Problems

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Total results29,085 problems

Entertainment with Javelins
Hard9
Dynamic programming, Sorting+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
DNA Decoding
Hard9
Trie, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Self-Driving Taxi
Hard9
Divide and conquer, Union-find+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Robogolf
Hard9
Dynamic programming, Sorting+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Packing Biscuits
Hard9
Bit manipulation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Oleg and Binary Sequences
Hard9
String matching, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sewing Graph
Hard9
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Seats
Hard9
Segment tree, Array+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Meetings
Hard9
Divide and conquer, Tree+1
No attempts yet
Time limit
4.5s
Memory limit
768 MB
Judgeable
Nowruz 1
Hard9
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nowruz 4
Hard9
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nowruz 8
Hard9
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Roller Coaster Railroad
Hard9
Sorting, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unscrambling a Messy Bug
Hard9
Bit manipulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pebbling odometer 4
Hard9
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Why the Cow Crossed Yonsei-ro
Hard9
Divide and conquer, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Vista 6
Hard9
Geometry, Sorting+2
No attempts yet
Time limit
0.1s
Memory limit
128 MB
Judgeable
Vista 8
Hard9
Geometry, Greedy+2
No attempts yet
Time limit
0.1s
Memory limit
128 MB
Judgeable
Vista 9
Hard9
Geometry, Greedy+2
No attempts yet
Time limit
0.1s
Memory limit
128 MB
Judgeable
Stock Analysis
Hard9
Prefix sum, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
814 - 3
Hard9
Geometry, Greedy+2
No attempts yet
Time limit
4.814s
Memory limit
814 MB
Judgeable
Homework
Hard9
Segment tree, Math+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Company Parties
Hard9
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Imperial Civilization
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Random Walk on a Tree: Expected Time
Hard9
Tree, Dynamic programming+2
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Minimum Spanning Tree of a Complete Graph
Hard9
Minimum spanning tree, Graph+2
No attempts yet
Time limit
5s
Memory limit
16 MB
Judgeable
Sail Shreds - 5
Hard9
Geometry, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sail Shreds - 9
Hard9
Geometry, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Meandian
Hard9
Sorting, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
MVP Diamond (Hard)
Hard9
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Addition Without Carries
Hard9
Greedy, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Data Placement
Hard9
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dart Game
Hard9
Dynamic programming, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Repairing the Bridges of Dungdung Island
Hard9
Tree, Greedy+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Regular Meeting 2
Hard9
Tree, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Cactus Shoppe
Hard9
Graph, DFS+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Pop music
Hard9
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Island
Hard9
Graph, Dynamic programming+1
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Even rain
Hard9
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Biggest Set Ever
Hard9
Combinatorics, Number theory
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Convex Sets on Graph
Hard9
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Justice For Everyone
Hard9
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Diamond Rush
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Dynamic Convex Hull
Hard9
Geometry, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
It's All Squares
Hard9
Geometry, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
King of Hot Pot
Hard9
Greedy, Sorting+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Fibonacci Partition
Hard9
Math, Number theory+1
No attempts yet
Time limit
10s
Memory limit
256 MB
Judgeable
Anti-hash Test
Hard9
String matching, Recursion+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Parity Sort
Hard9
Sorting, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cactus
Hard9
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Navy
Hard9
Divide and conquer, Union-find+1
No attempts yet
Time limit
25s
Memory limit
1024 MB
Judgeable
Stabbing Number
Hard9
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree Beauty
Hard9
Tree, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Find a Square
Hard9
Number theory, Math
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Geometrical Combinatorics
Hard9
Combinatorics, Geometry+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Evil Problemsetters
Hard9
Shortest path, Graph+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Game with stones
Hard9
Game theory, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hotels
Hard9
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Fibonacci Suffix Array
Hard9
String, Recursion+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Greatest Square
Hard9
Geometry, Segment tree+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Hamming Distance
Hard9
Divide and conquer, String matching+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Rikka with Maximum Subsegment Sum
Hard9
Divide and conquer, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Rikka with Storehouse
Hard9
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rikka with RCPC
Hard9
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rikka with Composite Number
Hard9
Math, Probability+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
House Building
Hard9
Greedy, Brute force+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Snow Wall
Hard9
Implementation, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bridge Building
Hard9
Tree, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Counting Good Arrays
Hard9
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Parity Constraint Perfect Matching
Hard9
Graph, Matrix+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Civilizations
Hard9
Geometry, Hash map+1
No attempts yet
Time limit
15s
Memory limit
512 MB
Judgeable
Instruction Anagram
Hard9
Combinatorics, Math+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
All Subsequences
Hard9
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cartesian MST
Hard9
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Game on a Tree
Hard9
Tree, Bit manipulation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Joyful Numbers
Hard9
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Minimal Cut
Hard9
Graph, Divide and conquer
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Longest Loose Segment
Hard9
Array, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Revenue
Hard9
Probability, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Assignment Problem
Hard9
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
Multiple?
Hard9
Combinatorics, Number theory+2
No attempts yet
Time limit
6s
Memory limit
256 MB
Judgeable
Excluded Min
Hard9
Array, Greedy+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
The Hash Table
Hard9
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Colorful Components
Hard9
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Belarusian State University
Hard9
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Brave Seekers of Unicorns
Hard9
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bytelandia States Union
Hard9
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Binary Supersonic Utahraptors
Hard9
Game theory, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Workers of the World Unite! Just Not Too Close.
Hard9
Dynamic programming, Greedy+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Painted Corridors
Hard9
Graph, BFS+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Derangement Rotations
Hard9
Combinatorics, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fantasmagorie
Hard9
Graph, Simulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
h-index
Hard9
Array, Segment tree+2
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
No Time to Dry
Hard9
Stack, Segment tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Counting Graphs
Hard9
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stone Game
Hard9
Game theory, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Go
Hard9
Divide and conquer, Union-find+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Games
Hard9
Game theory, Combinatorics+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Japanese Knowledge
Hard9
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Robot Vacuum 2
Hard9
Greedy, Simulation+2
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Entertainment with JavelinsChoose a minimum-cost subset of javelins, taken in the order the machine offers them, so that their throws break through all m layers of the target.	Hard9	Dynamic programmingSorting+1	No attempts yet	3s	512 MB	Judgeable
DNA DecodingAdd genes to a prefix-free set or append DNA strands, then report which strands become fully decodable for the first time after each operation.	Hard9	TrieString matching+1	No attempts yet	2s	512 MB	Judgeable
Self-Driving TaxiGiven hourly snow buildup and row or column plows, find the shortest taxi route under each trip's clearance limit, or report -1 if none exists.	Hard9	Divide and conquerUnion-find+1	No attempts yet	3s	512 MB	Judgeable
RobogolfTwo robots alternately move a chip right or down across an n by m grid with priced traps, and the task is to sum the game value over every starting square.	Hard9	Dynamic programmingSorting+1	No attempts yet	3s	512 MB	Judgeable
Packing BiscuitsGiven x bags and a[i] biscuits of tastiness 2^i, count the values y for which all x bags can each reach total tastiness exactly y.	Hard9	Bit manipulationGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Oleg and Binary SequencesCount binary sequences of length n whose Z-function matches the given entries, with -1 marking unknown values, modulo 1e9+7.	Hard9	String matchingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Sewing GraphFind the shortest alternating front/back sequence of edges that connects all N points on both sides with no crossings on either side.	Hard9	GeometrySorting+2	No attempts yet	2s	1024 MB	Judgeable
SeatsGiven an H by W grid of numbered contestants, count the rectangles holding exactly labels 0 to k-1, recomputed after each of Q swaps.	Hard9	Segment treeArray+1	No attempts yet	3s	512 MB	Judgeable
MeetingsGiven N mountain heights and Q intervals, find for each interval the meeting spot x that minimizes the total of max-heights from x to every person in the interval.	Hard9	Divide and conquerTree+1	No attempts yet	4.5s	768 MB	Judgeable
Nowruz 1Given a grid garden with rocks and k kids, plant bushes so the remaining free cells form a tree, maximizing the number of leaves (cells with exactly one free neighbor).	Hard9	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 4Given a grid with rocks, block more cells so the free cells form a tree, maximizing the number of free cells with exactly one free neighbor (output-only, partial scoring).	Hard9	TreeGreedy+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 8Given a grid with rocks and free cells, remove free cells so the remaining free cells form a tree (unique simple path between any two), maximizing the number of degree-one cells, an output-only task scored on the submitted maps.	Hard9	TreeGraph+2	No attempts yet	1s	512 MB	Judgeable
Roller Coaster RailroadOrder n railroad sections so each entry speed stays within its limit, then find the minimum total length of track placed between them.	Hard9	SortingDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Unscrambling a Messy BugFind a hidden bit permutation of n-bit integers (n a power of two) using at most w insertions and r membership queries after a single compile step.	Hard9	Bit manipulationImplementation+1	No attempts yet	2s	512 MB	Judgeable
Pebbling odometer 4Write a program in the odometer's own command language (move, turn, get/put, and label jumps) that gathers every pebble on the 256x256 grid into cell (0,0), using at most 200 commands.	Hard9	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Why the Cow Crossed Yonsei-roGiven two permutations of 1..N, sum over all cyclic rotations of each side the number of crossing pairs (inversions) between the two orders, modulo 1,000,000,009.	Hard9	Divide and conquerCombinatorics+2	No attempts yet	5s	1024 MB	Judgeable
Vista 6Given up to a million distinct points in the plane, output a cyclic order visiting all of them that is short enough under the Euclidean metric.	Hard9	GeometrySorting+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 8Given up to a million distinct points in the plane, output a cyclic tour that visits every point and returns to the start, under the Euclidean metric.	Hard9	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 9Given up to a million points in the plane, output a cyclic tour that visits each point once and returns to the start.	Hard9	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Stock AnalysisFor each of up to 200,000 queries (S, E, U), report the largest subarray sum within a[S..E] that does not exceed U, or NONE if none exists.	Hard9	Prefix sumSorting+2	No attempts yet	2s	512 MB	Judgeable
814 - 3Partition 8000 random points among 140 salesmen and give each a closed tour so the longest tour is as short as possible.	Hard9	GeometryGreedy+2	No attempts yet	4.814s	814 MB	Judgeable
HomeworkEach child builds an expression from range-assigned operators and integers; output the sum of all expression values modulo 1e9+7 under PEMDAS.	Hard9	Segment treeMath+2	No attempts yet	3s	1024 MB	Judgeable
Company PartiesGiven a rooted company tree with nondecreasing ages toward the root, answer M queries each asking which employees lie in the maximal connected subtree inside an age interval that contains the host.	Hard9	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Imperial CivilizationChoose a subset of stops that must include the first and last positions to maximize total resident satisfaction minus stop dissatisfaction, where each consecutive gap of length d scores the sum of \|d - d_i\|.	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	1.5s	512 MB	Judgeable
Random Walk on a Tree: Expected TimeGiven a tree, answer queries giving the expected hitting time of a random walk from one vertex to another, modulo 1e9+7.	Hard9	TreeDynamic programming+2	No attempts yet	2.5s	512 MB	Judgeable
Minimum Spanning Tree of a Complete GraphGiven a complete graph on N vertices where each edge weight is derived from vertex values by an arithmetic and XOR formula, find the total weight of the minimum spanning tree.	Hard9	Minimum spanning treeGraph+2	No attempts yet	5s	16 MB	Judgeable
Sail Shreds - 5Translate N triangles without rotating them so they tile an X by Y rectangle exactly, with no overlaps and nothing outside the sail.	Hard9	GeometryImplementation+1	No attempts yet	2s	512 MB	Judgeable
Sail Shreds - 9Place N triangles without rotating them so they tile an X by Y rectangle exactly, then print the new position of each triangle's vertex A.	Hard9	GeometryGreedy+1	No attempts yet	2s	512 MB	Judgeable
MeandianUsing at most 1000 queries to a library that returns the mean of the two middle salaries among any four distinct employees, recover every salary that is uniquely determined by the answers.	Hard9	SortingMath+2	No attempts yet	2s	512 MB	Judgeable
MVP Diamond (Hard)Given N monthly MVP tiers and four thresholds, find the maximum total spending that could produce that tier sequence, with each month capped at d and spend in units of 10,000.	Hard9	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
Addition Without CarriesGiven n binary numbers, choose b_i at least a_i so that no two b_i share a 1 bit, minimizing the sum, and print that sum in binary.	Hard9	GreedyBit manipulation	No attempts yet	2s	512 MB	Judgeable
Data PlacementGiven a connected undirected graph, find the minimum size of a vertex set A such that for every vertex outside A and every single removed edge, some vertex of A still reaches it, and count the minimum sets modulo 1e9+7.	Hard9	GraphDFS+1	No attempts yet	1s	512 MB	Judgeable
Dart GameGiven K rounds of weighted Seunggyu darts and movable Uiseok darts, compute the original score and the max and min achievable scores after relocating at most L Uiseok darts, all modulo 1e9+7.	Hard9	Dynamic programmingGeometry+2	No attempts yet	2s	512 MB	Judgeable
Repairing the Bridges of Dungdung IslandOn a tree where every edge costs 2, answer queries giving a capital u and a count a: choose a edges to make cost 1 so the sum of distances from all nodes to u is minimized.	Hard9	TreeGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Regular Meeting 2For each prefix of vertices 1 to i in a weighted tree, find the sum over X = 1 to K of the minimum possible maximum minimax-distance when placing X centers.	Hard9	TreeGreedy+1	No attempts yet	3s	1024 MB	Judgeable
Cactus ShoppeGiven a cactus whose vertices carry values, and divisibility queries, count the connected components left after deleting every vertex not divisible by the query.	Hard9	GraphDFS+2	No attempts yet	5s	1024 MB	Judgeable
Pop musicPick strictly increasing integers b_1 to b_n in the range 0 to m to maximize the sum of a_i times the number of ones in each b_i.	Hard9	Dynamic programmingBit manipulation+1	No attempts yet	5s	256 MB	Judgeable
IslandCount subsets of coastal settlements such that every lake-boundary settlement can reach a chosen one through a planar road network, modulo 10^9+7.	Hard9	GraphDynamic programming+1	No attempts yet	7s	512 MB	Judgeable
Even rainCount the ways to zero out k of n columns so that the trapped rain area is even, modulo 10^9+7, with n up to 25,000 and k up to 25.	Hard9	Dynamic programmingPrefix sum+1	No attempts yet	3s	512 MB	Judgeable
Biggest Set EverCount subsets of {0, ..., T-1} whose element sum is congruent to rem modulo n, for a huge T, modulo 998244353.	Hard9	CombinatoricsNumber theory	No attempts yet	3s	512 MB	Judgeable
Convex Sets on GraphCount the vertex subsets S of a connected graph where every simple path between two vertices of S lies entirely inside S, modulo 998244353.	Hard9	GraphDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Justice For EveryoneCount the orders of pair increments that turn distinct starting numbers a into distinct targets b, keeping all numbers distinct at every step, modulo 998244353.	Hard9	CombinatoricsDynamic programming+1	No attempts yet	10s	512 MB	Judgeable
Diamond RushGiven an n by n grid of weights, answer queries asking for the maximum path sum from (1,1) to (n,n) of powers of n^2 while avoiding a blocked rectangle.	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	4s	512 MB	Judgeable
Dynamic Convex HullMaintain a set of functions (x-a)^4+b under insertions and deletions, and report the minimum value at each queried point x.	Hard9	GeometrySegment tree+1	No attempts yet	4s	512 MB	Judgeable
It's All SquaresGiven a grid of cell values and a closed simple route for each query, count the distinct values of the cells enclosed by that route.	Hard9	GeometrySegment tree+1	No attempts yet	4s	512 MB	Judgeable
King of Hot PotGiven n dishes with ready times a_i and eating times b_i, find for each k the minimum total time to fully eat k chosen dishes one at a time.	Hard9	GreedySorting+1	No attempts yet	4s	512 MB	Judgeable
Fibonacci PartitionAfter each update X += a_i * F_{b_i}, the task asks for partition(X), the largest number of distinct Fibonacci numbers that sum to X.	Hard9	MathNumber theory+1	No attempts yet	10s	256 MB	Judgeable
Anti-hash TestCount occurrences of u in the popcount-parity string s(n) of length 2^n, and how many strings v share that occurrence count.	Hard9	String matchingRecursion+1	No attempts yet	1s	256 MB	Judgeable
Parity SortSort a permutation of 0 to n-1 in at most 30 operations, where each operation splits the selected positions into even and odd values and reorders them.	Hard9	SortingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
CactusGiven a cactus graph with XOR edge costs, answer each query with the k-th smallest distinct XOR value over all simple paths between two vertices.	Hard9	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
NavyFor each night t, count the rivers whose removal splits the graph, where the rivers are the union of the sets A for weather B_t and B_(t+1).	Hard9	Divide and conquerUnion-find+1	No attempts yet	25s	1024 MB	Judgeable
Stabbing NumberGiven a histogram polygon drawn in ASCII, find a rectangle decomposition that minimizes the maximum number of rectangles an axis-parallel segment crosses.	Hard9	Dynamic programmingBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Tree BeautyGiven a rooted tree, apply updates that add floor(Y/K^depth) to a subtree and answer subtree sum queries. N and Q are up to 100,000.	Hard9	TreeSegment tree+2	No attempts yet	2s	512 MB	Judgeable
Find a SquareGiven p(x) = a·x^2 + b·x + c, find the largest square dividing the product of p(0) through p(n-1), modulo 10^9+7.	Hard9	Number theoryMath	No attempts yet	6s	512 MB	Judgeable
Geometrical CombinatoricsGiven three integer vertices of a triangle, sum the Pascal's triangle values at lattice points inside or on it, modulo 10^9+7, for up to 5 tests.	Hard9	CombinatoricsGeometry+1	No attempts yet	3s	512 MB	Judgeable
Evil ProblemsettersGiven a grid with up to 42 black holes, find the shortest path from the entrance to the exit for each query, or -1 if it is unreachable.	Hard9	Shortest pathGraph+1	No attempts yet	10s	1024 MB	Judgeable
Game with stonesCount the ways to color each of n piles black or white so that Bob wins the Steins;Game under optimal play, modulo 1000000007.	Hard9	Game theoryBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
HotelsGiven a weighted tree and three independent uniform choices of vertices from three candidate sets, find the expected total distance from the three chosen vertices to their median (the vertex minimizing the sum of distances).	Hard9	TreeDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
Fibonacci Suffix ArrayGiven n, q, and m, the task finds the suffix array of the Fibonacci word fib_n at q query positions and prints each value modulo m.	Hard9	StringRecursion+1	No attempts yet	5s	512 MB	Judgeable
Greatest SquareGiven a rectilinear simple polygon and query points, find the largest axis-parallel square inside it with each point as its lower left corner.	Hard9	GeometrySegment tree+1	No attempts yet	8s	512 MB	Judgeable
Hamming DistanceGiven a sequence a of length n and m, find the minimum and the sum mod 1e9+7 of Hamming distances to every length-n window of S^m.	Hard9	Divide and conquerString matching+1	No attempts yet	3s	512 MB	Judgeable
Rikka with Maximum Subsegment SumGiven an integer array of length up to 1e5, sum the maximum subsegment sum over every subsegment and output the result modulo 2^64.	Hard9	Divide and conquerPrefix sum+1	No attempts yet	3s	512 MB	Judgeable
Rikka with StorehouseOn a complete binary tree of 2^n-1 nodes, the last half of node values are given and updated; minimize the sum of squared edge differences over the free nodes after each update, modulo 998244353.	Hard9	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Rikka with RCPCPick the days to answer questions so the total attack is minimized, where a free answer needs K consecutive ignored days before it.	Hard9	Dynamic programmingPrefix sum+1	No attempts yet	1s	512 MB	Judgeable
Rikka with Composite NumberGiven a set of digits, find the expected number of random digits drawn before the growing decimal number first becomes composite, modulo 998244353.	Hard9	MathProbability+2	No attempts yet	1s	512 MB	Judgeable
House BuildingPlace K houses on an N by M grid so that the total happiness, each house's value times its Manhattan distance to the nearest other house, is as large as possible.	Hard9	GreedyBrute force+2	No attempts yet	4s	1024 MB	Judgeable
Snow WallStack blocks of given widths into a wall of width W as tall as possible, with no two consecutive rows sharing a gap position and every block endpoint supported below.	Hard9	ImplementationGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Bridge BuildingGiven a weighted tree and up to two extra edges, answer queries for the shortest path between pairs of vertices after adding those edges.	Hard9	TreeShortest path+2	No attempts yet	2s	1024 MB	Judgeable
Counting Good ArraysCount permutations of 1..n with one value duplicated, whose inversion-like score falls in [a,b], modulo 1e9+7.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Parity Constraint Perfect MatchingGiven a weighted bipartite graph, find one perfect matching with an even weight sum and one with an odd weight sum, or print -1 when none exists.	Hard9	GraphMatrix+1	No attempts yet	1s	1024 MB	Judgeable
CivilizationsAfter each ownership change, report the largest power Aw+Bl+Cwl among civilizations that own at least one field, where w is wealth and l is border length.	Hard9	GeometryHash map+1	No attempts yet	15s	512 MB	Judgeable
Instruction AnagramCount strings S consistent with observations, given that P is an anagram of S and the robot's positions at certain times are known.	Hard9	CombinatoricsMath+2	No attempts yet	4s	512 MB	Judgeable
All SubsequencesSum the absolute product of consecutive differences over every subsequence of A, modulo 998244353.	Hard9	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
Cartesian MSTGiven two connected weighted graphs G and H, compute the total weight of the minimum spanning tree of their Cartesian product G square H.	Hard9	GraphMinimum spanning tree+2	No attempts yet	1s	512 MB	Judgeable
Game on a TreeFriends draw colored cards along tree paths, score each deck by GCD, then replace one card per round. Output each friend's points modulo 1e9+7.	Hard9	TreeBit manipulation+2	No attempts yet	5s	512 MB	Judgeable
Joyful NumbersA number n is joyful when appending 25 to its digits gives a square; for the k-th joyful number, report how many distinct primes divide it.	Hard9	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Minimal CutGiven a weighted undirected graph plus a cycle of 10^9-weight edges through all vertices, sum the minimum cut values over all vertex pairs modulo 998244353.	Hard9	GraphDivide and conquer	No attempts yet	3s	1024 MB	Judgeable
Longest Loose SegmentGiven an array that changes through swaps over up to 30 turns, find the longest segment whose max plus min exceeds its length, for the initial array and after each turn.	Hard9	ArraySegment tree+1	No attempts yet	2s	256 MB	Judgeable
RevenueGiven item prices and each item's value distribution, find the lowest expected revenue over all joint distributions of buyer values that share those marginals.	Hard9	ProbabilitySorting+1	No attempts yet	1s	256 MB	Judgeable
Assignment ProblemGiven each position's full ranking of n candidates, list every candidate that some consistent profit matrix makes part of the unique optimal assignment.	Hard9	Dynamic programmingBit manipulation+1	No attempts yet	4s	256 MB	Judgeable
Multiple?Count sequences of length n-k with entries in [1,n] such that no non-empty subsequence sums to a multiple of n, modulo 998244353.	Hard9	CombinatoricsNumber theory+2	No attempts yet	6s	256 MB	Judgeable
Excluded MinFor each query range of the array, find the maximum mex reachable by repeatedly moving one copy of a duplicated value to an adjacent value.	Hard9	ArrayGreedy+1	No attempts yet	10s	512 MB	Judgeable
The Hash TableGiven n and m, find the total insertion cost when elements 0 to n-1 go into m slots at i^2 mod m, where each insert costs the slot's current size.	Hard9	Number theoryMath+1	No attempts yet	1s	512 MB	Judgeable
Colorful ComponentsCount labeled trees on n colored vertices such that the monochromatic components left after deleting bichromatic edges each have size at most k, modulo 1e9+7.	Hard9	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Belarusian State UniversityGiven a lookup table c(i, x_i, y_i) for each bit, count how often each value of f(a, b) appears over all pairs a in A and b in B, with n up to 18.	Hard9	Bit manipulationMath+1	No attempts yet	2s	512 MB	Judgeable
Brave Seekers of UnicornsCount strictly increasing sequences of distinct integers from 1 to n with no three consecutive elements XORing to zero, modulo 998244353.	Hard9	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Bytelandia States UnionFind the minimum total time to walk from a start square to a portal on a huge grid with position-dependent move costs, modulo 998244353.	Hard9	MathImplementation	No attempts yet	2s	512 MB	Judgeable
Binary Supersonic UtahraptorsAlexey and Boris repeatedly exchange fixed-size groups of yellow or red utahraptors; find the game value \|a_y - b_r\| under optimal play.	Hard9	Game theoryGreedy+2	No attempts yet	1s	512 MB	Judgeable
Workers of the World Unite! Just Not Too Close.Assign n workers to n gates (each gate used once, corridor A or B) and to n workstations, respecting the A-north/B-south adjacency restriction, to minimize total travel distance.	Hard9	Dynamic programmingGreedy+2	No attempts yet	10s	1024 MB	Judgeable
Painted CorridorsDecide whether three robots starting at given junctions can paint every colored corridor, with secondary colors needing two robots to traverse together.	Hard9	GraphBFS+1	No attempts yet	5s	512 MB	Judgeable
Derangement RotationsCount derangements of size n whose set of derangement rotations has exactly n-2 distinct rotations, modulo a prime p.	Hard9	CombinatoricsMath+2	No attempts yet	1s	512 MB	Judgeable
FantasmagorieFind a sequence of single-pixel flips that turns the first black and white image into the second while keeping each color's region count fixed.	Hard9	GraphSimulation+1	No attempts yet	1s	512 MB	Judgeable
h-indexFor each of q range queries on an array of citation counts, find the largest h such that the range contains at least h values greater than or equal to h.	Hard9	ArraySegment tree+2	No attempts yet	2.5s	512 MB	Judgeable
No Time to DryGiven a color array and Q ranges, find the minimum brush strokes to paint each range where lighter colors can be overpainted by darker ones.	Hard9	StackSegment tree+2	No attempts yet	1s	512 MB	Judgeable
Counting GraphsGiven a connected undirected graph, count the graphs whose walk lengths from vertex 1 to every vertex match the original, modulo 1000000007.	Hard9	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Stone GameCount the opening moves (pile and stone count) that let Bessie force a win in a game where each removed amount must be a multiple of the previous one.	Hard9	Game theoryNumber theory+2	No attempts yet	1s	512 MB	Judgeable
GoGiven an n by n Go board, flip each stone in turn and count the white stones with no liberties, then output the base-hashed sequence of those counts modulo 1000000007.	Hard9	Divide and conquerUnion-find+2	No attempts yet	6s	512 MB	Judgeable
GamesCount the distinguishable piles of K stones drawn from the N given sizes where the first player loses in a Nim variant that removes from at most 6 piles.	Hard9	Game theoryCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
Japanese KnowledgeFor each k from 0 to N, count non-decreasing sequences x with x_i at most A_i in which exactly k positions have x_i equal to A_i, modulo 998244353.	Hard9	Dynamic programmingDivide and conquer+2	No attempts yet	10s	512 MB	Judgeable
Robot Vacuum 2Given a grid warehouse with boxes and a start cell, output a command string of length N that maximizes the number of distinct cells the vacuum visits.	Hard9	GreedySimulation+2	No attempts yet	12s	1024 MB	Judgeable