
Tree, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cutting Colored Paper
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tetris Stacking
Medium7
Dynamic programming, Simulation+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Bouncing Bowling Ball
Medium7
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Network Monitoring
Medium7
Graph, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Mold
Medium7
Simulation, Matrix+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Gift Exchange
Medium7
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Seat Swapping
Medium7
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Winning Practice
Medium7
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Skyline
Medium7
Heap, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Expression Representation
Medium7
Dynamic programming, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sitting and Standing
Medium7
Bit manipulation, Math+1
No attempts yet
Time limit
10s
Memory limit
128 MB
Judgeable
Bookcase Construction
Medium7
Dynamic programming, Sorting+1
No attempts yet
Time limit
5s
Memory limit
128 MB
Judgeable
Sum of Numbers 3
Medium7
Sorting, Math+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Ladder Game
Medium7
Dynamic programming, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Increasing Sequence
Medium7
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Number Game
Medium7
Dynamic programming, Game theory+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Wire Connection
Medium7
Geometry, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Two-Dimensional Vectors
Medium7
Geometry, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Overlapping Line Segments
Medium7
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Counting Base Representations
Medium7
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Rainfall
Medium7
Binary search, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Image Energy
Medium7
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Collecting Gems
Medium7
Binary search, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Confining the Black Goat
Medium7
Sorting, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Final Drive Route
Medium7
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Shortest Path on a Triangular Grid
Medium7
Math, Geometry+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Point Selection
Medium7
Sliding window, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Making Balance Weights
Medium7
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Chip Construction
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Building a Tournament
Medium7
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Weakness in an Encryption Algorithm
Medium7
Binary search, Array+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Line Up
Medium7
Topological sort, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Four SubstringsGiven a string and four of its substrings, pick one occurrence of each so that the union of the covered positions has the fewest and the most distinct characters.	Medium7	String matchingIntervals+2	No attempts yet	2s	512 MB	Judgeable
Mountain ClimbingGiven a height grid with move costs that differ by direction, find the highest cell reachable on a round trip from (0,0) within a time limit using shortest-path search.	Medium7	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
Power SumCompute 1^K + 2^K + ... + N^K modulo 1,000,000,007 for N up to 10^9 and K up to 50.	Medium7	MathCombinatorics+1	No attempts yet	2s	128 MB	Judgeable
Box FillingGiven a length x width x height box and limited counts of power-of-two sized cubes, find the minimum number of cubes to fill it exactly, or -1 if impossible.	Medium7	MathBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Dial LockGiven a current dial state and a password of N digits, find the minimum number of operations, each rotating a contiguous block of at most three circular dials by 1 to 3 steps, to reach the password.	Medium7	Dynamic programmingMath+2	No attempts yet	2s	128 MB	Judgeable
New Magic SquareFill a 5x5 grid with numbers 1 to 25 so each row strictly increases, respecting up to one prefilled cell per row, and output the lexicographically smallest valid grid or -1.	Medium7	BacktrackingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Number of Routes Arriving at the Exact TimeCount the number of routes from S to E in a weighted directed graph that take exactly T minutes, modulo 1,000,003.	Medium7	MatrixGraph+2	No attempts yet	2s	128 MB	Judgeable
New OperatorGiven digit-based functions and a custom operator @ built from them, find the minimum number of @ operations starting from X to reach target value G, or report -1.	Medium7	MathDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
Binary Search TreeGiven the insertion order of 0..N-1 values, compute the sum of node heights in the resulting binary search tree efficiently for N up to 250000.	Medium7	TreeDivide and conquer+2	No attempts yet	2s	256 MB	Judgeable
Equal-Length Subarray Sum DifferenceFor every subarray length k, find two non-overlapping equal-length subarrays whose sums differ the least, then report the k (largest on ties) with the smallest such difference.	Medium7	Prefix sumSliding window+2	No attempts yet	5s	128 MB	Judgeable
Finding Domino TilingsCount the ways to tile a fixed 8x7 numeric grid with all 28 distinct dominoes so that each domino's pair matches the covered cell values.	Medium7	BacktrackingBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Square-Free NumberGiven K up to one billion, find the K-th square-free positive integer using number theory and binary search over counting functions.	Medium7	Number theoryBinary search+1	No attempts yet	2s	128 MB	Judgeable
Number of DrawingsGiven T polylines defined by their points, count how many separate connected drawings form when polylines that touch or overlap are merged into one group.	Medium7	GeometryUnion-find+2	No attempts yet	2s	128 MB	Judgeable
Amusement ParkGiven ride durations and a queue of N children, find which numbered ride the last child in line boards, using binary search on time and counting boardings per ride.	Medium7	Binary searchMath+2	No attempts yet	2s	128 MB	Judgeable
Stair NumbersCount N-digit numbers whose adjacent digits differ by exactly 1 and that contain every digit 0-9 at least once, modulo 1,000,000,000.	Medium7	Dynamic programmingBit manipulation+1	No attempts yet	2s	128 MB	Judgeable
Oh SejunConstruct the lexicographically smallest length-N repeating sequence of U/R moves that makes a robot land exactly on a target cell, or report impossibility.	Medium7	GreedyMath+2	No attempts yet	2s	128 MB	Judgeable
MedianGiven N temperature readings, compute the sum of medians of every contiguous window of length K using an efficient order-statistics structure.	Medium7	Sliding windowHeap+2	No attempts yet	1s	128 MB	Judgeable
Rook AttackGiven an R by C board with N unusable squares, find the maximum number of non-attacking rooks that can be placed on the remaining squares.	Medium7	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
GraduationMatch already-taken and newly taken courses to graduation requirements via bipartite matching, minimizing extra courses and finding the lexicographically smallest such set.	Medium7	GraphGreedy+2	No attempts yet	2s	128 MB	Judgeable
DNA ScoreGiven N equal-length DNA strings, design a symmetric, zero-sum score matrix with bounded entries to maximize the average pairwise alignment score.	Medium7	GreedyMath+2	No attempts yet	2s	128 MB	Judgeable
Treasure HuntGiven a grid where the player travels down-right, then up-left, then down-right again, find the maximum treasure collected counting each cell only once per visit.	Medium7	Dynamic programmingMatrix+1	No attempts yet	2s	128 MB	Judgeable
Traffic EnforcementGiven shuffled entry and exit times for N cars, pair them into valid entry-exit matches and find the minimum and maximum total speeding fine over all valid perfect matchings.	Medium7	GraphDynamic programming+2	No attempts yet	2s	128 MB	Judgeable
PasturesGroup adjacent rectangular pastures into connected clusters, find the cluster with the largest bounding-box gap, then pick the smallest pasture whose removal keeps that cluster connected.	Medium7	DFSGraph+2	No attempts yet	2s	128 MB	Judgeable
Sequence RestorationReconstruct any original length-N sequence given all its overlapping length-M contiguous subsequences in arbitrary order.	Medium7	Hash mapGraph+2	No attempts yet	2s	128 MB	Judgeable
Youngsik FunctionCount integers in [A, B] up to 1e9 whose repeated adjacent-digit-difference reduction (the Youngsik function) eventually collapses to the single digit 7.	Medium7	Dynamic programmingRecursion+2	No attempts yet	2s	128 MB	Judgeable
ASCII ArtCompute the exact overlap area of a simple polygon with each unit grid cell using polygon clipping and map the fraction to a character to render ASCII art.	Medium7	GeometrySimulation+1	No attempts yet	2s	128 MB	Judgeable
Cutting a SquareCount how many regions a fixed square is divided into by up to 100 line segments whose endpoints all lie outside the square.	Medium7	GeometryMath+2	No attempts yet	2s	128 MB	Judgeable
Drum MessageGiven K and M, construct a de Bruijn sequence of length K^M on a drum so every length-M string over digits 0..K-1 appears exactly once, or print -1 if impossible.	Medium7	GraphDFS+2	No attempts yet	5s	512 MB	Judgeable
Letters on the WallGiven up to 100 rectangles each filled with one of four parity-based patterns, compute the total number of unit cells that end up marked on the wall.	Medium7	IntervalsMath+2	No attempts yet	2s	128 MB	Judgeable
Deque SortGiven N integers in input order, assign each to a deque (front, back, or new deque) to minimize the number of deques whose concatenation can be sorted nondecreasing.	Medium7	GreedyBinary search+2	No attempts yet	2s	128 MB	Judgeable
Lighting FixtureGiven an N×M grid of colored lamps, find a sequence of row-flip and column-swap button presses that turns the initial grid into a target grid, or report impossibility.	Medium7	Bit manipulationCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
O Yeongsik's TreasureGiven a reachable target Tower of Hanoi arrangement, find the shortest move sequence from the initial all-on-A state and print the disk positions after exactly M moves.	Medium7	RecursionDivide and conquer+2	No attempts yet	1s	128 MB	Judgeable
Line FighterGiven N lines with non-negative slopes and an integer K, find the interval of x where the median of the N line values equals K.	Medium7	Binary searchMath+2	No attempts yet	2s	128 MB	Judgeable
Once Opened, You Can't StopChoose one integer per flavor within its given range so the sum of absolute changes between consecutive picks is minimized, and output the values.	Medium7	Dynamic programmingGreedy+2	No attempts yet	2s	128 MB	Judgeable
Sharp EyesGiven up to 20,000 arithmetic progressions forming a multiset, find the single integer with odd multiplicity using binary search on prefix parity.	Medium7	Binary searchMath+2	No attempts yet	2s	128 MB	Judgeable
Counting Single-Letter TrianglesCount all size-2-or-larger right isosceles and diamond-shaped isosceles triangles made of one repeated letter, in any rotation, inside an N x N grid.	Medium7	Dynamic programmingMatrix+2	No attempts yet	2s	128 MB	Judgeable
Wobbling Round TableGiven circularly arranged table leg lengths, cut some legs so the longest remaining legs strictly enclose the table center, minimizing total length cut.	Medium7	GeometryGreedy+2	No attempts yet	1s	128 MB	Judgeable
Maximum Increasing Rectangle SetGiven N rectangles, find the maximum subset that can be strictly ordered by lower-left to upper-right containment, solvable via DP with a segment tree over compressed coordinates.	Medium7	Dynamic programmingSegment tree+2	No attempts yet	2s	128 MB	Judgeable
MusicInsert non-consecutive rest symbols into three note sequences to equalize their lengths while maximizing a column-matching score, or report impossibility.	Medium7	Dynamic programmingString+1	No attempts yet	2s	128 MB	Judgeable
Top Shelf of the BookshelfPick up to 10 book titles, sorted lexicographically, so that no two neighboring titles share the same letter at any aligned alphabetic position, maximizing total preference score.	Medium7	Dynamic programmingString+2	No attempts yet	2s	128 MB	Judgeable
Number Game 2Given a set of integers and a cap K on how many may be summed, find the first integer that cannot be formed and decide which player loses at that turn.	Medium7	Dynamic programmingMath+2	No attempts yet	2s	128 MB	Judgeable
PermutationGiven a permutation B satisfying B[A[A[i]]] = i, reconstruct a permutation A that produces it, or report that none exists.	Medium7	MathNumber theory+2	No attempts yet	2s	128 MB	Judgeable
Security PanelFind the minimum set of button presses on an R by C panel so a fixed 3x3 toggle pattern turns every button on, breaking ties by a lexicographic rule.	Medium7	MatrixBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Bungeoppang TycoonGiven an MxN grid where pressing a cell flips it and its four neighbors, find the minimum, lexicographically smallest set of presses to make every cell 0.	Medium7	Brute forceBit manipulation+2	No attempts yet	2s	128 MB	Judgeable
Dividing PointsGiven N angular points on a circle, choose the rotation of K equal-angle sectors that minimizes the gap between the most and least populated sectors.	Medium7	GeometrySliding window+2	No attempts yet	2s	128 MB	Judgeable
Maximum Sum of a Two-Dimensional ArrayGiven a 6x6 digit grid, find the maximum total sum achievable by repeatedly adding or subtracting 1 (mod 10) to any row, column, or the two main diagonals.	Medium7	Brute forceMath+2	No attempts yet	2s	128 MB	Judgeable
Trash CleanupGiven a grid with trash cells, find the minimum number of top-left-to-bottom-right monotone paths needed to cover every trash cell.	Medium7	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
Racing ResultsCount how many full car rankings are consistent with given pairwise 'beat' results, essentially counting linear extensions of a partial order mod 1,000,003.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Largest Square KillerGiven an R x C binary grid, find the side length of the largest square submatrix that remains unchanged after a 180 degree rotation.	Medium7	String matchingBinary search+2	No attempts yet	5s	128 MB	Judgeable
Inverse Descent PermutationsCount permutations of size N with a fixed first element F whose inverse permutation has exactly K descents.	Medium7	CombinatoricsDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Triangles in a Planar GraphCount the triangles (3-cycles) in a planar graph with up to 100,000 vertices and 300,000 edges, exploiting the sparse edge bound for efficiency.	Medium7	GraphHash map+2	No attempts yet	2s	128 MB	Judgeable
ASCII LabyrinthGiven a grid of blank, straight, and corner tiles that can be rotated in place, find the shortest path connecting the top-left to the bottom-right corner and count all valid distinct routes.	Medium7	BFSBacktracking+2	No attempts yet	1s	128 MB	Judgeable
String Period PredictionUsing KMP-style prefix functions, find for every prefix the largest period-like split point and sum these values across the whole string.	Medium7	String matchingString+1	No attempts yet	2s	128 MB	Judgeable
Distance in Cone CoordinatesGiven two points on a cone specified by distance from apex and angle, compute the shortest path length that stays on the cone's surface.	Medium7	GeometryMath	No attempts yet	2s	128 MB	Judgeable
BishopsGiven an N by N board with some cells forbidden, find the maximum number of bishops that can be placed so no two attack each other along diagonals.	Medium7	GraphDFS+2	No attempts yet	10s	128 MB	Judgeable
Internet InstallationFind the minimum payment for a path from computer 1 to N when up to K of the priciest cables on that path are installed for free.	Medium7	Binary searchShortest path+2	No attempts yet	2s	128 MB	Judgeable
Multiple-of-Four Prefix SequenceGiven K up to 10^15, find the K-th digit of the infinite string formed by concatenating, for each N, the smallest multiple of 4 that starts with N.	Medium7	MathBinary search+2	No attempts yet	1s	128 MB	Judgeable
Stepping-Stone Race 2Find the minimum total Euclidean jump length from the origin to any stone whose y-coordinate equals a target line, moving only between stones within dx,dy of 2.	Medium7	Shortest pathGraph+2	No attempts yet	2s	128 MB	Judgeable
Constructing a PermutationConstruct the lexicographically smallest and largest permutations of length N whose longest increasing and decreasing subsequences have exact given lengths M and K.	Medium7	CombinatoricsGreedy+2	No attempts yet	2s	128 MB	Judgeable
First Sudoku MistakeGiven 81 sequential Sudoku moves, find the first move after which no digit assignment can complete a valid Sudoku board.	Medium7	BacktrackingSimulation+1	No attempts yet	2s	128 MB	Judgeable
Farmland LevelingGiven N heights forming a 1D terrain, find the minimum number of unit cells to remove so that the number of resulting peaks is at most K.	Medium7	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Making a Convex PolygonGiven a degree-2 graph on N circularly placed points, find the minimum number of points to reposition so the edges form a non-crossing convex polygon, or -1 if impossible.	Medium7	GraphGreedy+1	No attempts yet	2s	128 MB	Judgeable
Number PairingGiven an N x 3 grid, find a perfect domino tiling that maximizes and minimizes the total sum of absolute differences over all pairs.	Medium7	Dynamic programmingGreedy+1	No attempts yet	2s	128 MB	Judgeable
Finding the K-th Shortest PathGiven a directed weighted graph, compute for every city the length of the k-th shortest path from city 1, allowing revisits, or -1 if it does not exist.	Medium7	Shortest pathGraph+1	No attempts yet	2s	256 MB	Judgeable
BallerinoFind the minimum extra cushions needed for a knight-move dancer to reach the goal on a grid with stones, and count how many minimal cushion sets work.	Medium7	Shortest pathBFS+2	No attempts yet	2s	128 MB	Judgeable
Parcel DeliveryGiven each parcel's destination branch along a line, find the minimum cost to deliver all parcels using per-distance trucks and fixed-cost multi-parcel helicopter trips.	Medium7	Dynamic programmingSorting+2	No attempts yet	2s	128 MB	Judgeable
Removing StonesGiven stones on an n by n grid, find the minimum number of row or column sweeps needed to remove every stone, which reduces to minimum vertex cover in a bipartite graph.	Medium7	GraphDFS+2	No attempts yet	2s	128 MB	Judgeable
Treasure HuntGiven a tree of rooms, compute the minimum worst-case number of queries needed to locate a hidden treasure using an optimal centroid-based questioning strategy.	Medium7	TreeDivide and conquer+2	No attempts yet	2s	128 MB	Judgeable
Cutting Colored PaperGiven a simple polygon and a horizontal or vertical cutting line, compute the number of pieces the polygon splits into after the cut.	Medium7	GeometrySorting+2	No attempts yet	2s	128 MB	Judgeable
Tetris StackingGiven a sequence of up to 100 Tetris pieces falling into a width-3 field, choose each piece's rotation and column to minimize the final stack height.	Medium7	Dynamic programmingSimulation+2	No attempts yet	2s	128 MB	Judgeable
Bouncing Bowling BallSimulate a bowling ball bouncing between lane bumpers at a fixed angle and determine, for each distance and angle test case, whether the ball's path comes close enough to touch the pin.	Medium7	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
Network MonitoringGiven several graphs, decide for each whether a vertex cover of size at most 10 exists.	Medium7	GraphBacktracking+1	No attempts yet	1s	128 MB	Judgeable
MoldSimulate mold clusters expanding daily by growth speed (with higher speed winning ties) and find how many days until all mold merges into a single connected cluster.	Medium7	SimulationMatrix+2	No attempts yet	2s	128 MB	Judgeable
Gift ExchangeGiven a functional graph where each of N students names two chosen recipients, select the largest subset of students such that every selected student receives exactly two gifts from other selected students.	Medium7	GraphGreedy+1	No attempts yet	2s	128 MB	Judgeable
Seat SwappingGiven N students each with a team label (K up to 8), find the minimum adjacent swaps to group each team into one contiguous block in some chosen team order.	Medium7	Dynamic programmingBit manipulation+1	No attempts yet	2s	128 MB	Judgeable
Winning PracticeGiven a graph, assign each vertex to one of two groups so that every vertex has an even number of same-group neighbors, and output one valid group.	Medium7	GraphDFS+1	No attempts yet	2s	128 MB	Judgeable
SkylineGiven up to 100,000 rectangular buildings, compute the merged skyline as a sequence of x-coordinate and height key points using a sweep with a heap.	Medium7	HeapSorting+1	No attempts yet	2s	128 MB	Judgeable
Expression RepresentationCompute the minimum number of 1-symbols needed to build an integer n using +, *, ! and parentheses, using DP over factorial and multiplicative decompositions.	Medium7	Dynamic programmingMath+1	No attempts yet	2s	128 MB	Judgeable
Sitting and StandingSimulate a cyclic cellular automaton of standing or sitting students for up to a billion steps efficiently using the XOR-with-neighbor structure.	Medium7	Bit manipulationMath+1	No attempts yet	10s	128 MB	Judgeable
Bookcase ConstructionPartition n books into three non-empty groups to minimize the sum of per-shelf maximum heights times the maximum total thickness of any shelf.	Medium7	Dynamic programmingSorting+1	No attempts yet	5s	128 MB	Judgeable
Sum of Numbers 3Given all pairwise sums of N hidden integers in arbitrary order, reconstruct the lexicographically smallest non-decreasing sequence producing exactly that multiset of sums.	Medium7	SortingMath+2	No attempts yet	2s	128 MB	Judgeable
Ladder GameGiven a ladder diagram, find the minimum cost of removing existing rungs and adding new rungs so a traveler starting at column a ends at column b.	Medium7	Dynamic programmingSimulation+1	No attempts yet	2s	128 MB	Judgeable
Increasing SequenceGiven a digit string up to 80 characters, split it into a strictly increasing sequence of integers (leading zeros allowed) minimizing the last number's value.	Medium7	Dynamic programmingString+1	No attempts yet	2s	128 MB	Judgeable
Number GameGiven a sequence of numbers, determine the winner of a two-player suffix-removal game where each player takes a suffix block ending at the current rightmost element and minimizes their own total sum, for three separate games with n up to 3000.	Medium7	Dynamic programmingGame theory+1	No attempts yet	2s	128 MB	Judgeable
Wire ConnectionDecide whether a subset of given semicircular wires can be joined end to end, with free rotation at joints, to form one closed non-overlapping loop.	Medium7	GeometryDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Two-Dimensional VectorsSelect a subset of up to 30000 planar vectors to maximize the squared length of their sum, requiring an angular sweep or divide-and-conquer geometric technique.	Medium7	GeometryDivide and conquer+1	No attempts yet	2s	128 MB	Judgeable
Overlapping Line SegmentsCount unordered pairs among up to 100,000 line segments that overlap in more than a single point.	Medium7	GeometrySorting+1	No attempts yet	2s	256 MB	Judgeable
Counting Base RepresentationsCount the ways to split a digit string into a base suffix and a sequence of no-leading-zero digit values all less than that base.	Medium7	Dynamic programmingString+1	No attempts yet	2s	128 MB	Judgeable
RainfallGiven partial yearly rainfall records, decide for each query whether a claimed record-rain statement between two years is definitely true, possibly true, or impossible.	Medium7	Binary searchArray+1	No attempts yet	2s	128 MB	Judgeable
Image EnergyAssign each grid cell to black or white to minimize per-cell cost plus adjacency mismatch cost, solvable via min-cut on a grid graph.	Medium7	GraphDynamic programming+1	No attempts yet	2s	128 MB	Judgeable
Collecting GemsGiven N gem values, find a contiguous subarray of length at least M that maximizes floor(1000*sum/length), using binary search on the average.	Medium7	Binary searchPrefix sum+1	No attempts yet	2s	128 MB	Judgeable
Confining the Black GoatGiven N non-overlapping (but nestable) rectangles, find the maximum nesting depth achievable at a point and how many regions attain that depth.	Medium7	SortingGeometry+1	No attempts yet	2s	128 MB	Judgeable
Final Drive RouteGiven a graph where only minimum-fatigue outgoing edges per city are usable, find the S to T route minimizing total fatigue then total length, detecting unreachable or unbounded (negative cycle) cases.	Medium7	GraphShortest path+1	No attempts yet	2s	128 MB	Judgeable
Shortest Path on a Triangular GridGiven two cell indices in a triangular grid of small triangles arranged by rows, compute the minimum number of edge-adjacent moves between them for numbers up to one billion.	Medium7	MathGeometry+1	No attempts yet	2s	128 MB	Judgeable
Point SelectionGiven weighted 2D points, find a placement of a fixed-size axis-aligned rectangle maximizing the difference between the maximum and minimum weights of points it covers.	Medium7	Sliding windowSorting+1	No attempts yet	2s	128 MB	Judgeable
Making Balance WeightsGiven n, construct a permutation of 1..n so that each index i paired with its image sums to a power of two.	Medium7	GreedyMath+1	No attempts yet	2s	256 MB	Judgeable
Chip ConstructionGiven N component priorities and K non-crossing power lines each serving up to two components, find a nesting-valid pairing that maximizes total sum of squares/products.	Medium7	Dynamic programmingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Building a TournamentGiven a sequence of distinct ranks, build a bracket by repeatedly merging adjacent intervals (like matches in a tournament) minimizing the total sum of absolute rank differences over all merges.	Medium7	Dynamic programmingDivide and conquer+1	No attempts yet	2s	128 MB	Judgeable
Weakness in an Encryption AlgorithmGiven a sequence, decide if four indices p<q<r<s exist forming a specific interleaved value pattern, requiring an efficient algorithm beyond brute force for n up to 5000.	Medium7	Binary searchArray+2	No attempts yet	2s	128 MB	Judgeable
Line UpGiven N students and M precedence constraints, compute the minimum and maximum possible position each student can occupy in any valid linear order, or report impossibility if a cycle exists.	Medium7	Topological sortGraph+1	No attempts yet	2s	128 MB	Judgeable