Problems

Pick a problem and write your solution in the built-in editor. The judge runs it against real test cases while you watch, and the wider archive is open to read whenever you like.

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Total results21,380 problems

Royal BallHard9
Graph, Union-find +1No attempts yetTime limit5sMemory limit1024 MB
Judgeable
A very complicated testHard9
Tree, DFS +1No attempts yetTime limit3sMemory limit1024 MB
Judgeable
Fibonacci Digit CountHard9
Math, Dynamic programming +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
f and gHard10
Math, Combinatorics +2No attempts yetTime limit3sMemory limit512 MB
Judgeable
Find Marble Positions and VelocitiesHard10
Math, Combinatorics +2No attempts yetTime limit2sMemory limit128 MB
Judgeable
Tree and Queries 20Hard10
Tree, Segment tree +1No attempts yetTime limit5sMemory limit512 MB
Judgeable
Coalescing ContinentsHard10
Brute force, Math +2No attempts yetTime limit1sMemory limit128 MB
Judgeable
CubesHard10
Combinatorics, Math +2No attempts yetTime limit1sMemory limit128 MB
Judgeable
GeneratorHard10
Implementation, String +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
LogoHard10
Dynamic programming, Bit manipulation +2No attempts yetTime limit1sMemory limit128 MB
Judgeable
String Palindrome QueriesHard10
String, String matching +1No attempts yetTime limit2sMemory limit256 MB
Judgeable
Suneung FractionsHard10
Math, Number theory +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
RobotsHard10
Implementation, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
HyperrectangleHard10
Math, Divide and conquer +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Natural ParkHard10
Graph, BFS +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Dungeon 2Hard10
Graph, BFS +2No attempts yetTime limit1sMemory limit256 MB
Judgeable
Shadow CompanionHard10
Simulation, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Delightful (Easy)Hard10
Implementation, Simulation +2No attempts yetTime limit1sMemory limit512 MB
Judgeable
Xorshift64Hard10
Math, Bit manipulation +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
No Description 2Hard10
ImplementationNo attempts yetTime limit2sMemory limit512 MB
Judgeable
HQ0-9+-INCOMPUTABLE?!Hard10
String, Simulation +2No attempts yetTime limit1sMemory limit1024 MB
Judgeable
Beautiful AutomataHard10
Graph, Topological sort +2No attempts yetTime limit2sMemory limit512 MB
Judgeable
Mysterious … HostHard10
Combinatorics, Math +2No attempts yetTime limit2sMemory limit256 MB
Judgeable
Fast BridgesHard10
Shortest path, Sorting +2No attempts yetTime limit2sMemory limit1024 MB
Judgeable
Rational ApproximationUnrated
Not classified yetNo attempts yetTime limit1sMemory limit128 MB
Judgeable
ZuUnrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Star Pattern 15Unrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Star Pattern - 16Unrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Printing Stars 20Unrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Star pattern 22Unrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Project Team Vacation ScheduleUnrated
Not classified yetNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Maximum edge cost on a tree pathUnrated
Not classified yetNo attempts yetTime limit2sMemory limit512 MB
Judgeable
Distinct weights on a tree pathUnrated
Not classified yetNo attempts yetTime limit2sMemory limit512 MB
Judgeable
City DevelopmentUnrated
Not classified yetNo attempts yetTime limit3sMemory limit512 MB
Judgeable
Distributing the TreasureUnrated
Not classified yetNo attempts yetTime limit4sMemory limit1024 MB
Judgeable
PostmanUnrated
Not classified yetNo attempts yetTime limit8sMemory limit256 MB
Judgeable
Amusement ArcadeUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Special PrizeUnrated
Not classified yetNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
Changing CardsUnrated
Not classified yetNo attempts yetTime limit1.5sMemory limit1024 MB
Judgeable
DigestaUnrated
Not classified yetNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Curious ShiftUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
KingdomUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
AuthorityUnrated
Not classified yetNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
Keep in TouchUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Make an XUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Make an X (Hard)Unrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Predicting the grassUnrated
Not classified yetNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
String TowerUnrated
Not classified yetNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Two-dimensional arrayUnrated
Not classified yetNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Chocolate and the King GameUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Odd/Even StringsUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Check ListUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
SGA PresidentUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
I Love You, YonseiUnrated
Not classified yetNo attempts yetTime limit1.885sMemory limit1024 MB
Judgeable
Interplanetary Study MeetingUnrated
Not classified yetNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
Unbroken Spirit 3Unrated
Not classified yetNo attempts yetTime limit6sMemory limit1024 MB
Judgeable
Vertical CalendarUnrated
Not classified yetNo attempts yetTime limit1sMemory limit512 MB
Judgeable
Alternating AlgorithmUnrated
Not classified yetNo attempts yetTime limit7sMemory limit1024 MB
Judgeable
Big Data? Information Security!Unrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
Vigenère Cipher DecryptionUnrated
Not classified yetNo attempts yetTime limit1.5sMemory limit256 MB
Judgeable
Bank Robbery 2Unrated
Not classified yetNo attempts yetTime limit1sMemory limit256 MB
Judgeable
A Prickly Problem: Black EditionUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
AdriaUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
DominoUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
FrizuraUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
GameUnrated
Not classified yetNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
Students and MentorsUnrated
Not classified yetNo attempts yetTime limitNot setMemory limit1024 MB
Judgeable
Pizza DeliveryUnrated
Not classified yetNo attempts yetTime limit20sMemory limit1024 MB
Judgeable
Happy SubarraysUnrated
Not classified yetNo attempts yetTime limit25sMemory limit1024 MB
Judgeable
Running in CirclesUnrated
Not classified yetNo attempts yetTime limitNot setMemory limit1024 MB
Judgeable
Magical Well of LiliesUnrated
Not classified yetNo attempts yetTime limit15sMemory limit1024 MB
Judgeable
ElectricityUnrated
Not classified yetNo attempts yetTime limit40sMemory limit1024 MB
Judgeable
1-Player ConcentrationUnrated
Not classified yetNo attempts yetTime limit2sMemory limit1024 MB
Judgeable
Greatest common divisorUnrated
Not classified yetNo attempts yetTime limit8sMemory limit1024 MB
Judgeable
PINUnrated
Not classified yetNo attempts yetTime limit0.2sMemory limit1024 MB
Judgeable
RykiUnrated
Not classified yetNo attempts yetTime limit8sMemory limit1024 MB
Judgeable
SkwarkiUnrated
Not classified yetNo attempts yetTime limit3sMemory limit256 MB
Judgeable
Alps Cable CarUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
ToysUnrated
Not classified yetNo attempts yetTime limit1sMemory limit1024 MB
Judgeable
Concurrent ProgrammingUnrated
Not classified yetNo attempts yetTime limit9sMemory limit1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Royal BallOn an n by n grid whose cells flip state, find after each flip the maximum number of hoop throws between performers in the same row or column.	Hard9	GraphUnion-find+1	No attempts yet	5s	1024 MB	Judgeable
A very complicated testGiven two BSTs on keys 1 to n, find the fewest rotations that turn one into the other without dropping a subtree, modulo 1e9+7, or -1.	Hard9	TreeDFS+1	No attempts yet	3s	1024 MB	Judgeable
Fibonacci Digit CountCount occurrences of the substring "11" within the first N characters of the infinite string formed by writing 1, 2, 3, ... in Fibonacci (Zeckendorf) representation.	Hard9	MathDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
f and gCompute g(T,k)=sum_{x=0}^{T} sum_i (x+a_i)^k mod 1e9+7 for every k from 0 to K, given N up to 1e5, K up to 5e4, T up to 1e18.	Hard10	MathCombinatorics+2	No attempts yet	3s	512 MB	Judgeable
Find Marble Positions and VelocitiesReconstruct each marble's starting x-coordinate and constant velocity from N+1 unordered snapshots of N linearly moving marbles.	Hard10	MathCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Tree and Queries 20Maintain a dynamic forest with link/cut and weighted edges, supporting toggling a vertex weight and querying the minimum weighted sum of tree distances from any vertex, with encrypted vertex indices.	Hard10	TreeSegment tree+1	No attempts yet	5s	512 MB	Judgeable
Coalescing ContinentsGiven K rectangles with total area 25 on a 20x20 grid, decide if they can be translated to tile a square, and find the minimum total moves.	Hard10	Brute forceMath+2	No attempts yet	1s	128 MB	Judgeable
CubesCount the orbits of general-purpose chip placements on cube faces under face rotations and cube rearrangement, given a fixed pattern of encoding chips.	Hard10	CombinatoricsMath+2	No attempts yet	1s	128 MB	Judgeable
GeneratorRead an index 0 to 10 and output the exact contents of the matching recovered file gen_i.out from the archive.	Hard10	ImplementationString+2	No attempts yet	2s	256 MB	Judgeable
LogoGiven up to five polyomino patch shapes (each a subset of a 3x3 grid, flippable and rotatable) and up to three grid designs up to 55x5, decide if each design can be tiled exactly by non-overlapping patches and find the minimum patch count, or report NIE.	Hard10	Dynamic programmingBit manipulation+2	No attempts yet	1s	128 MB	Judgeable
String Palindrome QueriesMaintain a lowercase string under block moves, reversals, and single-character insertions, answering after each change whether a given substring reads the same forwards and backwards.	Hard10	StringString matching+1	No attempts yet	2s	256 MB	Judgeable
Suneung FractionsGiven x in [A,B] and y in [C,D] up to 1e12, count pairs where the reduced numerator and denominator sum to at most 999.	Hard10	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
RobotsDesign two robots' instruction tables so they classify a binary string as fine or coarse from its middle third's A and B counts, using four-bit memories, exact-then-wildcard dispatch, and 1000n steps.	Hard10	ImplementationBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
HyperrectangleCompute d!V for the volume of a box with side lengths li where sum xi <= s via characteristic polynomials and Lenstra inclusion of capped orthants.	Hard10	MathDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Natural ParkReconstruct the exact edge set of a sparse connected graph with degree at most 7 using at most 45,000 connectivity queries over chosen subsets.	Hard10	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Dungeon 2Explore an unknown connected graph through a move-and-color oracle and report, for each i, how many room pairs have shortest-path distance exactly i.	Hard10	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
Shadow CompanionConstruct a fixed program over a bit tape with a shadow that transforms every input n < 2^10 into n squared.	Hard10	SimulationBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Delightful (Easy)Write a program of at most 100 commands for a ternary computer with 26 40-trit registers that computes the length of the longest non-decreasing prefix of the input in register X and leaves the answer in Y.	Hard10	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Xorshift64Given a start value x, find the 1-based index at which the target value t first appears in the xorshift64 sequence.	Hard10	MathBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
No Description 2The statement gives no task, no input format, and no examples, so nothing about the required algorithm can be determined.	Hard10	Implementation	No attempts yet	2s	512 MB	Judgeable
HQ0-9+-INCOMPUTABLE?!Construct an HQ0-9+-INCOMPUTABLE?! program of at most 10000 commands whose final buffer equals a given target string.	Hard10	StringSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Beautiful AutomataGiven a DAG, find the lexicographically smallest string whose suffix automaton is exactly this graph, or report -1 if none exists.	Hard10	GraphTopological sort+2	No attempts yet	2s	512 MB	Judgeable
Mysterious … HostFor each n up to N, find the minimum number of permutations needed so that every permutation of order n shares its answers to all consecutive-segment queries with one of them, modulo a prime P.	Hard10	CombinatoricsMath+2	No attempts yet	2s	256 MB	Judgeable
Fast BridgesGiven a k by k grid plus n bridges that cut travel time, find the sum of shortest distances over all cell pairs modulo 998244353.	Hard10	Shortest pathSorting+2	No attempts yet	2s	1024 MB	Judgeable
Rational Approximation	Unrated	Not classified yet	No attempts yet	1s	128 MB	Judgeable
Zu	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
Star Pattern 15	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
Star Pattern - 16	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
Printing Stars 20	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
Star pattern 22	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
Project Team Vacation Schedule	Unrated	Not classified yet	No attempts yet	1s	512 MB	Judgeable
Maximum edge cost on a tree path	Unrated	Not classified yet	No attempts yet	2s	512 MB	Judgeable
Distinct weights on a tree path	Unrated	Not classified yet	No attempts yet	2s	512 MB	Judgeable
City Development	Unrated	Not classified yet	No attempts yet	3s	512 MB	Judgeable
Distributing the Treasure	Unrated	Not classified yet	No attempts yet	4s	1024 MB	Judgeable
Postman	Unrated	Not classified yet	No attempts yet	8s	256 MB	Judgeable
Amusement Arcade	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Special Prize	Unrated	Not classified yet	No attempts yet	2s	1024 MB	Judgeable
Changing Cards	Unrated	Not classified yet	No attempts yet	1.5s	1024 MB	Judgeable
Digesta	Unrated	Not classified yet	No attempts yet	1s	512 MB	Judgeable
Curious Shift	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Kingdom	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Authority	Unrated	Not classified yet	No attempts yet	2s	1024 MB	Judgeable
Keep in Touch	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Make an X	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Make an X (Hard)	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Predicting the grass	Unrated	Not classified yet	No attempts yet	2s	1024 MB	Judgeable
String Tower	Unrated	Not classified yet	No attempts yet	1s	512 MB	Judgeable
Two-dimensional array	Unrated	Not classified yet	No attempts yet	1s	512 MB	Judgeable
Chocolate and the King Game	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Odd/Even Strings	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Check List	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
SGA President	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
I Love You, Yonsei	Unrated	Not classified yet	No attempts yet	1.885s	1024 MB	Judgeable
Interplanetary Study Meeting	Unrated	Not classified yet	No attempts yet	2s	1024 MB	Judgeable
Unbroken Spirit 3	Unrated	Not classified yet	No attempts yet	6s	1024 MB	Judgeable
Vertical Calendar	Unrated	Not classified yet	No attempts yet	1s	512 MB	Judgeable
Alternating Algorithm	Unrated	Not classified yet	No attempts yet	7s	1024 MB	Judgeable
Big Data? Information Security!	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
Vigenère Cipher Decryption	Unrated	Not classified yet	No attempts yet	1.5s	256 MB	Judgeable
Bank Robbery 2	Unrated	Not classified yet	No attempts yet	1s	256 MB	Judgeable
A Prickly Problem: Black Edition	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Adria	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Domino	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Frizura	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Game	Unrated	Not classified yet	No attempts yet	2s	1024 MB	Judgeable
Students and Mentors	Unrated	Not classified yet	No attempts yet	Not set	1024 MB	Judgeable
Pizza Delivery	Unrated	Not classified yet	No attempts yet	20s	1024 MB	Judgeable
Happy Subarrays	Unrated	Not classified yet	No attempts yet	25s	1024 MB	Judgeable
Running in Circles	Unrated	Not classified yet	No attempts yet	Not set	1024 MB	Judgeable
Magical Well of Lilies	Unrated	Not classified yet	No attempts yet	15s	1024 MB	Judgeable
Electricity	Unrated	Not classified yet	No attempts yet	40s	1024 MB	Judgeable
1-Player Concentration	Unrated	Not classified yet	No attempts yet	2s	1024 MB	Judgeable
Greatest common divisor	Unrated	Not classified yet	No attempts yet	8s	1024 MB	Judgeable
PIN	Unrated	Not classified yet	No attempts yet	0.2s	1024 MB	Judgeable
Ryki	Unrated	Not classified yet	No attempts yet	8s	1024 MB	Judgeable
Skwarki	Unrated	Not classified yet	No attempts yet	3s	256 MB	Judgeable
Alps Cable Car	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Toys	Unrated	Not classified yet	No attempts yet	1s	1024 MB	Judgeable
Concurrent Programming	Unrated	Not classified yet	No attempts yet	9s	1024 MB	Judgeable