Problems

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Total results29,068 problems

Game with a tree
Hard9
Trie, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Random Tree
Hard9
Tree, Probability+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Walk Through Brooklyn
Hard9
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Card Game
Hard9
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Max and Duke
Hard9
String, String matching+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
In Search of the Unknown
Hard9
Graph, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fraction paradox
Hard9
Geometry, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Maps
Hard9
Segment tree, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candelabra
Hard9
Divide and conquer, Tree+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Very Strange String
Hard9
String matching, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
SAVE the World (Small)
Hard9
Greedy, Simulation+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
SAVE the World (Large)
Hard9
Greedy, Sorting+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Kevin's Player
Hard9
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Triangular Number of a Polygon
Hard9
Math, Number theory+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Evacuation
Hard9
Tree, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Jenga
Hard9
Game theory, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Two Captains
Hard9
Dynamic programming, Simulation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Fibonacci Digit Count
Hard9
Math, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Machine Learning
Hard9
Backtracking, Trie+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Light Inconvenience
Hard9
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Truck Driver
Hard9
Tree, Dynamic programming+1
No attempts yet
Time limit
4.5s
Memory limit
1024 MB
Judgeable
Lockpicking
Hard9
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Closing Time
Hard9
Tree, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Soccer Stadium
Hard9
Matrix, Dynamic programming+1
No attempts yet
Time limit
3.5s
Memory limit
1024 MB
Judgeable
Beech Tree
Hard9
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Overtaking
Hard9
Segment tree, Binary search+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Robot Contest
Hard9
Simulation, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mineral Collection
Hard9
Sorting, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Ties That Guide Us
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Segment Union
Hard9
Sorting, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Magical BF 4
Hard9
Implementation, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Sequences
Hard9
String, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Arc of Triumph 1
Hard9
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
N-Queen (Special)
Hard9
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
HLD
Hard9
Tree, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Gemini Tree (Ver.Jadeite)
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Best parentheses
Hard9
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Queue
Hard9
Linked list, String matching+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Magic
Hard9
Geometry, Divide and conquer+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Count
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
6s
Memory limit
2048 MB
Judgeable
Butterfly and Telephone Poles (Hard)
Hard9
Dynamic programming, Segment tree+1
No attempts yet
Time limit
4.5s
Memory limit
1024 MB
Judgeable
Osmanthus Tree
Hard9
Dynamic programming, Tree+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Why Hobanwoo was late for school 7
Hard9
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Why Hobanwoo Was Late for School 8
Hard9
Dynamic programming, Geometry+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mike Sees The Storm (Large)
Hard9
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Impartial Strings
Hard9
String matching, Math
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Binary Trees
Hard9
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Gasoline Prices
Hard9
Tree, Union-find+1
No attempts yet
Time limit
3.5s
Memory limit
1024 MB
Judgeable
Assigning Fares
Hard9
Tree, Union-find+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Double Palindrome
Hard9
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cartesian
Hard9
Binary search, Dynamic programming+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Substring in a Substring
Hard9
String matching, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Monkey and Bananas
Hard9
Geometry, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Unfreezing the Scoreboard
Hard9
Sorting, Prefix sum+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Curfew
Hard9
Binary search, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Programmable Snake
Hard9
Math, Number theory+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Igor and the Toys
Hard9
Geometry, Divide and conquer+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Apricot Seeds
Hard9
Sorting, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
2048 MB
Judgeable
M. S. I. S.
Hard9
Dynamic programming, Graph+1
No attempts yet
Time limit
0.5s
Memory limit
2048 MB
Judgeable
Bus Driver Gathering Sets
Hard9
Segment tree, Bit manipulation+1
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Organizing Bags in Mabinogi
Hard9
Segment tree, Divide and conquer+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Vault Heist 2
Hard9
Tree, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Patrol Duty
Hard9
Graph, Implementation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Multiplayer Game
Hard9
Array, Math+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Tube Master III
Hard9
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Popcount Words
Hard9
String matching, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Wiring Engineering
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
LIS Counting
Hard9
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gebyte's Grind
Hard9
Segment tree, Greedy+1
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Paimon Segment Tree
Hard9
Segment tree, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Paimon Polygon
Hard9
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Paimon's Tree
Hard9
Dynamic programming, Tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Crystalfly
Hard9
Dynamic programming, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cloud Retainer's Game
Hard9
Dynamic programming, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Octopus's Garden
Hard9
Graph, DFS+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Tree Embedding
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Biology
Hard9
Geometry, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Land Sale
Hard9
Math, Number theory+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Sequence and Mischief
Hard9
Segment tree, Implementation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Sorted Fractal Sequence
Hard9
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Matrix Fraud
Hard9
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
1D Stone Game 1
Hard9
Game theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Minimum Spanning Tree Redrawing Game
Hard9
Minimum spanning tree, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Good Luck in Your Service, Haneul
Hard9
Math, Combinatorics+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Island
Hard9
Graph, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
On the Grid
Hard9
Matrix, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bit Counting Sequence
Hard9
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Highway Tolls
Hard9
Graph, Shortest path+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Marathon Race 2
Hard9
Greedy, Prefix sum+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Lepeze
Hard9
Combinatorics, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Robots
Hard9
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sandpile on Clique
Hard9
Math, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Permutation Group
Hard9
Combinatorics, Math
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Interleaving Sequences
Hard9
Array, Two pointers+1
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Desant 3
Hard9
Bit manipulation, Combinatorics+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Colorful Forest
Hard9
Tree, Graph+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Ladybug
Hard9
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Schedule
Hard9
Combinatorics, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Recurring Problem
Hard9
Math, Binary search+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Meow
Hard9
Tree, Dynamic programming+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Game with a treeAfter each action, count the distinct substrings of all root-to-apple words, where apples are added with letters and removed when picked.	Hard9	TrieTree+1	No attempts yet	2s	1024 MB	Judgeable
Random TreeFor each prefix of a randomly grown tree, print the sum over all vertex subsets A of the number of vertices in the minimal subtree connecting A, modulo 998244353.	Hard9	TreeProbability+1	No attempts yet	2s	1024 MB	Judgeable
A Walk Through BrooklynPick a walk from the north edge to the south edge along house boundaries that splits the grid area into two parts with the smallest difference.	Hard9	GraphDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Card GameSplit a shuffled deck of n cards, k of them face down, into two piles with equal face-down counts using Reverse, Move, and Up actions.	Hard9	MathImplementation+1	No attempts yet	2s	1024 MB	Judgeable
Max and DukeGiven a string s and m queries [l, r], count the palindromic substrings that lie entirely inside s[l..r] for each query.	Hard9	StringString matching+2	No attempts yet	4s	1024 MB	Judgeable
In Search of the UnknownCount the routes that visit every house exactly once in an undirected street graph with up to 1000 houses, and print the count modulo 2.	Hard9	GraphCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Fraction paradoxGiven k irreducible fractions, pick four distinct ones forming two pairs with a at most b and c at most d, maximizing (a+c)/(b+d) minus (...) of the other pair.	Hard9	GeometryGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Two MapsAfter each insert or delete of a segment, count the pairs of current segments whose union length equals s.	Hard9	Segment treeDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
CandelabraGiven a tree of n vertices labeled with letters a to t, find the longest path subsequence with no palindromic substring of length 2 or more.	Hard9	Divide and conquerTree+2	No attempts yet	5s	1024 MB	Judgeable
Very Strange StringGiven k and m, the task is to build a lowercase string of length at most m whose strangeness (the sum of G_i times F_i) equals k.	Hard9	String matchingMath+1	No attempts yet	2s	1024 MB	Judgeable
SAVE the World (Small)Output a move string for each hero on the grid so all of them reach (0,0) without revisiting a cell, colliding, or arriving together.	Hard9	GreedySimulation+1	No attempts yet	5s	1024 MB	Judgeable
SAVE the World (Large)Give each hero a move string so all heroes reach (0,0) without collisions or revisits, keeping the longest string close to the sorted Chebyshev distance bound.	Hard9	GreedySorting+1	No attempts yet	5s	1024 MB	Judgeable
Kevin's PlayerGiven songs with joy-valued liked segments and a speed-up factor v, find the minimum listening time needed to gather joy F.	Hard9	Dynamic programmingGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Triangular Number of a PolygonGiven a regular n-gon with vertices colored W or B, print the count of same-colored isosceles triangles after each of m single-vertex color flips.	Hard9	MathNumber theory+1	No attempts yet	3s	1024 MB	Judgeable
EvacuationEach room has one person who must reach a leaf exit before the detonator on each corridor fires. Find the maximum number who escape.	Hard9	TreeDynamic programming+2	No attempts yet	3s	1024 MB	Judgeable
JengaTwo players take turns moving blocks in a Jenga tower, and whoever leaves an unstable layer below the top one loses. The task asks who wins with optimal play.	Hard9	Game theoryDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Two CaptainsGiven two command plans over n cannons, find the fewest rum commands to insert so no cannon ever holds crew from both captains.	Hard9	Dynamic programmingSimulation+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
Machine LearningGiven every binary word up to length n marked accept or reject, build a DFA with the fewest states that matches all the marks.	Hard9	BacktrackingTrie+1	No attempts yet	2s	1024 MB	Judgeable
A Light InconveniencePerformers join or leave a line over Q acts, and you must pick a fire-spread value t_a up to 5p_a while keeping the lit torches at 150 or fewer.	Hard9	MathImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Truck DriverGiven a weighted tree with delivery counts per city that change over Q updates, find the maximum round-trip delivery time from city 0 after each update.	Hard9	TreeDynamic programming+1	No attempts yet	4.5s	1024 MB	Judgeable
LockpickingBuild a keycard that keeps the error count below N from every unknown starting state of the lock, for up to 10^7 rounds.	Hard9	GraphDFS+1	No attempts yet	1s	1024 MB	Judgeable
Closing TimeGiven a weighted tree and cities X and Y, pick nonnegative closing times with sum at most K to maximize reachable cities from X plus from Y.	Hard9	TreeBinary search+1	No attempts yet	1s	1024 MB	Judgeable
Soccer StadiumGiven an N by N grid with trees, find the largest set of empty cells where any two cells connect within two straight row or column moves inside the set.	Hard9	MatrixDynamic programming+1	No attempts yet	3.5s	1024 MB	Judgeable
Beech TreeFor each node r, decide whether its subtree has a beautiful permutation, where each node's parent is fixed by how often its edge color appeared before.	Hard9	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
OvertakingBuses on a one-way road can overtake only at sorting stations. For each query departure time Y of a reserve bus, find when it reaches the hotel.	Hard9	Segment treeBinary search+2	No attempts yet	2s	1024 MB	Judgeable
Robot ContestWrite a Pulibot program that colors one shortest path from (0,0) to (H-1,W-1) with 1 and every other empty cell with 0 in an unknown maze.	Hard9	SimulationBFS+1	No attempts yet	1s	1024 MB	Judgeable
Mineral CollectionGiven minerals on a ray from position 0, answer for each query whether two named minerals can share one gem in a minimum-energy collection plan.	Hard9	SortingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
The Ties That Guide UsAssign tie counts to the rooms of a tree with at most 3 doors per room so you can reach the safe room within d+30 door passes from any start.	Hard9	TreeDivide and conquer+1	No attempts yet	5s	1024 MB	Judgeable
Segment UnionGiven centers x_i and radii a_i, sum the union length of the intervals [x_i - r, x_i + r] over all ways to assign the radii to the centers, modulo 1e9+7.	Hard9	SortingDynamic programming+1	No attempts yet	5s	1024 MB	Judgeable
Magical BF 4Write an N by N grid of BF code that computes F_k into cell M0 whether the grid is read by rows or by columns, for k from 3 to 10.	Hard9	ImplementationSimulation+1	No attempts yet	1s	1024 MB	Judgeable
Two SequencesFor each query, find the k-th element of the lexicographically smallest merge of the prefixes A[1..a] and B[1..b].	Hard9	StringGreedy+1	No attempts yet	3s	1024 MB	Judgeable
Arc of Triumph 1Find a stable construction order for an arch cross-section using the fewest wooden scaffold blocks, and output every placement and removal step.	Hard9	ImplementationSimulation+2	No attempts yet	1s	1024 MB	Judgeable
N-Queen (Special)Given an N x N board with Q queens already fixed, place the remaining queens so that no two attack each other, or print -1 if that is impossible.	Hard9	MathImplementation	No attempts yet	1s	512 MB	Judgeable
HLDAfter each update adds k copies of a tree path, print the fewest light edges achievable when each vertex keeps at most one heavy child edge.	Hard9	TreeDynamic programming+1	No attempts yet	5s	1024 MB	Judgeable
Gemini Tree (Ver.Jadeite)Given a weighted tree with green and blue stones, find the minimum swap cost to split it into single-color parts after each edge length update.	Hard9	TreeDivide and conquer+1	No attempts yet	5s	1024 MB	Judgeable
Best parenthesesChoose a subsequence of parentheses that forms a balanced string, maximizing the sum of the chosen c values.	Hard9	Dynamic programmingDivide and conquer+2	No attempts yet	2s	1024 MB	Judgeable
QueueWorms with lengths 1 to 6 are merged and split in queues, and the task asks for the product of f(t) over all length-k substrings of s.	Hard9	Linked listString matching+1	No attempts yet	1s	2048 MB	Judgeable
MagicEach round deletes some points (indices decoded from the previous answer). Print twice the convex hull area of the remaining points each round.	Hard9	GeometryDivide and conquer+1	No attempts yet	3s	1024 MB	Judgeable
CountGiven a rooted tree and queries (u, d), build the edge set induced by vertices within distance d of u using at most M calls to R and C.	Hard9	TreeDivide and conquer+1	No attempts yet	6s	2048 MB	Judgeable
Butterfly and Telephone Poles (Hard)Pole heights change over time. For each query at start pole p, find the valid wire chain with the largest total length and print its squared cost.	Hard9	Dynamic programmingSegment tree+1	No attempts yet	4.5s	1024 MB	Judgeable
Osmanthus TreeCount trees on n+m vertices that keep the LCAs of the given tree T on vertices 1 to n and keep each pairwise LCA label within max(i, j) + k, modulo 1e9+7.	Hard9	Dynamic programmingTree+1	No attempts yet	0.5s	1024 MB	Judgeable
Why Hobanwoo was late for school 7For each root, find how much sungsu must be poured until node M is full, when each pour goes equally to the smallest and largest unfilled child.	Hard9	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
Why Hobanwoo Was Late for School 8Find the minimum total time to reach planet N from the origin, where a move to planet e costs a_e if the start lies on the hull of planets 0 to e, otherwise b_e.	Hard9	Dynamic programmingGeometry+1	No attempts yet	2s	1024 MB	Judgeable
Mike Sees The Storm (Large)Sum the K-th power of the maximum prefix value over all balanced +1/-1 walks of length 2N from 0, modulo 1e9+7.	Hard9	MathCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
Impartial StringsFor each case, decide whether a finite automaton can generate exactly the strings where S and T occur equally often as substrings.	Hard9	String matchingMath	No attempts yet	4s	1024 MB	Judgeable
Binary TreesGiven two rooted binary trees on N vertices, output at most N subtree-move operations that turn the first tree into one isomorphic to the second.	Hard9	TreeGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Gasoline PricesGiven a tree with a price range per station, count valid price assignments after each year's pair of path constraints forces matching prices along both paths.	Hard9	TreeUnion-find+1	No attempts yet	3.5s	1024 MB	Judgeable
Assigning FaresGiven a tree of n stations and m metro paths, orient each path and assign fare zones that strictly increase along every path, minimizing the largest zone.	Hard9	TreeUnion-find+2	No attempts yet	6s	1024 MB	Judgeable
Double PalindromeCounts substrings of s that split into two equal-length halves, where each half is a palindrome, with n up to 500000.	Hard9	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
CartesianGiven n points, pick k disjoint pairs so the common intersection of their bounding rectangles is a square; find the largest possible side length.	Hard9	Binary searchDynamic programming+1	No attempts yet	10s	1024 MB	Judgeable
Substring in a SubstringFor each query, count how many times the substring s[l1..r1] occurs inside the substring t[l2..r2] of two given strings.	Hard9	String matchingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Monkey and BananasGiven n rotating triangles with a marked winning vertex each, find the largest number of winning vertices that can be lowest at the same rotation angle.	Hard9	GeometrySorting+1	No attempts yet	3s	1024 MB	Judgeable
Unfreezing the ScoreboardGiven a preliminary scoreboard and announced scores, find a student's best and worst possible final place when offline-checked points are awarded only after full regular-test marks.	Hard9	SortingPrefix sum+2	No attempts yet	4s	1024 MB	Judgeable
CurfewStudents move up to d rooms or hide before instructors count each room, minimizing the worse of the two instructors' counts of rooms that do not hold b students.	Hard9	Binary searchPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Programmable SnakeFind the longest snake that can be placed on an H by W torus and keep moving forever under a repeating K-command program without hitting itself.	Hard9	MathNumber theory+1	No attempts yet	3s	1024 MB	Judgeable
Igor and the ToysGiven N convex polygons resting on the x-axis, answer Q queries: for two toys, find the minimum width of the box after pushing them together side by side in either order.	Hard9	GeometryDivide and conquer+1	No attempts yet	2.5s	1024 MB	Judgeable
Apricot SeedsFor many queries, find the sum of positions l to r after m bubble sort passes applied to the seeds from position s to e.	Hard9	SortingSegment tree+1	No attempts yet	3s	2048 MB	Judgeable
M. S. I. S.Given a 2 by n matrix, reorder its columns to maximize the sum of the best increasing subsequence sums in the two rows.	Hard9	Dynamic programmingGraph+1	No attempts yet	0.5s	2048 MB	Judgeable
Bus Driver Gathering SetsGiven N sets of driver skills (0 to 50), process range updates, swaps, and queries that print skills of the excellent or poor driver sets in an interval.	Hard9	Segment treeBit manipulation+1	No attempts yet	6s	512 MB	Judgeable
Organizing Bags in MabinogiAfter each record, find the maximum total value of non-overlapping items (sizes 1x1 to 2x2, no rotation) that fit in the current bag.	Hard9	Segment treeDivide and conquer+1	No attempts yet	4s	1024 MB	Judgeable
Vault Heist 2Jeonghu builds a tree of at most 100 vertices, each with at most 3 edges, that encodes a number up to 10^18 so Yeongu can recover it after one edge is cut.	Hard9	TreeMath+1	No attempts yet	2s	1024 MB	Judgeable
Patrol DutyFind a walk on a hexagonal grid of cells that visits every cell exactly once in each period of K steps, starting from a given cell.	Hard9	GraphImplementation+1	No attempts yet	3s	1024 MB	Judgeable
Multiplayer GameBrue submits a permutation of length N so that Mingyu can recover a bit string of length L from its pivot-partitioned shuffle.	Hard9	ArrayMath+1	No attempts yet	3s	1024 MB	Judgeable
Tube Master IIIChoose tubes on an n by m grid so each cell touches exactly count turning points, at minimum total tube cost, or report -1 if impossible.	Hard9	GraphShortest path+1	No attempts yet	1s	1024 MB	Judgeable
Popcount WordsEach interval contributes the parity of popcount over its range, the parts are concatenated, and each query counts how often its 0/1 pattern appears in the result.	Hard9	String matchingBit manipulation+1	No attempts yet	1s	1024 MB	Judgeable
Wiring EngineeringGiven a weight matrix and building and tower install costs, answer many range queries for the maximum profit of non-crossing wires within chosen index ranges.	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	8s	1024 MB	Judgeable
LIS CountingGiven N, M, and a prime P, count permutations of length N*M with LIS N and LDS M, broken down by the value at each position, modulo P.	Hard9	Dynamic programmingCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Gebyte's GrindWith point updates to a trail of beasts, inns, and witches, find the farthest object reachable from a given start with fixed starting health.	Hard9	Segment treeGreedy+1	No attempts yet	12s	1024 MB	Judgeable
Paimon Segment TreeGiven an array changed by m range additions, answer q queries for the sum of squared values over an index range and a version range, modulo 1e9+7.	Hard9	Segment treePrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Paimon PolygonSplit the points besides O into two groups, each forming a strict convex polygon with O whose edges meet only at O, and maximize the total perimeter.	Hard9	GeometrySorting+1	No attempts yet	2s	1024 MB	Judgeable
Paimon's TreeChoose a starting vertex and a growth order so the i-th added edge gets weight a_i, then maximize the diameter of the resulting weighted tree.	Hard9	Dynamic programmingTree+1	No attempts yet	4s	1024 MB	Judgeable
CrystalflyGiven a tree where each vertex has flies and a 1 to 3 second disappearance timer, find the most flies Paimon can catch starting from vertex 1.	Hard9	Dynamic programmingTree+1	No attempts yet	2s	1024 MB	Judgeable
Cloud Retainer's GameRemove some wooden boards so a pinball bouncing between y=0 and y=H collects as many coins as possible, and report the maximum count.	Hard9	Dynamic programmingSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Octopus's GardenGiven a triangulated convex polygon with interior points, list all triangles so that every prefix forms a simply connected set of triangles, starting from a given triangle.	Hard9	GraphDFS+2	No attempts yet	5s	1024 MB	Judgeable
Tree EmbeddingGiven a weighted tree, assign each vertex a vector of at most 16 integers so the max coordinate gap between two vectors equals their tree distance.	Hard9	TreeDivide and conquer+1	No attempts yet	1s	1024 MB	Judgeable
BiologyConstruct 16 points and a planar straight-line graph on them with more than 300000 simple polygons formed by its edges.	Hard9	GeometryGraph+1	No attempts yet	1s	1024 MB	Judgeable
Land SaleEach grid cell is (pi+q) added to (rj+s) without carry in base B, and each query asks for the carry-free sum of all cells in its rectangle, written in base B.	Hard9	MathNumber theory+1	No attempts yet	5s	1024 MB	Judgeable
Sequence and MischiefProcess deletions, range subtract-min and add-max updates on a sequence, and answer third-distinct-maximum queries on subarrays.	Hard9	Segment treeImplementation+1	No attempts yet	3s	1024 MB	Judgeable
Sorted Fractal SequenceCount non-decreasing sequences of length N where a[a[i]] equals a[i] for every i, with K fixed entries, modulo M.	Hard9	Dynamic programmingCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
Matrix FraudFind the fewest cell toggles that make every row a contiguous block of 1s, every column contain a 1, and both row endpoints never move left.	Hard9	Dynamic programmingPrefix sum+1	No attempts yet	1s	2048 MB	Judgeable
1D Stone Game 1Given n stones in a row, two players alternately take runs of stones whose length is one more than the opponent's last take, with discarding rules; output who wins for each n.	Hard9	Game theoryMath	No attempts yet	1s	1024 MB	Judgeable
Minimum Spanning Tree Redrawing GameGiven a connected weighted graph, find the expected number of MSTs that can be redrawn after each weight class is randomly erased with probability 1/x.	Hard9	Minimum spanning treeCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Good Luck in Your Service, HaneulCount the length-K sequences of member assignments that return all N bulbs to off, where each member's switches act as a fixed vector over the three bulb states.	Hard9	MathCombinatorics+1	No attempts yet	0.5s	1024 MB	Judgeable
IslandGiven an N-gon with non-crossing diagonals, find the fewest incenter insertions so the graph contains two edge-disjoint spanning trees.	Hard9	GraphDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
On the GridGiven an N by N grid with one blocked cell per row and column, report the shortest path from B1 to A4 after each row or column swap.	Hard9	MatrixShortest path+1	No attempts yet	2s	512 MB	Judgeable
Bit Counting SequenceGiven a sequence a of n values, find the smallest x >= 0 whose popcounts for x, x+1, ..., x+n-1 match a, or report -1 if none exists.	Hard9	Bit manipulationMath+1	No attempts yet	2s	1024 MB	Judgeable
Highway TollsFind the minimum total toll from city 1 to city N on one-way highways, where each toll adds K times the absolute value of the departure time.	Hard9	GraphShortest path+1	No attempts yet	4s	1024 MB	Judgeable
Marathon Race 2Given N balls on a road of length L, for each query (start S, goal G, limit T) decide whether one can collect all balls from S and end at G within T seconds.	Hard9	GreedyPrefix sum+1	No attempts yet	1.5s	1024 MB	Judgeable
LepezeUnder flip operations on a polygon triangulation, report the fewest flips needed to reach the fan at vertex x and how many shortest flip sequences exist.	Hard9	CombinatoricsTree+1	No attempts yet	2s	1024 MB	Judgeable
RobotsOn a wrapping board with left and right turn fields, find the fewest turns for a robot to get from a start cell to a goal cell for each query, or -1 if impossible.	Hard9	GraphShortest path+1	No attempts yet	2s	1024 MB	Judgeable
Sandpile on CliqueGiven a clique with chip counts on each vertex, determine whether toppling never stops; if it stops, output the final chip count of every vertex.	Hard9	MathSorting+1	No attempts yet	1s	1024 MB	Judgeable
Permutation GroupGiven k permutations, find the average number of inversions over all permutations in the group they generate, modulo 1e9+7.	Hard9	CombinatoricsMath	No attempts yet	15s	1024 MB	Judgeable
Interleaving SequencesGiven sequences A and B, count for each x the pairs of intervals A' and B' whose minimum interleaving stability equals x.	Hard9	ArrayTwo pointers+1	No attempts yet	9s	1024 MB	Judgeable
Desant 3For each k, count the initial ready/unready rows with k ready soldiers that end with all ready soldiers contiguous after the conditional swaps, modulo 2.	Hard9	Bit manipulationCombinatorics+1	No attempts yet	4s	1024 MB	Judgeable
Colorful ForestMaintain a dynamic forest with edge additions and removals, repaint every vertex within distance z of v to a color k, and report the current color of a given vertex.	Hard9	TreeGraph+1	No attempts yet	8s	1024 MB	Judgeable
LadybugCount the distinguishable escape routes from cell (I, 1) to the exit in each row, where two routes match if they visit the same cells and have the same first-visit rows per column.	Hard9	Dynamic programmingMatrix+1	No attempts yet	2s	512 MB	Judgeable
ScheduleSchedule one member per team each week so every pair of people from different teams meets, minimizing the longest gap between their meetings.	Hard9	CombinatoricsBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
A Recurring ProblemGiven n, find the n-th positive linear recurrence by generated terms (ties by coefficients) and print its coefficients, start values, and next 10 terms.	Hard9	MathBinary search+1	No attempts yet	20s	1024 MB	Judgeable
MeowCount chains of nodes with values 1 through L where each node is an ancestor of the next, under point value updates, and output the weighted sum of answers over all queries.	Hard9	TreeDynamic programming+2	No attempts yet	0.5s	1024 MB	Judgeable