Problems

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Total results29,250 problems

Arc of Triumph 10
Hard8
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Feeding Geese
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Wrong Queue
Hard8
Array, Binary search+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Zeus
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Finding Bridges
Hard8
Graph, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Gadget Construction
Hard8
Geometry, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Introversion
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Distance Permutation
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Knight Game
Hard8
Game theory, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gacha 101
Hard8
Probability, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Convex Polygon MST
Hard8
Graph, Minimum spanning tree+1
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Odd Trip Plans
Hard8
Union-find, Divide and conquer+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Integers
Hard8
Bit manipulation, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pool
Hard8
Probability, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Vegetables
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Majority Element in Concatenated Sequences
Hard8
Segment tree, Stack+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Challenge NPC
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Quadratic Integer Program
Hard8
Dynamic programming, Brute force+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Depth First Search
Hard8
Tree, DFS+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Trade
Hard8
Shortest path, Tree+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Reversi
Hard8
Game theory, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Aperiodic Appointments
Hard8
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Factor-Full Tree
Hard8
Number theory, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Perfect Quadrants
Hard8
Sliding window, Hash map+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Rigged Lottery
Hard8
String, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Float Lanterns
Hard8
Sliding window, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Why Hobawoo Was Late for School 6
Hard8
Dynamic programming, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Analyzing Contracts
Hard8
Geometry, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Health in Hazard
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
3.5s
Memory limit
1024 MB
Judgeable
International Irregularities
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Quadrat Search (Hard)
Hard8
Segment tree, Hash map+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
International Travel
Hard8
Geometry, Brute force
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hamster
Hard8
Graph, Union-find+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Colorful Village
Hard8
Tree, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Intersegment Activation
Hard8
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Loops
Hard8
Matrix, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Permutation and Operations
Hard8
Array, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Royal Problem
Hard8
Graph, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
A Little Substring Problem
Hard8
String matching, Trie+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Mostovi
Hard8
Graph, DFS+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Plane stretching
Hard8
Geometry, Two pointers+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Air Reform
Hard8
Graph, Minimum spanning tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Making a Constellation
Hard8
Tree, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Starry Night (Hard)
Hard8
Prefix sum, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Track Assembly
Hard8
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Median Mountain Range
Hard8
Array, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Reality Show
Hard8
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Instant Noodles
Hard8
Hash map, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hosting KCPC
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Secret Swap
Hard8
Union-find, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dima and the Array
Hard8
Array, Segment tree
No attempts yet
Time limit
6.5s
Memory limit
1024 MB
Judgeable
Swaps in a Permutation
Hard8
Dynamic programming, Union-find+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Not So Distant Strings
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Random Walks in a Big City
Hard8
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Road to the Olympiad
Hard8
Graph, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Astronomy
Hard8
Geometry, Math+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Turn on the lights, close the doors!
Hard8
Graph, DFS
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Efficient Evaluation
Hard8
Segment tree, Simulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Abstracts
Hard8
String, String matching
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
New Year and Rectangle
Hard8
Binary search, Implementation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Yet Another Coin Problem
Hard8
Dynamic programming, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Paint the Roads
Hard8
Graph, Implementation
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Find the Disobedient Child
Hard8
Math, Binary search
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Zip-line
Hard8
Dynamic programming, Binary search+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Batman Returns
Hard8
Divide and conquer, Array+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Speedy Turtle
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Chapaev on a Tree
Hard8
Tree, Game theory+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Farm
Hard8
Geometry, Graph+1
No attempts yet
Time limit
0.7s
Memory limit
2048 MB
Judgeable
K-Lottery
Hard8
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Walk Swapping
Hard8
Array, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Hanyang Cherry Picking Contest
Hard8
Tree, Game theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pipelined
Hard8
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Movable Type Graph
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Pay2Win
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Chair Dance
Hard8
Simulation, Number theory+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Galaxy Quest
Hard8
Shortest path, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
NL-Queen (mod N)
Hard8
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Queens' Rye Cafe
Hard8
Number theory, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
N-Queen (Area)
Hard8
Backtracking, Geometry+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Coffee Milk
Hard8
Math, Geometry+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Rank Promotion
Hard8
Prefix sum, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Ferris Wheel
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Task Assignment to Two Employees
Hard8
Graph, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Liquid Distribution
Hard8
Geometry, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Do It Yourself?
Hard8
Tree, Dynamic programming
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Probing the Disk
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sequence and Queries 44
Hard8
Segment tree, Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Attendance
Hard8
Intervals, Greedy+1
No attempts yet
Time limit
8s
Memory limit
128 MB
Judgeable
Drying Laundry
Hard8
Dynamic programming, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Labelled Paths
Hard8
Dynamic programming, Topological sort+2
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
\sqrt{f}(x)
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Derivatives of Polynomials and Remainders
Hard8
Math, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Split the SSHS 2
Hard8
Graph, DFS+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Zoom
Hard8
Segment tree, Simulation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Coloring Cards 2
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Train Scheduling
Hard8
Sorting, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bovine Acrobatics
Hard8
Sorting, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candy Cane Feast
Hard8
Segment tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Farmer John Actually Farms
Hard8
Binary search, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Taking Photos
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Arc of Triumph 10Build a given stone arc cross-section with the fewest temporary wooden blocks, printing the place and remove steps so every block stays stable.	Hard8	SimulationImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Feeding GeeseChoose which geese to feed, given each goose's waiting window and speed level, to maximize the total cuteness of the fed geese.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	5s	1024 MB	Judgeable
Wrong QueueEach pop removes the elements at fixed positions A_1 to A_N at once, and for each query the task asks for the value at index x after D pops.	Hard8	ArrayBinary search+1	No attempts yet	3s	1024 MB	Judgeable
ZeusGiven a connected weighted graph with treewidth at most 2, compute the sum of shortest-path distances over all pairs of vertices.	Hard8	GraphShortest path+1	No attempts yet	12s	1024 MB	Judgeable
Finding BridgesGiven a simple undirected graph and a sequence of edge removals, report the number of bridges left after each removal.	Hard8	GraphDFS+2	No attempts yet	3s	1024 MB	Judgeable
Gadget ConstructionCount subsets of at least 4 cogs whose convex hull alternates colors around its vertices, with interior cogs of any color, modulo 1e9+7.	Hard8	GeometryDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
IntroversionGiven a row of 2n slots with some dishes fixed, count the ways to fill the empty slots so each type appears twice and no two equal types are adjacent, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	3s	1024 MB	Judgeable
Distance PermutationGiven K, count the permutations of 1 to N that the walk can produce, where the first element lies between L and R.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	5s	1024 MB	Judgeable
Knight GameGiven a knight on an H by W board, decide whether Alice or Bob wins when both alternately move the knight to unvisited squares.	Hard8	Game theoryGraph+1	No attempts yet	2s	1024 MB	Judgeable
Gacha 101Balls labeled 1 to N are drawn uniformly at random, and the task asks for the probability that the string s ever contains 101 as a substring, modulo 998244353.	Hard8	ProbabilityCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Convex Polygon MSTGiven a convex polygon's vertices, find the spanning tree whose edges, weighted by squared Euclidean length, have the maximum total weight.	Hard8	GraphMinimum spanning tree+1	No attempts yet	7s	1024 MB	Judgeable
Odd Trip PlansGiven an undirected graph whose edges are toggled by queries, answer for each query whether a walk from x to y visits every airport an odd number of times.	Hard8	Union-findDivide and conquer+1	No attempts yet	3s	1024 MB	Judgeable
IntegersProcess n operations that add a·2^b to an integer x, or report the bit of x at position k, while x stays non-negative.	Hard8	Bit manipulationSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
PoolFind the probability that the largest all-safe rectangle touching the bottom of an N by 1001 grid is exactly K cells, given safe probability x/y.	Hard8	ProbabilityDynamic programming+1	No attempts yet	3s	1024 MB	Judgeable
VegetablesFor each query p, find the maximum profit over p days when at most m units can be sold per day from vegetables that spoil.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	1024 MB	Judgeable
Majority Element in Concatenated SequencesMaintain n sequences under push, pop, concatenation, and merge operations, and report the strict majority element of each concatenation.	Hard8	Segment treeStack+1	No attempts yet	1.5s	1024 MB	Judgeable
Challenge NPCGiven rooted trees G and H with \|H\| <= \|G\| <= \|H\| + k, decide whether deleting nodes of G (never the root) can leave a connected tree isomorphic to H.	Hard8	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Quadratic Integer ProgramFor each query of weights, find the maximum-weight integer sequence that stays within given intervals and pairwise difference limits, and print that weight.	Hard8	Dynamic programmingBrute force+1	No attempts yet	2s	1024 MB	Judgeable
Depth First SearchCount subsets of the m extra edges so that tree T, plus the chosen edges, is a DFS tree from one of the k special vertices.	Hard8	TreeDFS+2	No attempts yet	6s	1024 MB	Judgeable
TradeSum all pairwise shortest distances in a complete binary tree with upward edges and m ancestor-to-descendant edges, modulo 998244353.	Hard8	Shortest pathTree+1	No attempts yet	1.5s	1024 MB	Judgeable
ReversiFor each N by M board, decide whether the second player with 1x1 stones wins, loses, or draws against a first player placing 2x1 dominoes under optimal play.	Hard8	Game theoryCombinatorics+1	No attempts yet	1s	512 MB	Judgeable
Aperiodic AppointmentsCount the ones in a binary string of length N, where each new bit is 1 exactly when the string ends in a K-th power of some nonempty block.	Hard8	StringString matching+1	No attempts yet	1s	1024 MB	Judgeable
Factor-Full TreeGiven a rooted tree of up to 60 vertices, assign each vertex a number up to 10^18 so that x_v divides x_u exactly when v is an ancestor of u.	Hard8	Number theoryTree+1	No attempts yet	1s	1024 MB	Judgeable
Perfect QuadrantsCount grid points (x, y) whose lower-left quadrant contains exactly c_i points of each set P_i, with no set point on the quadrant boundary.	Hard8	Sliding windowHash map+2	No attempts yet	4s	1024 MB	Judgeable
Rigged LotteryGiven k, c, and a ticket of length k, find the shortest sequence over 1 to c that contains every length-k sequence as a subsequence except that ticket.	Hard8	StringCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Float LanternsPick S consecutive lanterns and count pairs where a later-released lantern rises faster than an earlier one; output the maximum count over all windows.	Hard8	Sliding windowDivide and conquer+1	No attempts yet	1s	1024 MB	Judgeable
Why Hobawoo Was Late for School 6Shrink an array of N non-negative integers to exactly M elements using four XOR-merge spells, maximizing the sum of the final elements.	Hard8	Dynamic programmingBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Analyzing ContractsClients are added with an end day and daily revenue, and each supplier query asks for the maximum profit from matching an available client to that supplier.	Hard8	GeometrySegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Health in HazardGiven N half-plane cuts through a plane with a den at the origin, find the first cut after which no point on the circle of radius D is reachable.	Hard8	GeometryBinary search+1	No attempts yet	3.5s	1024 MB	Judgeable
International IrregularitiesGiven countries with r-values and quarantine times, answer each query with the minimum days to travel from a start country to a destination.	Hard8	Shortest pathGraph+1	No attempts yet	3s	1024 MB	Judgeable
Quadrat Search (Hard)Given an array with range-delete queries (set cells to zero) and range queries that count occurrences of a value, answer each count query online in order.	Hard8	Segment treeHash map+2	No attempts yet	1.5s	1024 MB	Judgeable
International TravelGiven three pin circles for a plug and three hole circles for a socket, decide whether the plug can be rigidly moved so each pin fits a matching hole, with the earth pin fixed.	Hard8	GeometryBrute force	No attempts yet	2s	1024 MB	Judgeable
HamsterGiven M unit wall segments on a grid, find the fewest extra unit segments needed to close a loop that fully encloses Joe.	Hard8	GraphUnion-find+1	No attempts yet	4s	1024 MB	Judgeable
Colorful VillageGiven a tree of 2n houses with each color on two houses, find a connected set of n houses containing one house of each color, or print -1.	Hard8	TreeGraph+1	No attempts yet	2s	1024 MB	Judgeable
Intersegment ActivationInteractive task: flip interval barriers one at a time, reading the visible-cell count after each flip, until every barrier is inactive.	Hard8	Bit manipulationMath+1	No attempts yet	2s	1024 MB	Judgeable
LoopsGiven the loop shape type of each 2x2 square in an n by m grid, construct a grid of distinct integers 1 to nm that produces those shapes.	Hard8	MatrixGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Permutation and OperationsGiven a permutation of 1 to N, decide whether at most 4 adjacent swaps or range-clamp operations can make every element equal, and print them.	Hard8	ArrayImplementation	No attempts yet	1s	1024 MB	Judgeable
Royal ProblemGiven a directed graph with XOR-weighted edges, find the XOR of the XORs of all walks from a to b, or report -1 if infinitely many walks have nonzero XOR.	Hard8	GraphBit manipulation+2	No attempts yet	3s	1024 MB	Judgeable
A Little Substring ProblemGiven a text t and a set of distinct patterns, answer queries by counting how many pattern occurrences lie fully inside t[l..r].	Hard8	String matchingTrie+1	No attempts yet	4s	1024 MB	Judgeable
MostoviCount the edges (a, b) such that deleting both endpoints a and b leaves the remaining n - 2 nodes disconnected.	Hard8	GraphDFS+1	No attempts yet	3s	1024 MB	Judgeable
Plane stretchingGiven n points, for each scale factor alpha, multiply every x-coordinate by alpha and output the largest distance between any two points.	Hard8	GeometryTwo pointers+1	No attempts yet	10s	1024 MB	Judgeable
Air ReformGiven a connected weighted graph, find for each edge the cheapest route between its endpoints in the complement graph, where a route costs its largest edge.	Hard8	GraphMinimum spanning tree+1	No attempts yet	2s	1024 MB	Judgeable
Making a ConstellationAttach N tree decorations in order, each red root to the shallowest unconnected blue star, and find the minimum possible maximum depth.	Hard8	TreeGreedy+1	No attempts yet	1s	512 MB	Judgeable
Starry Night (Hard)Given N stars with brightness that fades by Manhattan distance, find the total brightness summed over every cell in a given rectangle.	Hard8	Prefix sumMath+1	No attempts yet	1s	512 MB	Judgeable
Track AssemblyGiven a tree, each query removes one edge and may re-add it anywhere, asking for the longest simple path the train can walk in the new tree.	Hard8	TreeDFS+1	No attempts yet	1s	1024 MB	Judgeable
Median Mountain RangeRepeatedly replace each inner height with the median of it and its two neighbors, and count the rounds until nothing changes.	Hard8	ArrayGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Reality ShowPick a subset of candidates that obeys the record rule, then maximize the on-stage fight revenue minus the recruitment costs.	Hard8	Dynamic programmingBit manipulation	No attempts yet	2s	1024 MB	Judgeable
Instant NoodlesGiven a bipartite graph with weights on the right side, find the gcd of the sums of right-vertex values covered by each nonempty subset of left vertices.	Hard8	Hash mapNumber theory	No attempts yet	2s	1024 MB	Judgeable
Hosting KCPCGiven three point sets, sum over every triple (one point from each set) the squared side lengths plus or minus twice the signed triangle area, modulo 1e9+7.	Hard8	GeometrySorting+1	No attempts yet	1s	1024 MB	Judgeable
Secret SwapCount the distinct final card arrangements reachable by swapping two cards whose values have bitwise AND at most K/2, modulo 1e9+7.	Hard8	Union-findBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Dima and the ArrayGiven an array of up to 500,000 integers, answer the MEX of any subarray [l, r] while processing point updates to single elements.	Hard8	ArraySegment tree	No attempts yet	6.5s	1024 MB	Judgeable
Swaps in a PermutationGiven a permutation and a set of allowed position swaps, find the maximum LIS length reachable by applying any number of these swaps.	Hard8	Dynamic programmingUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Not So Distant StringsGiven a digit string s and k, output the k-th length-n digit string when all strings are sorted by digit distance to s, then lexicographically.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Random Walks in a Big CityGiven a connected road network, find the fewest minutes a student is guaranteed to reach home when random turns are adversarial, or -1 if they can wander forever.	Hard8	GraphBFS+1	No attempts yet	5s	1024 MB	Judgeable
Road to the OlympiadGiven a graph where flights are added and removed, find the cheapest route between two cities using at most two flights.	Hard8	GraphHash map+1	No attempts yet	2s	1024 MB	Judgeable
AstronomyGiven 2n star points, find an integer point off all stars where every line through it holds either zero or exactly two stars, or report No.	Hard8	GeometryMath+1	No attempts yet	5s	1024 MB	Judgeable
Turn on the lights, close the doors!Escape an unknown maze of up to 50 rooms by switching lights and using one-time door locks so that every room is lit and all but one are locked.	Hard8	GraphDFS	No attempts yet	3s	1024 MB	Judgeable
Efficient EvaluationGiven a queue of m tests and n moves that each remove every other test in a position range, report the smallest and largest original index removed per move.	Hard8	Segment treeSimulation+1	No attempts yet	2s	1024 MB	Judgeable
AbstractsFor each article, find the shortest substring that appears in no other article, breaking ties by lexicographic order, or report that none exists.	Hard8	StringString matching	No attempts yet	3s	1024 MB	Judgeable
New Year and RectangleLocate a hidden axis-aligned rectangle on an n by n grid using at most q count queries over an interactive judge. Standard binary search on edges with a count oracle.	Hard8	Binary searchImplementation+1	No attempts yet	3s	1024 MB	Judgeable
Yet Another Coin ProblemGiven N coin types with counts and values, decide whether some choice of coins sums to exactly X, and print the number of each coin type used if so.	Hard8	Dynamic programmingNumber theory	No attempts yet	2s	1024 MB	Judgeable
Paint the RoadsGiven a graph with colored roads, decide whether a walk can leave each building with its target color, and output such a walk within 1,000,000 visits if one exists.	Hard8	GraphImplementation	No attempts yet	1.5s	1024 MB	Judgeable
Find the Disobedient ChildGiven N children who each returned up to K emeralds over several days, find the fewest days needed to identify the one child who sold all of theirs.	Hard8	MathBinary search	No attempts yet	3s	1024 MB	Judgeable
Zip-lineFor each assumption that one tree has a new height, find the longest strictly increasing subsequence of the trees after that single change.	Hard8	Dynamic programmingBinary search+1	No attempts yet	3s	1024 MB	Judgeable
Batman ReturnsGiven an array of heights and many range queries, find the pair p < q inside each range with h_p < h_q and maximal q - p, or print -1 -1 if none exists.	Hard8	Divide and conquerArray+1	No attempts yet	2.5s	1024 MB	Judgeable
Speedy TurtleFor each card, count the triples (a, b, c) where a down-right path from a to c exists after all cells of B are blocked, and that path does not pass through b.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	1s	1024 MB	Judgeable
Chapaev on a TreeFor each vertex as Root, count the games on its descendants where Marina moves first and flicks checkers toward the root, then report how many she wins.	Hard8	TreeGame theory+2	No attempts yet	2s	1024 MB	Judgeable
FarmGiven a rectilinear farm boundary and pest locations, find the fewest pairwise disjoint axis-aligned rectangles inside the farm that cover every pest.	Hard8	GeometryGraph+1	No attempts yet	0.7s	2048 MB	Judgeable
K-LotteryGiven M permutation tickets of length K, find the earliest window of K consecutive numbers in the sequence whose relative order matches a sold ticket.	Hard8	String matchingString+1	No attempts yet	2s	2048 MB	Judgeable
Walk SwappingGiven initial and final coin arrangements on a cycle, find the fewest swaps along a walk that turns one into the other, or report -1 if impossible.	Hard8	ArrayPrefix sum+1	No attempts yet	1s	2048 MB	Judgeable
Hanyang Cherry Picking ContestTwo players alternately take tree vertices by moving to a child of the last taken vertex, and the task is to find the winner under optimal play.	Hard8	TreeGame theory+1	No attempts yet	1s	1024 MB	Judgeable
PipelinedFind the minimum seconds for N cars, each with stage count s_i, to pass through the slot [0,1) when each car's interval moves by its own length every second.	Hard8	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
Movable Type GraphFind the shortest path from vertex 1 to vertex 2 in graph T, where each graph can embed earlier graphs as sub-blocks with chosen entry and exit vertices.	Hard8	GraphShortest path+1	No attempts yet	1.5s	1024 MB	Judgeable
Pay2WinGiven K zone-swap patterns repeated until a boss with H health is defeated, find the start zone that maximizes the minimum skip cost needed to win.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Chair DancePlayers on n chairs move by +x or *x (mod n) each command, and the shortest clockwise traveler keeps a contested chair; answer who sits on each queried chair.	Hard8	SimulationNumber theory+1	No attempts yet	8s	1024 MB	Judgeable
Galaxy QuestFor each query, find the least fuel needed to fly from planet 1 to a target planet within a time limit, where each highway's fuel cost depends on how long the trip takes.	Hard8	Shortest pathDynamic programming+1	No attempts yet	5s	1024 MB	Judgeable
NL-Queen (mod N)Place N queens on an N by N board whose opposite edges connect, so none attack each other, and print one placement that is not k-linear, or -1 if impossible.	Hard8	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Queens' Rye CafeGiven a fraction a/b in the Farey sequence of order N, find the fraction j positions after it, with N up to 10^18 and j up to 2 times 10^7.	Hard8	Number theoryGreedy+1	No attempts yet	2s	1024 MB	Judgeable
N-Queen (Area)Place N non-attacking queens on an N by N grid warped inside a convex quadrilateral to maximize the total area of the occupied cells.	Hard8	BacktrackingGeometry+1	No attempts yet	1s	1024 MB	Judgeable
Coffee MilkGiven a tetrahedron with integer vertices and N scale factors K, count the lattice points on its surface and inside it for each K, modulo 1003003001.	Hard8	MathGeometry+1	No attempts yet	3s	1024 MB	Judgeable
Rank PromotionGiven n quiz results as Y or N, compute the final rank when a rank rises after any window of at least c quizzes with correct ratio at least p/q, starting from the current rank.	Hard8	Prefix sumDynamic programming+1	No attempts yet	3s	1024 MB	Judgeable
Ferris WheelCount colorings of 2n gondolas on a circle with k colors that allow a non-crossing pairing of same-colored gondolas, modulo 998244353, up to rotation.	Hard8	CombinatoricsMath+1	No attempts yet	6s	1024 MB	Judgeable
Task Assignment to Two EmployeesAssign each of n tasks to one of two employees and pick the order so that total profit, where skill points grow with each completed task, is maximized.	Hard8	GraphDynamic programming	No attempts yet	2s	1024 MB	Judgeable
Liquid DistributionDecide whether pouring the mixed bottles together can produce exactly the amounts of liquids A and B each institute requires.	Hard8	GeometryGraph+1	No attempts yet	2s	1024 MB	Judgeable
Do It Yourself?Each task can be done by its owner or any of the owner's bosses. Find the minimum sum of f_i times (tasks done by i) squared over all employees.	Hard8	TreeDynamic programming	No attempts yet	10s	1024 MB	Judgeable
Probing the DiskFind the integer center and radius of a hidden disk in a 10^5 by 10^5 square by probing with segments and reading the lit chord length.	Hard8	GeometryBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Sequence and Queries 44For each query m k, find the longest subsequence of the first m elements whose longest increasing subsequence has length at most k.	Hard8	Segment treeDynamic programming	No attempts yet	1s	1024 MB	Judgeable
AttendanceAfter each insertion or removal of an interval, print the minimum number of points needed so that every interval on the current list contains at least one point.	Hard8	IntervalsGreedy+1	No attempts yet	8s	128 MB	Judgeable
Drying LaundryEach sheet either hangs on one line (slow time) or spans both lines (fast time). For each line length, find the minimal time to dry all sheets, or report -1.	Hard8	Dynamic programmingSorting+1	No attempts yet	3s	1024 MB	Judgeable
Labelled PathsGiven a DAG whose edge labels are substrings of one string A, find the lexicographically smallest path label from s to every vertex.	Hard8	Dynamic programmingTopological sort+2	No attempts yet	15s	1024 MB	Judgeable
\sqrt{f}(x)Given an integer polynomial f, find a polynomial g with coefficients from -100 to 100 such that g(g(x)) = f(x), or report -1.	Hard8	MathNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Derivatives of Polynomials and RemaindersCount the coefficient sequences c of degree at most n with entries in [a, b] whose k-th derivative has coefficients matching s mod m, and print the lexicographically smallest one.	Hard8	MathNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Split the SSHS 2Count the sets of three buildings such that deleting all roads among them leaves some two buildings unable to reach each other.	Hard8	GraphDFS+1	No attempts yet	1.5s	1024 MB	Judgeable
ZoomMaintain an array under range additions, block copies that repeat a pair of cells, and full replays of past queries, then print range sums modulo 998244353.	Hard8	Segment treeSimulation	No attempts yet	3s	1024 MB	Judgeable
Coloring Cards 2Given the colors of the first row of an N by N grid, sum the number of white patterns over all valid colorings where diagonals match and every row has the same white count.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Train SchedulingSchedule N trains from two stations on one shared track so opposite-direction trains never overlap, minimizing the total delay past each train's earliest departure.	Hard8	SortingDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Bovine AcrobaticsGiven weight groups with cow counts, build at most M towers where each cow's weight exceeds the cow above it by at least K, maximizing the cows used.	Hard8	SortingTwo pointers+1	No attempts yet	2s	1024 MB	Judgeable
Candy Cane FeastEach cane is fed to the cows in input order, and each cow eats the uneaten part up to her height, so the task is to print final heights after all canes.	Hard8	Segment treeGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Farmer John Actually FarmsFind the minimum day D so that each plant's height h_i + a_i*D has exactly t_i taller plants, or report -1 if no such day exists.	Hard8	Binary searchSorting+1	No attempts yet	2s	1024 MB	Judgeable
Taking PhotosPick a closed walk through a tree from room 1 that crosses each corridor twice, so each friend's interval covers both of their rooms; minimize the total interval length.	Hard8	TreeDynamic programming+2	No attempts yet	8s	1024 MB	Judgeable