Problems

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Total results29,085 problems

Butterfly
Medium7
Intervals, Dynamic programming+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Full Text Search
Medium7
String, Graph+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Mysterious Maze
Medium7
BFS, Simulation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Dungeon Quest II
Medium7
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Road Construction
Medium7
Graph, Shortest path+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Operator
Medium7
Simulation, Binary search+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Merry Christmas
Medium7
Shortest path, Dynamic programming+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Futon
Medium7
Graph, Brute force+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Crystal Jails
Medium7
Backtracking, Recursion
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Cave Explorer
Medium7
Geometry, Binary search+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Entangled Tree
Medium7
Tree, DFS+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Sort the Panels
Medium7
Math, Combinatorics
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Alice in Foxland
Medium7
Dynamic programming, String+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Robots' Crash
Medium7
Geometry, Simulation+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Linear Ether Geometry
Medium7
Greedy, Backtracking+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Ruins
Medium7
Math, Number theory+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
The divisor conquers
Medium7
Backtracking, Greedy+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Trees and Primes
Medium7
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Castle
Medium7
String, Trie
No attempts yet
Time limit
0.5s
Memory limit
256 MB
Judgeable
Reading Digits
Medium7
String, Implementation+1
No attempts yet
Time limit
0.1s
Memory limit
256 MB
Judgeable
Pub crawl
Medium7
Geometry, Sorting+1
No attempts yet
Time limit
0.3s
Memory limit
256 MB
Judgeable
Sum of Cubes
Medium7
Dynamic programming, Brute force+2
No attempts yet
Time limit
0.5s
Memory limit
256 MB
Judgeable
Dating On-Line
Medium7
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hotel Rewards
Medium7
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Just in Time
Medium7
Probability, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Permutation Descent Counts
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tight-Fit Sudoku
Medium7
Backtracking, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Average
Medium7
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Aerial Archeology
Medium7
Geometry, Brute force+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cable Connection
Medium7
Geometry, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree Stands
Medium7
Tree, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Orchard Division
Medium7
Geometry, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Suffix Array 3
Medium7
Array, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Free Weights
Medium7
Array, Two pointers+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Iron and Coal
Medium7
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kiwi Trees
Medium7
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Quality Expressions
Medium7
Dynamic programming, Tree+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Convex Contour
Medium7
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jazz Journey
Medium7
Graph, Greedy+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Bribing Eve
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dinner Bet
Medium7
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Performance Review
Medium7
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cairo Corridor
Medium7
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pascal's Hyper-Pyramids
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The White Rabbit's Pocket Watch
Medium7
Graph, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tiling a 3 by N Wall
Medium7
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Maximum Islands
Medium7
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Expect to Wait
Medium7
Prefix sum, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Foreign Postcards
Medium7
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Increasing Subsequence 4
Medium7
Dynamic programming, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Restoring the longest increasing subsequence
Medium7
Dynamic programming, Binary search+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Cars on Ice
Medium7
Topological sort, Graph+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Combining Riceballs
Medium7
Dynamic programming, Intervals+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Circle of Life
Medium7
Bit manipulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Through a Maze Darkly
Medium7
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Biathlon
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cheap Traveling
Medium7
Shortest path, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Blockade Duty Schedule
Medium7
Intervals, Binary search+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Swarm
Medium7
Geometry, Shortest path+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Probability
Medium7
Dynamic programming, Probability+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Pyramid
Medium7
Dynamic programming, Array+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
The Hottest Piece of Cheese
Medium7
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Parquet
Medium7
Math, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Apple
Medium7
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Coin-collecting robot vacuum
Medium7
Graph, Greedy+1
No attempts yet
Time limit
4s
Memory limit
128 MB
Judgeable
Stamping Twice
Medium7
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Archimedes' circles
Medium7
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Formula
Medium7
Graph, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polygon and Lines
Medium7
Geometry, Binary search
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Sorting with allowed swaps
Medium7
Graph, DFS+2
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Equal Digit Products
Medium7
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bananas
Medium7
Geometry, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Zones
Medium7
Implementation, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Segments
Medium7
Geometry, Probability+1
No attempts yet
Time limit
0.5s
Memory limit
256 MB
Judgeable
Two Balls
Medium7
Probability, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stickers
Medium7
String, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
256 MB
Judgeable
Happy sequence
Medium7
Array, Hash map+1
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Majstor
Medium7
Greedy, Sorting+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Safe road system
Medium7
Graph, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Adjacent Product Game
Medium7
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Riva
Medium7
Geometry, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Chemistry
Medium7
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Cake delivery
Medium7
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Team Building
Medium7
Sorting, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lasers and Mirrors
Medium7
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree and Primes
Medium7
Tree, DFS+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Arranging Heaps
Medium7
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Christmas Eve
Medium7
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
MicroRNA Ranking
Medium7
Graph, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Explosion at Cafebazaar
Medium7
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Linear Galaxy
Medium7
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Blocks&Balls
Medium7
Binary search, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sunday Coding
Medium7
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Smallest Square 1
Medium7
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Smallest Square 2
Medium7
Binary search, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Task Processing
Medium7
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Proving Propositions
Medium7
Graph, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Proficiency
Medium7
Probability, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cutting Trees
Medium7
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Wolves
Medium7
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
ButterflyChoose non-overlapping dates; each person pays only if all their dates are kept, so maximize total satisfaction.	Medium7	IntervalsDynamic programming+2	No attempts yet	8s	512 MB	Judgeable
Full Text SearchFor each query, find the shortest letter string whose set of length-1 and length-2 substrings contains the query's set but which does not contain the query itself.	Medium7	StringGraph+2	No attempts yet	8s	512 MB	Judgeable
Mysterious MazeA robot in a grid moves forward or turns according to a fixed sequence of turns; decide whether it can reach the exit once the turns run out.	Medium7	BFSSimulation+2	No attempts yet	8s	512 MB	Judgeable
Dungeon Quest IIGiven a fixed walking route through a grid of traps and up to 12 one-use potions, decide whether the agent can survive to the end.	Medium7	Dynamic programmingBit manipulation+1	No attempts yet	8s	512 MB	Judgeable
Road ConstructionGiven a weighted bidirectional graph, find the minimum total building cost of a spanning subgraph that keeps every pairwise connection and preserves the shortest distance from the capital to every city.	Medium7	GraphShortest path+2	No attempts yet	8s	512 MB	Judgeable
OperatorSimulate callers who retry after hanging up, and find the fewest operators so all calls finish within time T.	Medium7	SimulationBinary search+2	No attempts yet	8s	512 MB	Judgeable
Merry ChristmasGiven a town road network and timed delivery requests, find the minimum number of Santas so every present arrives exactly at its scheduled time.	Medium7	Shortest pathDynamic programming+1	No attempts yet	8s	512 MB	Judgeable
FutonEach domino-like futon must choose one of its two cells as a head; decide whether all head choices can avoid side-adjacent foot-to-head conflicts.	Medium7	GraphBrute force+2	No attempts yet	8s	512 MB	Judgeable
Crystal JailsGiven up to 27 small polycube blocks that may be rotated but not reflected, decide whether they tile a W x D x H box exactly.	Medium7	BacktrackingRecursion	No attempts yet	8s	512 MB	Judgeable
Cave ExplorerCut a simple polygon with a line of given direction, keep the largest piece, and minimize that area over all line positions.	Medium7	GeometryBinary search+1	No attempts yet	8s	512 MB	Judgeable
Entangled TreeGiven a forest of split nodes, order the leaf labels so each split node's leaves are consecutive, choosing the lexicographically smallest sequence, then answer position queries.	Medium7	TreeDFS+2	No attempts yet	8s	512 MB	Judgeable
Sort the PanelsGiven two black/white panel arrangements, find the minimum movement cost to sort one into the other, where each swap of two panels costs 3 plus the distance moved.	Medium7	MathCombinatorics	No attempts yet	8s	512 MB	Judgeable
Alice in FoxlandGiven two strings X and Y, find the longest common subsequence of X and Y that contains a required substring C as a contiguous block, or report impossible; among ties pick the lexicographically smallest.	Medium7	Dynamic programmingString+2	No attempts yet	8s	512 MB	Judgeable
Robots' CrashGiven moving robots with two possible opposite velocities, find the earliest time any two centers come within distance 2r, or report SAFE.	Medium7	GeometrySimulation+1	No attempts yet	8s	512 MB	Judgeable
Linear Ether GeometryConnect N libraries on a hallway to the internet using M cables and hubs, minimizing hubs first then total cable slack.	Medium7	GreedyBacktracking+1	No attempts yet	8s	512 MB	Judgeable
RuinsFor each pair a, b up to 10000, choose factorizations a=a1a2 and b=b1b2 to order four numbers so the sum of squared consecutive gaps is minimal.	Medium7	MathNumber theory+2	No attempts yet	8s	512 MB	Judgeable
The divisor conquersPlace the N cards one at a time so each new card divides the sum of the cards already down, and print the lexicographically smallest winning order or No.	Medium7	BacktrackingGreedy+2	No attempts yet	8s	512 MB	Judgeable
Trees and PrimesGiven a tree on N vertices, find the probability that a uniformly random pair of distinct vertices has a prime distance.	Medium7	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
CastleMaintain a growing string under appends, insertions of the whole current string into a set, and queries counting how many stored strings are suffixes of the current string.	Medium7	StringTrie	No attempts yet	0.5s	256 MB	Judgeable
Reading DigitsDecode the given run-length-encoded string k times, then report the digit at index pos of the original string s.	Medium7	StringImplementation+1	No attempts yet	0.1s	256 MB	Judgeable
Pub crawlFind the longest route through n points where every turn is a left turn, using the given tie-breaking rule.	Medium7	GeometrySorting+1	No attempts yet	0.3s	256 MB	Judgeable
Sum of CubesWrite N as a sum of as few positive cubes as possible, and among the shortest sums output the one that is lexicographically largest.	Medium7	Dynamic programmingBrute force+2	No attempts yet	0.5s	256 MB	Judgeable
Dating On-LineReorder N scores around a regular N-gon to maximize the polygon's area.	Medium7	SortingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Hotel RewardsGiven nightly hotel prices and a K-points-per-free-night reward rule, find the minimum total cost of the whole trip.	Medium7	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Just in TimeGiven N rooms where each room has one random outgoing tunnel, choose T in [2, N] maximizing the chance a walker starting in room 1 is not back in room 1 at time T.	Medium7	ProbabilityMath+2	No attempts yet	2s	512 MB	Judgeable
Permutation Descent CountsCount permutations of order N with exactly v descents, modulo 1001113, for up to 1000 queries with N at most 100.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Tight-Fit SudokuFill a 6 by 6 grid with digits 1 to 9 so no digit repeats in a row, column, or 3 by 2 box, including split squares holding two digits.	Medium7	BacktrackingImplementation+1	No attempts yet	2s	512 MB	Judgeable
AverageCount, over all N-tuples of integer marks from 0 to fullmarks, the total number of teachers whose mark equals the tuple's mean, modulo 1000000007.	Medium7	CombinatoricsDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Aerial ArcheologyGiven several simple polygons that may overlap, find the maximum number of polygons whose interiors a single straight line can pass through.	Medium7	GeometryBrute force+1	No attempts yet	5s	512 MB	Judgeable
Cable ConnectionPlace a segment from (X,0) to (0,Y) so every point (b,a) satisfies b/X + a/Y <= 1, minimizing sqrt(X^2+Y^2).	Medium7	GeometryGreedy+1	No attempts yet	2s	512 MB	Judgeable
Tree StandsCount the K-vertex subsets of a tree in which every chosen vertex is adjacent to at least one other chosen vertex, modulo 1000000007.	Medium7	TreeDynamic programming+1	No attempts yet	5s	512 MB	Judgeable
Orchard DivisionFind the smallest axis-aligned rectangle anchored at one orchard corner that contains exactly half of N given tree coordinates.	Medium7	GeometryPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Suffix Array 3Given a permutation built by moving and reversing intervals, count the strings whose suffix array equals it, modulo 1e9+7.	Medium7	ArrayCombinatorics+2	No attempts yet	5s	512 MB	Judgeable
Free WeightsTwo rows of dumbbells, each mass appearing twice, must be paired up; minimize the heaviest dumbbell that must be lifted.	Medium7	ArrayTwo pointers+2	No attempts yet	4s	512 MB	Judgeable
Iron and CoalGiven a directed graph with iron and coal cells, find the fewest settlers needed to claim at least one iron cell and one coal cell from cell 1.	Medium7	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
Kiwi TreesGiven a simple polygon whose edge lengths and angles are bounded, decide whether two radius-4 disks can be placed inside it without touching each other.	Medium7	GeometryBinary search+1	No attempts yet	2s	512 MB	Judgeable
Quality ExpressionsGiven a bracket expression with ? placeholders and per-arity limits, choose values so the expression is valid and its value is as large as possible.	Medium7	Dynamic programmingTree+1	No attempts yet	1s	64 MB	Judgeable
Convex ContourGiven a row of squares, inscribed circles, and equilateral triangles in a unit grid, compute the length of the convex hull boundary of their union.	Medium7	GeometryMath+2	No attempts yet	1s	512 MB	Judgeable
Jazz JourneyGiven a fixed closed tour and ticket prices for one-way and round-trip fares, find the minimum cost to cover every leg of the tour.	Medium7	GraphGreedy+1	No attempts yet	5s	512 MB	Judgeable
Bribing EveGiven each phone's two integer scores, find the best and worst rank the first phone can get while an adversary picks nonnegative weights and orders ties.	Medium7	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Dinner BetGiven N balls, D drawn per round, and two size-C cards, find the expected number of rounds until one player completes their card.	Medium7	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Performance ReviewFor each employee, sum t_j over all descendants j whose rank r_j is lower than the employee's rank.	Medium7	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Cairo CorridorEach tile is split into two pentagon halves; find the connected clear region touching all four borders and decide whether it is minimal.	Medium7	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Pascal's Hyper-PyramidsCompute the distinct multinomial coefficients on the base layer of a D-dimensional Pascal hyper-pyramid of height H, printed in ascending order.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
The White Rabbit's Pocket WatchGiven walks whose total length is known only modulo 13, recover each edge's true weight in 1..12 and find the shortest path from A to R.	Medium7	GraphNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Tiling a 3 by N WallCount the tilings of a 3 by N wall with dominoes, modulo 1e9+7, where N can be as large as 10^18.	Medium7	Dynamic programmingMatrix+1	No attempts yet	2s	512 MB	Judgeable
Maximum IslandsGiven an n by m grid of land, water, and cloud cells where clouds may be either, maximize the number of 4-connected land components.	Medium7	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Expect to WaitGiven a time-ordered schedule of unicycle drops and grouped requests, compute the total wait time of all requesters for each of several starting unicycle counts, or report infinity if anyone is left waiting.	Medium7	Prefix sumBinary search+2	No attempts yet	2s	512 MB	Judgeable
Foreign PostcardsPlace postcards in random batches, flipping a batch when its top card is upside down, and compute the expected number left picture down.	Medium7	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Longest Increasing Subsequence 4Find a longest strictly increasing subsequence of A, and among all of maximum length output the lexicographically smallest one along with its length.	Medium7	Dynamic programmingBinary search+2	No attempts yet	1s	256 MB	Judgeable
Restoring the longest increasing subsequenceFind the length of the longest strictly increasing subsequence of A and print the lexicographically smallest subsequence achieving that length.	Medium7	Dynamic programmingBinary search+2	No attempts yet	3s	512 MB	Judgeable
Cars on IceCars point in fixed directions and slide out along that direction; find the lexicographically smallest order that pushes every car out without collisions.	Medium7	Topological sortGraph+1	No attempts yet	5s	512 MB	Judgeable
Combining RiceballsGiven a row of riceballs, merge equal adjacent pairs or equal pairs with one ball between them, and find the largest size reachable.	Medium7	Dynamic programmingIntervals+2	No attempts yet	2s	512 MB	Judgeable
Circle of LifeA circular binary strip updates so each cell is alive next generation only if exactly one neighbor is alive; find the state after T generations, with T up to 10^15.	Medium7	Bit manipulationMath+2	No attempts yet	2s	512 MB	Judgeable
Through a Maze DarklyA planar maze lists each room's neighbors in clockwise order; for each starting room, find the longest wall-following (right-hand rule) closed walk before returning to the start.	Medium7	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
BiathlonGiven each competitor's two speeds, find all indexes that can win for some choice of the two track distances.	Medium7	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Cheap TravelingFind a route from village 1 to N whose total fare is at most S and whose total travel time is smallest; rides and villages may repeat.	Medium7	Shortest pathGraph+2	No attempts yet	2s	512 MB	Judgeable
Blockade Duty ScheduleFind the largest M such that a daily duty schedule exists where at least M students are on duty at every moment, respecting each student's free periods and daily minute limit.	Medium7	IntervalsBinary search+1	No attempts yet	1s	512 MB	Judgeable
SwarmGiven a set of allowed compass directions, place all bees on one integer point minimizing the total number of moves.	Medium7	GeometryShortest path+2	No attempts yet	10s	512 MB	Judgeable
ProbabilityGiven probabilities of letters A to D, find the probability that an optimally played game fills a row of n cells in alphabetical order.	Medium7	Dynamic programmingProbability+2	No attempts yet	1.5s	512 MB	Judgeable
PyramidBuild an n-row triangular pyramid from a linear recurrence, then answer queries for the maximum value inside a downward triangular sub-pyramid.	Medium7	Dynamic programmingArray+1	No attempts yet	4s	512 MB	Judgeable
The Hottest Piece of CheeseGiven two families of non-crossing cuts across a rectangle and points inside it, find the piece containing the most peppers.	Medium7	GeometrySorting+1	No attempts yet	1s	512 MB	Judgeable
ParquetA brick-like tiling of the plane shifts by half a tile on every other row; count the tiles touching the border of an axis-aligned rectangle.	Medium7	MathImplementation+2	No attempts yet	1s	128 MB	Judgeable
AppleSimulate gravity, rotations, and waiting on a board with one apple, then print the final board state.	Medium7	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Coin-collecting robot vacuumA vacuum walks 4N steps on an (N+1)x(N+1) grid of coins, must collect all four corners, and return to start; maximize coins.	Medium7	GraphGreedy+1	No attempts yet	4s	128 MB	Judgeable
Stamping TwiceGiven a convex polygon and its translation by a vector, find the total perimeter of the union of the two copies.	Medium7	GeometryImplementation	No attempts yet	1s	128 MB	Judgeable
Archimedes' circlesGiven N black and M white points, find the maximum number of white points lying inside a circle through some three black points.	Medium7	GeometryBrute force+2	No attempts yet	1s	128 MB	Judgeable
FormulaFind the maximum number of edges in a closed trail that uses every important edge at least once, or report that none exists.	Medium7	GraphBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Polygon and LinesFor each line crossing a convex polygon, find the closest polygon vertex to the line and print the distance.	Medium7	GeometryBinary search	No attempts yet	0.5s	128 MB	Judgeable
Sorting with allowed swapsGiven a permutation and allowed swaps, decide if the given pairs can sort it and output the swaps produced by the described leaf-removal rule on the spanning forest.	Medium7	GraphDFS+2	No attempts yet	0.5s	128 MB	Judgeable
Equal Digit ProductsCount N-digit numbers whose digits in odd positions have the same product as the digits in even positions.	Medium7	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
BananasPlace a spiral-walking monkey on an infinite grid so every banana cell lies on its path, minimizing total steps walked.	Medium7	GeometryImplementation+2	No attempts yet	1s	128 MB	Judgeable
ZonesA diamond-shaped zone grows by extending one of four sides each step; output how many zones border each zone.	Medium7	ImplementationGeometry+1	No attempts yet	1s	128 MB	Judgeable
SegmentsGiven N vertical segments at increasing x, pick A on segment 1 and B on segment N uniformly; find the probability that chord AB crosses every segment.	Medium7	GeometryProbability+1	No attempts yet	0.5s	256 MB	Judgeable
Two BallsTwo balls move on a grid for T seconds with different random rules; compute the probability they collide, to 4 decimals.	Medium7	ProbabilityDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
StickersParse a comma-separated list of sticker numbers and ranges with leading zeros, deduplicate, then output the shortest valid representation with fewest commas.	Medium7	StringImplementation+2	No attempts yet	0.5s	256 MB	Judgeable
Happy sequenceGiven a non-happy sequence, count and list every single-element replacement that makes all adjacent absolute differences exactly the set 1..N-1.	Medium7	ArrayHash map+1	No attempts yet	1.5s	256 MB	Judgeable
MajstorChoose a prerequisite-closed set of jobs that maximizes total fee divided by total hours, with the quotient floored.	Medium7	GreedySorting+2	No attempts yet	3s	128 MB	Judgeable
Safe road systemDelete the fewest road characters so every remaining road is connected to at least two neighbours under the given adjacency rules.	Medium7	GraphBacktracking+1	No attempts yet	1s	64 MB	Judgeable
Adjacent Product GameChoose a subsequence of the given numbers to maximize the sum of products of adjacent chosen pairs.	Medium7	Dynamic programmingGreedy	No attempts yet	1s	64 MB	Judgeable
RivaFind two points on a left-to-right non-self-intersecting polyline whose allowed chord length is within L and maximizes the area between the chord and the polyline above it.	Medium7	GeometryTwo pointers+1	No attempts yet	2s	64 MB	Judgeable
ChemistryBalance a chemical equation by finding integer coefficients for its summands that satisfy the given uniqueness rule.	Medium7	MathNumber theory+1	No attempts yet	1s	64 MB	Judgeable
Cake deliveryGiven a directed graph where every village must be reachable from village 1, find the minimum number of walks starting at village 1 that together cover all vertices.	Medium7	GraphDynamic programming+2	No attempts yet	1s	64 MB	Judgeable
Team BuildingCount pairs of K-cow teams, one from each farmer, such that after sorting both teams John's cow beats Paul's in every paired rank, modulo 1000000009.	Medium7	SortingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Lasers and MirrorsGiven a laser, a barn, and up to 100,000 posts, find the fewest posts to mount mirrors on so the beam travels from laser to barn.	Medium7	GraphBFS+1	No attempts yet	2s	512 MB	Judgeable
Tree and PrimesIn a tree, count pairs of nodes whose path length is prime, and output the probability as a reduced fraction.	Medium7	TreeDFS+1	No attempts yet	3s	512 MB	Judgeable
Arranging HeapsDivide N ordered mining points into K groups, each group merging into one heap at its last point, minimizing total weighted distance moved.	Medium7	Dynamic programmingDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Christmas EveGiven n weighted warehouses on a line, choose k of them as teleporter sites so that moving every other warehouse's presents into a chosen site gives the least total weighted distance.	Medium7	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
MicroRNA RankingGiven k permutations of n items, find a permutation where every earlier item beats the later one in at least half the rankings, choosing the lexicographically smallest such permutation.	Medium7	GraphTopological sort+2	No attempts yet	2s	512 MB	Judgeable
Explosion at CafebazaarA directed multigraph alternates send and receive rounds from an initial 1-bit packet; count the starting switches whose bit makes some buffer grow without bound.	Medium7	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Linear GalaxyGiven 2^n + 1 points on a line, choose 2^(n-1) + 1 of them so that the minimum gap around their cyclic order is as large as possible.	Medium7	SortingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Blocks&BallsGiven a container with fixed blocks and balls inside, find the water level where water volume v fills the region below that height.	Medium7	Binary searchGeometry+2	No attempts yet	2s	512 MB	Judgeable
Sunday CodingCount the distinct sequences of room-winner ranks obtainable when R rooms each hold S contestants with all ranks distinct.	Medium7	CombinatoricsDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Smallest Square 1Given N points, find the smallest axis-aligned square with integer vertices that strictly contains at least N-2 of the points, and output its area.	Medium7	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Smallest Square 2Given N lattice points, choose an axis-aligned square with lattice corners containing at least K points strictly inside and minimize its area.	Medium7	Binary searchSorting+2	No attempts yet	2s	512 MB	Judgeable
Task ProcessingEach task has a day window and a list of durations by start day; pick a subset and an order to finish as many tasks in their windows as possible.	Medium7	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Proving PropositionsChoose directed edges so all N propositions become mutually reachable, minimizing the difference between the hardest and easiest chosen proof difficulties.	Medium7	GraphTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
ProficiencyGiven two counters with geometric service times, find the probability that all L1 people finish before all L2 people do.	Medium7	ProbabilityDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Cutting TreesEach day cut one of n trees to collect its current length, and every tree regrows by A_i nightly; maximize total wood over n days.	Medium7	GreedySorting+1	No attempts yet	2s	512 MB	Judgeable
WolvesCount subsets of N sections, each holding at most one wolf, such that every given interval contains at least one chosen section, modulo 1e9+7.	Medium7	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable