Problems

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Total results29,064 problems

DFS
Hard9
Tree, Union-find+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Village Planning
Hard9
Graph, Combinatorics+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Drinking Water
Hard9
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Battleship: New Rules
Hard9
Implementation, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Chocolate Programming Language
Hard9
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Don't Dodge the Money
Hard9
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Transmitter
Hard9
String matching, Two pointers+2
No attempts yet
Time limit
3s
Memory limit
1536 MB
Judgeable
Tourists
Hard9
Tree, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Lava Jump 2
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bandits
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Fun with Stones
Hard9
Combinatorics, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Park Trails
Hard9
Geometry, Graph+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Triangle
Hard9
Geometry, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Roll Call
Hard9
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Arbitration
Hard9
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Big Numbers
Hard9
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Game
Hard9
Math, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Just Another Edge
Hard9
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Khalin Graph
Hard9
Dynamic programming, Tree+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Moving Randomly
Hard9
Array, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ghost
Hard9
Graph, Tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sequence and Queries 42
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sumex
Hard9
Segment tree, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sequence, Intervals, and Queries
Hard9
Binary search, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Ryki
Hard9
Sorting, Prefix sum+2
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Polygons
Hard9
Number theory, Geometry+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Landing Raid
Hard9
Divide and conquer, Combinatorics+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Fibonacci Products
Hard9
Dynamic programming, String+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Territories
Hard9
Segment tree, Intervals+1
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Island
Hard9
Graph, Combinatorics+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Tekstówka
Hard9
Dynamic programming, String+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Royal Ball
Hard9
Graph, Union-find+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
A very complicated test
Hard9
Tree, DFS+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Arenas
Hard9
Graph, Union-find+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Desant 2
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
42s
Memory limit
1024 MB
Judgeable
Independent Sets
Hard9
Combinatorics, Tree+2
No attempts yet
Time limit
45s
Memory limit
1024 MB
Judgeable
Great Thermion Collider
Hard9
Dynamic programming, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Mines
Hard9
Tree, Divide and conquer+2
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Canvas
Hard9
Union-find, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Harsh Winter
Hard9
Dynamic programming, Segment tree+1
No attempts yet
Time limit
22s
Memory limit
1024 MB
Judgeable
IQ Game
Hard9
Probability, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fish Game
Hard9
Simulation, Sorting+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Indecisive Nikolaj
Hard9
Game theory, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Vacuum Cleaner
Hard9
Graph, Shortest path+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Sequence and Queries 43
Hard9
Segment tree, Math+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Interesting Weekend
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Big Challenges
Hard9
Intervals, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sports Day
Hard9
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Santa Claus
Hard9
Greedy, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Outer Ring Road 2
Hard9
Graph, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Picnic
Hard9
Bit manipulation, Math+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Score Betting
Hard9
Trie, String matching+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Typing Contest
Hard9
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Mana Collection
Hard9
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
GCD and K-th Query
Hard9
Binary search, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Kill switch (Hard)
Hard9
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Familiar Couples
Hard9
Union-find, Tree+1
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Goose, Goose, Ducks?
Hard9
Graph, Union-find+1
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Tree and Query 21
Hard9
Tree, DFS+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Tree and Query 22
Hard9
Tree, Binary search+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Tree and Query 23
Hard9
Tree, Divide and conquer+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Festivals in JOI Kingdom 2
Hard9
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
LaLa and Magic Circle (LiLi Version)
Hard9
Geometry, Simulation+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
LaLa and Magic Circle (LaLa Version)
Hard9
Geometry, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
LaLa and Monster Hunting (Part 2)
Hard9
Graph, Combinatorics+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
LaLa and Spirit Summoning
Hard9
Graph, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
The Answer to the Ultimate Question of Life, the Universe, and Everything
Hard9
Math, Number theory
No attempts yet
Time limit
0.42s
Memory limit
420 MB
Judgeable
Who Watches the Watchmen?
Hard9
Geometry, Graph+1
No attempts yet
Time limit
4s
Memory limit
2048 MB
Judgeable
Range Closest Pair of Points Query
Hard9
Divide and conquer, Geometry+1
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable
Greedy Bipartite Matching
Hard9
Graph, Greedy+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Forever Young
Hard9
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Endless Road
Hard9
Probability, Combinatorics+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Text Editor
Hard9
Tree, Implementation+1
No attempts yet
Time limit
1s
Memory limit
150 MB
Judgeable
Egor Has a Problem
Hard9
Array, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Matching on Tree Distance Graph
Hard9
Dynamic programming, Tree+1
No attempts yet
Time limit
5s
Memory limit
952 MB
Judgeable
Classical Data Structure Problem
Hard9
Segment tree, Array+1
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Sequence
Hard9
Array, Divide and conquer+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Nerd Sniping
Hard9
Math, Number theory
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Overgrown-Puzzled
Hard9
Simulation, Implementation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Japanese Lottery
Hard9
Dynamic programming, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Yet Another Problem on Empodia 2
Hard9
Array, Greedy+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Colored Points
Hard9
Geometry, Graph+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Stones
Hard9
Tree, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cell Automaton
Hard9
BFS, Math+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Signs on the Road
Hard9
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Connect
Hard9
Graph, DFS+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Mental Arithmetic
Hard9
Math, Number theory+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Active Preparation for the Battle
Hard9
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Jinx and the Peacekeeper Camp
Hard9
Segment tree, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Conflict of Interest
Hard9
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Dog, the Traitor, and the Cables
Hard9
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Help Prapor
Hard9
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Decorating Junhyeok's Windows
Hard9
Math, Matrix+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Crazy Assignments
Hard9
Matrix, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Black and White
Hard9
Graph, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Pandora's Box
Hard9
Dynamic programming, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
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

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
DFSGiven a rooted tree with vertex values, sum the expected minimum value on the random DFS stack over all legal pairs (x, y), modulo 998244353.	Hard9	TreeUnion-find+2	No attempts yet	8s	1024 MB	Judgeable
Village PlanningFor each N from 2 to M, sum the product of A[f(i,j)] over all labeled simple graphs on N houses, where f counts simple paths and at most K are allowed.	Hard9	GraphCombinatorics+1	No attempts yet	3s	1024 MB	Judgeable
Drinking WaterGiven n distinct values and up to k averaging operations on chosen subsets, find the maximum value h_1 can reach, printed to p decimal digits.	Hard9	Binary searchGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Battleship: New RulesOn an n by n board packed with ships, the second player must find any empty 2x2 square using at most 6n queries.	Hard9	ImplementationGreedy+1	No attempts yet	3s	1024 MB	Judgeable
Chocolate Programming LanguageWrite a Chocolate program, a two-dimensional esoteric language, that prints a staircase of stars with line i holding i stars for N up to 100.	Hard9	SimulationImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Don't Dodge the MoneyFind the minimum total key-press effort for Green to collect every coin falling on a grid, where left/right moves and jumps each have their own cost.	Hard9	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
TransmitterCount contiguous blocks of strings whose total pairwise longest common prefix length is at least K.	Hard9	String matchingTwo pointers+2	No attempts yet	3s	1536 MB	Judgeable
TouristsTourists on a tree move in index ranges to a chosen city, events add to the tourists in a city, and each query asks one tourist's opinion.	Hard9	TreeSegment tree+1	No attempts yet	4s	1024 MB	Judgeable
Lava Jump 2Count the ordered jump sequences, where each jump is at least twice the previous distance, that leave exactly one platform, after the initial setup and after each position change.	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
BanditsGiven a weighted tree of villages, add contracts that protect roads within distance R of a village, and report how many contracts protect a given road.	Hard9	TreeDivide and conquer+1	No attempts yet	5s	1024 MB	Judgeable
Fun with StonesGiven three pile ranges, find the probability Alice wins Nim with random pile sizes, modulo 1e9+7.	Hard9	CombinatoricsBit manipulation+2	No attempts yet	1s	1024 MB	Judgeable
Park TrailsGiven axis-parallel trails and an evacuation point, add the least-length tunnels so every point can reach the point by a path whose distance keeps shrinking.	Hard9	GeometryGraph+1	No attempts yet	3s	1024 MB	Judgeable
TriangleRecover the three integer vertices of a hidden triangle by querying lines and receiving the fraction of area each line cuts off.	Hard9	GeometryBinary search+1	No attempts yet	1s	1024 MB	Judgeable
Roll CallGiven N and Q queries, find the lexicographically smallest valid order of 2N roll calls with type x at position y, and output the weighted sum of positions modulo 1e9+7.	Hard9	CombinatoricsMath+1	No attempts yet	1s	256 MB	Judgeable
ArbitrationCount the ways to assign votes from 1 to k to the n-1 horizontal and m-1 vertical judges so every cell's signed sum matches the target grid, modulo 10^9+7.	Hard9	Dynamic programmingCombinatorics+1	No attempts yet	10s	1024 MB	Judgeable
Big NumbersGiven a rooted tree whose edge lengths are powers of 2, find the maximum total length of a trip from the root, modulo 998244353.	Hard9	TreeDynamic programming+2	No attempts yet	2s	1024 MB	Judgeable
GameGiven n players with values a_i, find the winner of a sequential mod-n game after each of q updates that set one a_x to y.	Hard9	MathArray+1	No attempts yet	2s	1024 MB	Judgeable
Just Another EdgeGiven a planar simple graph, count the non-adjacent vertex pairs whose new edge keeps the graph tripartite.	Hard9	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
Khalin GraphGiven a Halin graph through its base tree, count edge subsets where every connected component is a single vertex or a tree on 3 vertices, modulo 998244353.	Hard9	Dynamic programmingTree+2	No attempts yet	2s	1024 MB	Judgeable
Moving RandomlyFor each prefix, find the best expected score when a pointer starts at a random cell and may step left or right at random before stopping, modulo 998244353.	Hard9	ArrayGreedy+2	No attempts yet	2s	1024 MB	Judgeable
GhostGiven a tree plus a ring road through its leaves, build a tree decomposition with at most 4N bags of size 4 or less, each vertex's bags connected.	Hard9	GraphTree+1	No attempts yet	1s	1024 MB	Judgeable
Sequence and Queries 42Given a permutation A of length N, answer Q queries, each asking for the length of the longest increasing subsequence of A[l..r].	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
SumexGiven an array and q queries, find the sum of the mex (minimum excluded value) over every subarray inside each query range [l, r].	Hard9	Segment treeArray+1	No attempts yet	1s	1024 MB	Judgeable
Sequence, Intervals, and QueriesGiven a sequence, each query asks for the truncated maximum average of a subarray that starts in [a, b] and ends in [c, d].	Hard9	Binary searchPrefix sum+2	No attempts yet	5s	1024 MB	Judgeable
RykiFor each bear k, find where all bears end up when bear k never roars and stays put, then print the sum of row times column over all bears.	Hard9	SortingPrefix sum+2	No attempts yet	8s	1024 MB	Judgeable
PolygonsCount convex polygons on an X by Y lattice grid whose sides have no interior lattice points and integer length at most K, modulo 2^32.	Hard9	Number theoryGeometry+2	No attempts yet	10s	1024 MB	Judgeable
Landing RaidChoose k of n soldiers so the chosen subsequence of permutation a has the fewest inversions, then count the optimal choices for each k.	Hard9	Divide and conquerCombinatorics+1	No attempts yet	6s	1024 MB	Judgeable
Fibonacci ProductsGiven two positive integers in Zeckendorf form, print their product in the same Fibonacci representation. Total input length is up to 10^6 bits.	Hard9	Dynamic programmingString+1	No attempts yet	20s	1024 MB	Judgeable
TerritoriesEach territory can be placed in four ways on the torus. Find the largest area common to all territories after choosing one placement for each.	Hard9	Segment treeIntervals+1	No attempts yet	9s	1024 MB	Judgeable
IslandCount the subsets of sea-side settlements where ports can be built so that every lake-side settlement can reach at least one port, modulo 1e9+7.	Hard9	GraphCombinatorics+1	No attempts yet	6s	1024 MB	Judgeable
TekstówkaGiven strings s and t, answer q queries, each asking for the LCS length of a substring of s and a substring of t.	Hard9	Dynamic programmingString+1	No attempts yet	8s	1024 MB	Judgeable
Royal BallOn an n by n grid whose cells flip state, find after each flip the maximum number of hoop throws between performers in the same row or column.	Hard9	GraphUnion-find+1	No attempts yet	5s	1024 MB	Judgeable
A very complicated testGiven two BSTs on keys 1 to n, find the fewest rotations that turn one into the other without dropping a subtree, modulo 1e9+7, or -1.	Hard9	TreeDFS+1	No attempts yet	3s	1024 MB	Judgeable
ArenasFor each k, count ordered arena pairs (A, B) where buying a pass for A guarantees a forced win in B using only arenas numbered up to k.	Hard9	GraphUnion-find+1	No attempts yet	5s	1024 MB	Judgeable
Desant 2Given an array and k, answer range queries by finding the maximum sum of non-overlapping length-k blocks chosen inside each query range.	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	42s	1024 MB	Judgeable
Independent SetsCount unlabeled c-colored trees whose maximum independent set size is between l and r, modulo 998244353.	Hard9	CombinatoricsTree+2	No attempts yet	45s	1024 MB	Judgeable
Great Thermion ColliderCount the ways to turn each blue thermion into red or green so that the chain can react down to one thermion, and report this count after each point update.	Hard9	Dynamic programmingSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
MinesFor each vertex of a weighted tree, count how many mines explode when that mine is detonated, given that each blast reaches all mines within its radius along tree distance.	Hard9	TreeDivide and conquer+2	No attempts yet	9s	1024 MB	Judgeable
CanvasCount the color intervals [l, r] whose kept squares form exactly v connected regions on a two-row cylinder, for each v from 1 to k.	Hard9	Union-findSegment tree+1	No attempts yet	4s	1024 MB	Judgeable
Harsh WinterStations break and get repaired each day; find the least time for a plow starting at a given point to clear the whole road of length l.	Hard9	Dynamic programmingSegment tree+1	No attempts yet	22s	1024 MB	Judgeable
IQ GameGiven k remaining envelopes on a circle of n sectors, find the expected number of rounds until the Hyperblitz envelope is opened, modulo 998244353.	Hard9	ProbabilityCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Fish GameGiven fish moving left across a grid, find the maximum points a fish can eat while avoiding larger fish, over all starting rows.	Hard9	SimulationSorting+2	No attempts yet	3s	1024 MB	Judgeable
Indecisive NikolajEach starting cell of an N by M grid is a minimax game between alternating moves, and the task sums the resulting utilities over all cells modulo 998244353.	Hard9	Game theoryDynamic programming+2	No attempts yet	3s	1024 MB	Judgeable
Vacuum CleanerGiven an N by M grid where clearing a row or column resets its dust to zero, find the shortest path between two cells that only crosses cells with dust at most k.	Hard9	GraphShortest path+1	No attempts yet	3s	1024 MB	Judgeable
Sequence and Queries 43Given a sequence, answer point queries and apply range operations: conditional subtraction, arithmetic-progression assignment, and integer square root.	Hard9	Segment treeMath+1	No attempts yet	5s	1024 MB	Judgeable
Interesting WeekendGiven a triangular slide grid and n path flips, answer q queries for the lowest node from which two given nodes can both be reached through ridden pipes.	Hard9	TreeDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Big ChallengesFor each container x, find the maximum number of parts robots can place when every type 1 robot's range is extended to include x.	Hard9	IntervalsGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Sports DayGiven four teams of 15 soldiers with skills in three events, decide whether team A has a lineup that wins the overall title against every placement of the other teams.	Hard9	Game theoryDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Santa ClausFor each house i, find the minimum distance 2X_i - X_L Santa walks so that every elf gift can be handed to a child who accepts it.	Hard9	GreedySegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Outer Ring Road 2Choose roads of minimum total weight so that every odd-length simple cycle in the tree-plus-ring graph contains at least one chosen road.	Hard9	GraphTree+1	No attempts yet	2s	1024 MB	Judgeable
PicnicWizards on a round table write numbers over three rounds with limited visibility so that adjacent final numbers differ and stay below 40.	Hard9	Bit manipulationMath+1	No attempts yet	4s	1024 MB	Judgeable
Score BettingGiven prefix and suffix lists of scored strings with updates, find the max and min total score of any nonempty string over letters and digits.	Hard9	TrieString matching+2	No attempts yet	1s	1024 MB	Judgeable
Typing ContestGiven a 15-letter string and each contestant's press, left, and right costs, find the minimum typing time when the keys can be placed in any order on one row.	Hard9	Dynamic programmingBit manipulation+1	No attempts yet	2.5s	1024 MB	Judgeable
Mana CollectionGiven a directed graph of mana pools with collection rates, find the most mana collectable in s seconds while ending at pool e, for each query.	Hard9	Dynamic programmingBit manipulation+2	No attempts yet	5s	1024 MB	Judgeable
GCD and K-th QueryGiven a sequence of N positive integers, answer queries for the K-th smallest gcd over all subarrays inside a range [L, R].	Hard9	Binary searchNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Kill switch (Hard)Find the shortest array of 32-bit unsigned integers that a given buggy sorting implementation fails to sort, by reverse-engineering the hidden kill switch.	Hard9	ImplementationBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Familiar CouplesAfter each of q merge events on men or women, count the couple pairs connected in both DSUs, and output the sum of i times that count modulo 1e9+7.	Hard9	Union-findTree+1	No attempts yet	15s	1024 MB	Judgeable
Goose, Goose, Ducks?Find the fewest attendees who can be ducks so that goose statements fit all duck meetings and no duck statement contradicts earlier goose statements.	Hard9	GraphUnion-find+1	No attempts yet	Not set	1024 MB	Judgeable
Tree and Query 21Maintain a weighted tree under edge cut-and-link operations and report the total weight of the union of paths between each given vertex set.	Hard9	TreeDFS+1	No attempts yet	5s	1024 MB	Judgeable
Tree and Query 22Given a tree whose vertex values start equal to their indices, each query swaps two values and asks for the endpoint w that maximizes the path sequence from u, with queries encoded online.	Hard9	TreeBinary search+1	No attempts yet	10s	1024 MB	Judgeable
Tree and Query 23Given a tree and array A, answer online queries for the vertex that minimizes the weighted distance sum to indices l to r-1, with d as a heavy anchor.	Hard9	TreeDivide and conquer+2	No attempts yet	4s	1024 MB	Judgeable
Festivals in JOI Kingdom 2Count the pairs of sequences a and b of N intervals using each value from 1 to 2N once, where greedy selection by start time is not optimal, modulo prime P.	Hard9	Dynamic programmingCombinatorics+1	No attempts yet	6s	1024 MB	Judgeable
LaLa and Magic Circle (LiLi Version)Output a simple polygon of at most 1000 segments that needs between 120000 and 1000000 path reflections to become convex.	Hard9	GeometrySimulation+1	No attempts yet	10s	1024 MB	Judgeable
LaLa and Magic Circle (LaLa Version)Repeatedly reflect non-convex chains of a simple polygon until it is convex, then print its vertices counterclockwise from the lexicographically smallest one.	Hard9	GeometryImplementation	No attempts yet	2s	1024 MB	Judgeable
LaLa and Monster Hunting (Part 2)Count the subgraphs of a graph with up to 100,000 vertices and edges that are isomorphic to a fixed 6-vertex graph, modulo 998244353.	Hard9	GraphCombinatorics+1	No attempts yet	6s	1024 MB	Judgeable
LaLa and Spirit SummoningKeep at most one bar per color so the remaining spirit has the fewest planar degrees of freedom, and print that count.	Hard9	GraphGreedy+1	No attempts yet	3s	1024 MB	Judgeable
The Answer to the Ultimate Question of Life, the Universe, and EverythingGiven n, k, and the leading digit x of 2^n, count the powers of 2 up to 2^n whose leading digit is 4.	Hard9	MathNumber theory	No attempts yet	0.42s	420 MB	Judgeable
Who Watches the Watchmen?Reposition sentries so each one watches a different sentry and is watched by exactly one other, minimizing energy (1 per rotation, 1000 per move).	Hard9	GeometryGraph+1	No attempts yet	4s	2048 MB	Judgeable
Range Closest Pair of Points QueryGiven n points and q index ranges [l, r], find the squared distance of the closest pair of points inside each range.	Hard9	Divide and conquerGeometry+1	No attempts yet	9s	1024 MB	Judgeable
Greedy Bipartite MatchingFor each q, find the size of the greedy matching that uses edges of weight at most q in a bipartite graph whose edges arrive in weight layers.	Hard9	GraphGreedy+1	No attempts yet	10s	1024 MB	Judgeable
Forever YoungCount the ways to turn non-increasing array A into B in exactly k unit steps, where every intermediate array must also stay non-increasing.	Hard9	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Endless RoadThree chips start at a, b, c, and a random chip steps right each second. For each t up to n, print the expected maximum position modulo 998244353.	Hard9	ProbabilityCombinatorics+1	No attempts yet	10s	1024 MB	Judgeable
Text EditorImplement a text editor over a string up to 2^63 characters with insert, erase, cut, paste, undo, redo, and a two-run serialize step.	Hard9	TreeImplementation+1	No attempts yet	1s	150 MB	Judgeable
Egor Has a ProblemGiven a sorted array of distinct positive integers up to 1e18, find indices i<j<p<q with a_i * a_q = a_j * a_p, or report NO.	Hard9	ArrayHash map+1	No attempts yet	1s	1024 MB	Judgeable
Matching on Tree Distance GraphGiven a weighted tree, find the maximum total weight of a matching of size k in the complete graph where edge weights are tree distances, for every k.	Hard9	Dynamic programmingTree+1	No attempts yet	5s	952 MB	Judgeable
Classical Data Structure ProblemApply n range updates to an array of length 2^m, where each update adds i to a range and x grows by each new value; output x mod 2^30.	Hard9	Segment treeArray+1	No attempts yet	3s	128 MB	Judgeable
SequenceGiven an array of length N (up to 5 x 10^5), find the largest count of a median value over all subarrays, where the medians are the middle one or two sorted elements.	Hard9	ArrayDivide and conquer+1	No attempts yet	1.5s	1024 MB	Judgeable
Nerd SnipingGiven integer point (x,y) on an infinite grid of 1-ohm resistors, output the modular parts of the equivalent resistance from the origin to that point.	Hard9	MathNumber theory	No attempts yet	1s	1024 MB	Judgeable
Overgrown-PuzzledFind the starting cell on a ring of N cells with unknown icing types, using at most M moves and only a same-cell check after each move.	Hard9	SimulationImplementation+1	No attempts yet	3s	1024 MB	Judgeable
Japanese LotteryAfter each toggle of a horizontal bar in an Amida-kuji grid, find the fewest bars to remove so that every start leg reaches its matching prize.	Hard9	Dynamic programmingSegment tree+1	No attempts yet	4s	1024 MB	Judgeable
Yet Another Problem on Empodia 2Given the first k values of a permutation of length n, fill in the rest to maximize the number of framed intervals, then print the count and one optimal permutation.	Hard9	ArrayGreedy+1	No attempts yet	5s	1024 MB	Judgeable
Colored PointsGiven n points and t, classify each point as G, B, or R by whether the angular t-th successor process starts from it infinitely often, at least once, or never.	Hard9	GeometryGraph+1	No attempts yet	1s	1024 MB	Judgeable
StonesGiven a permutation, count the starting stones that make stone p turn white exactly at step k when each step takes the smallest-valued black neighbor.	Hard9	TreeDivide and conquer+1	No attempts yet	1s	1024 MB	Judgeable
Cell AutomatonBlack cells spread to adjacent white cells, then fade to gray and white over time. For each query time T, report how many cells are black.	Hard9	BFSMath+1	No attempts yet	6s	1024 MB	Judgeable
Signs on the RoadFind the lexicographically smallest digit string written while walking a graph to visit all towns, and the minimum toll for that string.	Hard9	GraphMinimum spanning tree+2	No attempts yet	2s	1024 MB	Judgeable
ConnectFor each city pair, find the lowest-numbered road whose closure breaks two-way reachability in a directed graph.	Hard9	GraphDFS+1	No attempts yet	2.5s	1024 MB	Judgeable
Mental ArithmeticGiven a sum-product expression and its claimed value modulo 10^9+7, find at most two changed digits that make it correct, or report NO.	Hard9	MathNumber theory+1	No attempts yet	4s	1024 MB	Judgeable
Active Preparation for the BattleGiven n people with strength p and alert cost c, for each query x find the minimum total alert cost needed to reach total strength at least x, or -1 if impossible.	Hard9	Dynamic programmingDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Jinx and the Peacekeeper CampGiven guard rectangles with strengths, find for each horizontal or vertical segment the minimum protection among its points that at least one guard covers.	Hard9	Segment treeSorting+1	No attempts yet	3s	1024 MB	Judgeable
Conflict of InterestCount ordered pairs of non-overlapping sub-rectangles in an H by W grid, each at most h tall and w wide, modulo 10^9+7.	Hard9	CombinatoricsMath	No attempts yet	2s	1024 MB	Judgeable
The Dog, the Traitor, and the CablesFind the maximum number of cable segments a dog can bite on a shortest path from (1,1) to each queried cell in a grid with cables.	Hard9	GraphBFS+2	No attempts yet	2s	1024 MB	Judgeable
Help PraporGiven an odd-length array of distinct integers, sum the maximum-weight perfect matching cost over all permutations, modulo 998244353.	Hard9	CombinatoricsMath+1	No attempts yet	1s	1024 MB	Judgeable
Decorating Junhyeok's WindowsCount the ways to pick a worker for each day so that N windows, each a tensor product of M vectors, end at the given light levels up to sign.	Hard9	MathMatrix+1	No attempts yet	1s	1024 MB	Judgeable
Crazy AssignmentsCount the 0/1 edge labelings of a tree so that the XOR of each given path is nondecreasing across the m paths in order, modulo 998244353.	Hard9	MatrixBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Black and WhiteCount the spanning trees of a wheel-shaped graph for each k, where k is the number of trees' roads controlled by the White gang.	Hard9	GraphDynamic programming+2	No attempts yet	5s	1024 MB	Judgeable
Pandora's BoxGiven n mountain heights, find the fewest segment operations on equal-height endpoints that make the heights nondecreasing, and list the segments in order.	Hard9	Dynamic programmingHash map+1	No attempts yet	2s	1024 MB	Judgeable
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