Problems

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Total results29,413 problems

Reservoir
Hard8
Binary search, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Artifact Restoration
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Broken Data
Hard8
Implementation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cat-First Search
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ants on a Circle
Hard8
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tourist
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Truth Tellers
Hard8
Array, Segment tree+2
No attempts yet
Time limit
3.5s
Memory limit
256 MB
Judgeable
Candy Boxes
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Dynamic Centroid
Hard8
Tree, DFS+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Raccoons Climb onto Jeongbo Island
Hard8
Number theory, Graph+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Raider Choragi and Queries (Normal)
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
SEGWAY
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Circular DNA
Hard8
Array, Stack+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Gosu
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Water Knows the Answers
Hard8
Array, Sorting+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Eat Economically
Hard8
Sorting, Greedy+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Increasing Sequence
Hard8
Dynamic programming, Binary search+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Alpine Valley
Hard8
Tree, Graph+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Tom's Kitchen
Hard8
Graph, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Olympiads
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Compound Escape
Hard8
Minimum spanning tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Whiskey Trade
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Outsider, You!
Hard8
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Decoration
Hard8
String, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Overflowing Popularity
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
The Valley Overflows
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Card Factory (Large)
Hard8
Sorting, Binary search+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Grid Query 2
Hard8
Segment tree, Math+1
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
NC String
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Making Everything White
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Superb Dart
Hard8
Geometry, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Enchanted Forest
Hard8
Graph, Divide and conquer+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Zoo
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Random Number Generator
Hard8
Simulation, Greedy+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Ticket Purchase
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Inner Product
Hard8
Matrix, Number theory+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Tree Count
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Highway Cycling
Hard8
Binary search, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Magic Chessboard
Hard8
Prefix sum, Number theory+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Lost In The Park
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rabbit Farming
Hard8
Matrix, Number theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ali's Typewriter
Hard8
String, Trie+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Super Piano
Hard8
Heap, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Altitude
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Modified Treap
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Plants vs. Zombies
Hard8
Graph, Topological sort+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pipe Marbles
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Masquerade Party
Hard8
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Course Design
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Olympic Logistics
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Candy Rain
Hard8
Segment tree, Simulation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Necklace Factory
Hard8
Segment tree, Array+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Counting Spanning Trees
Hard8
Matrix, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Network Charges
Hard8
Graph, Tree+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximum Profit
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
International Moonrabbit Organization
Hard8
Tree, Divide and conquer+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Third Baseman Unknown
Hard8
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Contests
Hard8
Intervals, Greedy+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Abbreviation
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Bracket Moves in Vim
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Union of Balls
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Society of the Dead Cactus
Hard8
Tree, Graph+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Maze
Hard8
Graph, Topological sort+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Binary Transformation
Hard8
Greedy, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Circumcenter of a Tree
Hard8
Tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Time Dragging
Hard8
Greedy, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sequence and Queries 24
Hard8
Segment tree, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
G++ Language
Hard8
Bit manipulation, Implementation+1
No attempts yet
Time limit
0.1s
Memory limit
256 MB
Judgeable
Overflowing Gift Cards
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Overflowing Banknotes
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Complaints Pile Up
Hard8
Binary search, Geometry+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
2xN Tiling with Queries
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Function Composition and Queries
Hard8
Binary search, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Kopo-bread Tournament
Hard8
Probability, Combinatorics+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Making a Flyswatter
Hard8
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fox Quiz
Hard8
Segment tree, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Transparent Crocodiles
Hard8
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Little Match Girl
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
kdh9949
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Deadly! 60-Note Combo
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hard To Explain
Hard8
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Good Set
Hard8
Bit manipulation, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cactus Determinant
Hard8
Graph, Tree+2
No attempts yet
Time limit
0.4s
Memory limit
1024 MB
Judgeable
Bohemian Rhaksody
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
6.5s
Memory limit
1024 MB
Judgeable
MST and Rectangles
Hard8
Minimum spanning tree, Prefix sum+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Tree Colors and Queries
Hard8
DFS, Tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Building Bridges 2
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sequence and Queries 25
Hard8
Segment tree, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence and Queries 28
Hard8
Segment tree, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Border
Hard8
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Expression Tree
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Hilbert's Hotel
Hard8
Math, Implementation+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Lexicographically Minimum Walk
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Maximizer
Hard8
Greedy, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Parklife
Hard8
Intervals, Shortest path+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
All You Need is Dating
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Choreography
Hard8
Greedy, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Steel Slicing
Hard8
Divide and conquer, Array
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Denouncing the Mafia
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Canyon Crossing
Hard8
Binary search, Graph+2
No attempts yet
Time limit
3.5s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
ReservoirGiven wall positions and heights and a volume K of water poured from the left, find the index of the last wall that water flows over for each query.	Hard8	Binary searchPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Artifact RestorationGiven a grid with some unknown cells, fill unknowns with 0 or 1 so that the total number of people summed over all subrectangles is divisible by K.	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Broken DataDelete some integers from a sequence so the rest reads as N M U1 V1 ... UM VM with 1 <= Ui,Vi <= N; among all valid restorations, maximize N, then M.	Hard8	ImplementationGreedy+2	No attempts yet	1s	512 MB	Judgeable
Cat-First SearchGiven a tree and the order Taehee wrote down in a cat-guided DFS, find the minimum number of cats and count their possible starting placements.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Ants on a CircleAnts move on a circle of N points, reversing on collision; for each query (P, X) find the earliest time point P has been visited at least X times.	Hard8	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
TouristGiven a weighted graph, for each city 2 through N find a shortest path from city 1, and count the minimum number of edges whose weights are re-photographed across all chosen paths.	Hard8	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Truth TellersGiven N people each stating a range for the number of truth tellers, find the maximum consistent truth-teller count after each of Q point updates.	Hard8	ArraySegment tree+2	No attempts yet	3.5s	256 MB	Judgeable
Candy BoxesGiven N boxes, each with m candies of sweetness a at cost c, find for every k from 1 to L the minimum price of boxes so that a subset of candies sums exactly to k.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1.5s	512 MB	Judgeable
Dynamic CentroidFor each prefix tree formed by vertices 1..k, output the smallest centroid (the vertex whose removal leaves components of size at most k/2).	Hard8	TreeDFS+2	No attempts yet	1.5s	512 MB	Judgeable
Raccoons Climb onto Jeongbo IslandFind the maximum number of raccoons that can eat cotton candy, tracking candy weights modulo K under form uniqueness and sticker costs.	Hard8	Number theoryGraph+1	No attempts yet	3s	512 MB	Judgeable
Raider Choragi and Queries (Normal)A donut-shaped ring of 2N zones holds prisoner counts that change over Q updates; after each change, print the minimum number of squads, each covering one zone or two adjacent zones with total at most W.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	5s	512 MB	Judgeable
SEGWAYSimulate N riders over a 300 m track with three speed sections and accelerators granting 1 s/m boost for X mod 20 meters, where X counts riders strictly ahead, and print each finish time.	Hard8	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Circular DNAGiven a circular sequence of start and end markers for many gene types, choose a cut position that maximizes how many gene types have their markers properly nested in the resulting linear subsequence.	Hard8	ArrayStack+2	No attempts yet	3s	512 MB	Judgeable
GosuGiven a tournament where each pair has a winner, find a vertex whose maximum shortest directed distance to every other vertex is as small as possible.	Hard8	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
Water Knows the AnswersGiven N boxes that may each be rotated, arrange them in a row to maximize the volume of water that stays trapped between them above the ground.	Hard8	ArraySorting+1	No attempts yet	3s	1024 MB	Judgeable
Eat EconomicallyFor each i from 1 to N, choose i lunch and i dinner menus from 2N distinct menus to minimize the total price, and print the N minimum totals.	Hard8	SortingGreedy+1	No attempts yet	3s	1024 MB	Judgeable
Increasing SequenceGiven a permutation, for each index i, count the indices j other than i whose removal shortens the longest increasing subsequence that contains i.	Hard8	Dynamic programmingBinary search+1	No attempts yet	3s	1024 MB	Judgeable
Alpine ValleyGiven a weighted tree with shops and an exit, answer queries where one edge is removed and you need either the shortest distance to the exit or to the nearest shop from a village.	Hard8	TreeGraph+2	No attempts yet	3s	512 MB	Judgeable
Tom's KitchenPick a subset of chefs so each meal gets at least K chefs working positive whole hours that sum exactly to A_i, minimizing the paid idle hours.	Hard8	GraphGreedy	No attempts yet	2s	512 MB	Judgeable
OlympiadsGiven N contestants with scores in K events, find the total score of the C-th best K-member team, where a team scores the per-event maximum over its members.	Hard8	Binary searchDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Compound EscapeCount the minimum-cost sets of gates in an N by K grid that connect every cell, modulo 10^9+7.	Hard8	Minimum spanning treeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Whiskey TradeModel the distribution network as a flow graph with node capacities and compute the maximum flow from Myeongjin to Jueun.	Hard8	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
Outsider, You!Given N and M, decide whether Junseo's motion can end up at seat M after a sequence of pointings, and if so, print one such pointing sequence.	Hard8	SimulationMath+1	No attempts yet	2s	512 MB	Judgeable
String DecorationGiven a string S and N pattern strings, find the length of the shortest substring of S that contains every pattern as a substring.	Hard8	StringSliding window+2	No attempts yet	2s	512 MB	Judgeable
Overflowing PopularityGiven M guests with arrival and departure times, choose when to insert up to K extra friends so that the count of ordinary attendees stays below T as long as possible.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
The Valley OverflowsGiven a tree of valleys with heights, decide whether water starting from any non-K valley can reach valley K under the splash-up movement rule.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Card Factory (Large)Each of N cards shows its front initially; given M queries K that flip every card whose visible number is at most K, report the final visible sum.	Hard8	SortingBinary search+2	No attempts yet	3s	256 MB	Judgeable
Grid Query 2Process up to 250,000 online queries on a 10^5 by 10^5 grid: add V to a rectangle, or return the rectangle's sum modulo 10^9+7, with each query decoded using the last printed answer.	Hard8	Segment treeMath+1	No attempts yet	15s	1024 MB	Judgeable
NC StringCount the permutations of chosen words (spaced apart) that contain an N before a later C, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Making Everything WhiteGiven an N by M black/white grid, choose for each cell one of three local color-inversion actions so that every cell ends up white, or report impossibility.	Hard8	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
Superb DartGiven a planar straight-line graph, list the areas of its bounded faces in increasing order, rounded to two decimals.	Hard8	GeometryGraph+2	No attempts yet	1s	512 MB	Judgeable
Enchanted ForestChoose a path from node 1 to node n minimizing the sum of the maximum a-value and maximum b-value over its edges.	Hard8	GraphDivide and conquer+2	No attempts yet	3s	512 MB	Judgeable
ZooGiven a string, count for each prefix the non-overlapping prefix-suffix matches and output the product of (count+1) modulo 1e9+7.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Random Number GeneratorSimulate a quadratic-polynomial generator to build a grid, then find the path from top-left to bottom-right whose sorted values are lexicographically smallest.	Hard8	SimulationGreedy+2	No attempts yet	3s	256 MB	Judgeable
Ticket PurchaseFor each city, find the minimum cost to reach root SZ by chaining tickets, where a ticket from v to ancestor a costs d*p_v+q_v and road distance d must be at most l_v.	Hard8	TreeDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
Inner ProductGiven n vectors of d nonnegative integers and a number k, find two vectors whose inner product is a multiple of k, or report that no such pair exists.	Hard8	MatrixNumber theory+1	No attempts yet	5s	512 MB	Judgeable
Tree CountGiven a DFS ordering and a BFS ordering of a rooted tree's vertices, find the average height over all rooted trees that produce both orderings.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Highway CyclingChoose a constant speed for each of N road segments so the total energy spent stays within EU and the total travel time is minimized.	Hard8	Binary searchMath+2	No attempts yet	1s	512 MB	Judgeable
Magic ChessboardGiven an N by M grid and a guardian cell, answer GCD queries over rectangles anchored at that cell while supporting rectangle range additions.	Hard8	Prefix sumNumber theory+2	No attempts yet	5s	512 MB	Judgeable
Lost In The ParkGiven a connected weighted graph with at most one cycle, find the expected total length of a random walk that never revisits a vertex, when the start vertex is chosen uniformly at random.	Hard8	TreeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Rabbit FarmingCount rabbit pairs in month n modulo p, where Fibonacci-style growth loses one pair whenever the total leaves remainder 1 when divided by k.	Hard8	MatrixNumber theory+1	No attempts yet	1s	512 MB	Judgeable
Ali's TypewriterGiven a keypress sequence that builds strings in a buffer and prints them, answer queries counting how often printed string x occurs inside printed string y.	Hard8	StringTrie+2	No attempts yet	1s	512 MB	Judgeable
Super PianoPick k distinct subarrays whose lengths lie between L and R, maximizing the total sum of their elements.	Hard8	HeapPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
AltitudeAssign altitudes to the intersections of an n by n grid so that total climbing energy over all directed street flows is minimized, with two corner altitudes fixed.	Hard8	Shortest pathGraph+2	No attempts yet	1s	512 MB	Judgeable
Modified TreapAssign new distinct priorities to tree nodes so that the Cartesian-tree shape minimizes weighted depth plus K times the number of changed priorities.	Hard8	Dynamic programmingTree+2	No attempts yet	1s	512 MB	Judgeable
Plants vs. ZombiesGiven a grid of plants, each with a score and an attack range, zombies enter from the right and can eat a plant only after clearing the plants to its right, but eating a plant that any surviving plant covers is fatal; maximize total score.	Hard8	GraphTopological sort+2	No attempts yet	1s	512 MB	Judgeable
Pipe MarblesGiven two binary strings as stacks, count the sum of squares of the number of interleavings producing each distinct output string, modulo 1024523.	Hard8	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Masquerade PartyGiven directed visibility edges between masks, find the maximum and minimum possible number of mask types k (at least 3) consistent with the observations.	Hard8	GraphUnion-find+2	No attempts yet	1s	256 MB	Judgeable
Course DesignPartition the cities into disjoint paths so the maximum number of coach edges on any city's route to the capital is minimized, then count the optimal partitions modulo Q.	Hard8	TreeDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
Olympic LogisticsGiven N stations that each point to a successor, change up to m successors to maximize R(1), where R(i) = C_i + k times the sum of R over i's predecessors.	Hard8	TreeDynamic programming+1	No attempts yet	1s	256 MB	Judgeable
Candy RainBouncing candy clouds of distinct colors drop candy over time, and each query counts the colors that fall inside a bag's range [L, R] at that moment.	Hard8	Segment treeSimulation+1	No attempts yet	2s	256 MB	Judgeable
Necklace FactorySimulate a necklace of N colored beads under rotate, flip, swap, and paint commands, and count the same-color runs in the whole necklace or in a segment.	Hard8	Segment treeArray+1	No attempts yet	3s	256 MB	Judgeable
Counting Spanning TreesCount spanning trees of a path graph where every pair of nodes at distance at most k is joined, k <= 5, n <= 10^15, modulo 65521.	Hard8	MatrixDynamic programming+2	No attempts yet	1s	256 MB	Judgeable
Network ChargesChoose plan A or B for each leaf of a perfect binary tree to minimize plan-change costs plus pairwise charges set by subtree majorities.	Hard8	GraphTree+1	No attempts yet	1s	256 MB	Judgeable
Maximum ProfitChoose relay stations to build so that revenue from served customer groups minus construction cost is maximized, where a group pays only if both of its stations are built.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	256 MB	Judgeable
International Moonrabbit OrganizationGiven a weighted tree, for each query (L, R, V) report the minimum, maximum, and sum of distances from base V to bases L through R.	Hard8	TreeDivide and conquer+2	No attempts yet	4s	1024 MB	Judgeable
Third Baseman UnknownOn an N by N grid of uppercase letters, walk right or down from the top-left to the bottom-right and maximize how many times "MOLA" appears in the collected string.	Hard8	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
ContestsGiven N contests as day intervals, find the fewest non-overlapping contests Hyeongseop can still win after K-1 rivals each pick a non-overlapping set of contests.	Hard8	IntervalsGreedy+1	No attempts yet	1.5s	1024 MB	Judgeable
AbbreviationCount the ways to split a query string into pieces, where each piece is a prefix of some dictionary word, with duplicates counted as distinct.	Hard8	Dynamic programmingString matching+2	No attempts yet	2.5s	1024 MB	Judgeable
Bracket Moves in VimGiven a bracket string with dots, find the minimum key presses to move the cursor between two positions, where h and l cost 1 and % costs 2 for each query.	Hard8	GraphShortest path+1	No attempts yet	5s	1024 MB	Judgeable
Union of BallsAll ball centers lie on the x-axis, so the union is a solid of revolution; compute its volume as p/q times pi and output p times q inverse mod 1e9+7.	Hard8	GeometrySorting+2	No attempts yet	2s	1024 MB	Judgeable
The Society of the Dead CactusGiven a cactus with vertex and edge recovery values, cut one edge from each cycle so the resulting tree has the smallest possible diameter, and print that diameter.	Hard8	TreeGraph+2	No attempts yet	4s	1024 MB	Judgeable
MazeGiven a grid where each cell forbids one direction, count the cells that lie on some walk from each query's start cell to its end cell, or print 0 if the end is unreachable.	Hard8	GraphTopological sort+1	No attempts yet	2s	1024 MB	Judgeable
Binary TransformationChoose a chain of N numbers from x0 to 0, each step clearing some 1 bits, so the set of adjacent differences has the smallest possible max minus min.	Hard8	GreedyBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Circumcenter of a TreeGiven a tree and many triples of vertices, for each triple report the unique vertex equidistant from all three (with equal distances as small as possible) or -1 if none exists.	Hard8	TreeGraph+2	No attempts yet	2s	512 MB	Judgeable
Time DraggingGiven an N by M board with marked cells, find the longest sequence of row and column picks such that no pick creates a marked intersection among chosen lines.	Hard8	GreedyGraph+2	No attempts yet	1s	512 MB	Judgeable
Sequence and Queries 24Maintain an array under point updates and range queries that ask for the largest sum of two distinct elements within a subarray.	Hard8	Segment treeDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
G++ LanguageWrite a G++ program that reads H and W, then leaves the sum of the cells in the rectangle from (a, b) to (c, d) in memory 0 and zeros elsewhere.	Hard8	Bit manipulationImplementation+1	No attempts yet	0.1s	256 MB	Judgeable
Overflowing Gift CardsGiven each card's days until expiry and the day he plans to use it, find the fewest 30-day extensions so every card is still valid when used, under a rule that he must always use the card closest to expiry.	Hard8	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Overflowing BanknotesFor each query, after updating one node, find the maximum banknotes that can be gathered at one safe when any node is chosen as root and the coins fall optimally.	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Complaints Pile UpFind the largest integer volume V so that each speaker's Manhattan-distance sound range, with radius V times its size, never overlaps another speaker's range.	Hard8	Binary searchGeometry+1	No attempts yet	5s	512 MB	Judgeable
2xN Tiling with QueriesMaintain the count of tilings of a 2xN grid by 1x2 and 2x1 tiles while cells get blocked and unblocked by queries.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	256 MB	Judgeable
Function Composition and QueriesGiven a function f on 1..m, answer queries n, x by returning the value of the n-fold composition f^n(x).	Hard8	Binary searchGraph+2	No attempts yet	1s	512 MB	Judgeable
Kopo-bread TournamentFor each rating range [A, B], find the expected number of values recorded in a random-order knockout tournament, as a value modulo 10^9+7.	Hard8	ProbabilityCombinatorics+1	No attempts yet	5s	1024 MB	Judgeable
Making a FlyswatterGiven a simple polygon, find the expected squared distance between two points chosen independently and uniformly inside it.	Hard8	GeometryMath+2	No attempts yet	1s	1024 MB	Judgeable
Fox QuizGiven answer strings S and T over O/X, answer range queries and point flips: for a range, choose positions to mark F to maximize A times correct answers plus B times occurrences of the consecutive pattern F,O,X.	Hard8	Segment treeDynamic programming+2	No attempts yet	3s	1024 MB	Judgeable
Transparent CrocodilesGiven claw mark counts at each swamp position, find the minimum total front-to-back paw distance of crocodiles that leave exactly those marks, or -1 if impossible.	Hard8	Dynamic programmingMath+1	No attempts yet	1s	1024 MB	Judgeable
The Little Match GirlChoose for each of N integers to skip it, multiply by its negative for 1 matchstick, or multiply by its positive value for 2 matchsticks, spending at most K, to maximize the product modulo 1e9+7.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
kdh9949Find the longest path in an undirected graph whose vertex labels spell repeated KDH blocks, or report -1 if such a path can be infinite.	Hard8	GraphDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Deadly! 60-Note ComboFor each query (a, b, c), count how many binary strings x with a <= x <= b score strictly higher than c in a 60-note combo game, where a GOOD after a combo of X gives 2X-1 points.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	1024 MB	Judgeable
Hard To ExplainGiven a rooted tree, answer queries for the minimum of A_i + B_i * T over the vertices on the path from the root to V whose C_i is at least T.	Hard8	TreeDFS+2	No attempts yet	3s	1024 MB	Judgeable
Good SetCount the nonempty subsets of {0, ..., 2^k - 1} that are closed under bitwise AND and OR and contain all given n integers, with k up to 7.	Hard8	Bit manipulationDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Cactus DeterminantGiven a connected cactus graph with up to 50000 vertices, find the determinant of its adjacency matrix modulo 993244853.	Hard8	GraphTree+2	No attempts yet	0.4s	1024 MB	Judgeable
Bohemian RhaksodyEach bulb lights one of four half-planes (x at most X, x at least X, y at most Y, or y at least Y), and the task is to find the largest area the bulbs light together.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	6.5s	1024 MB	Judgeable
MST and RectanglesGiven an N by N matrix updated by Q rectangle additions (mirrored across the diagonal), find the MST cost of the complete graph with edge weights A[i][j].	Hard8	Minimum spanning treePrefix sum+1	No attempts yet	8s	1024 MB	Judgeable
Tree Colors and QueriesA rooted tree where edges are deleted over time; after each deletion, count distinct colors among vertices still reachable from a queried vertex.	Hard8	DFSTree+2	No attempts yet	2s	256 MB	Judgeable
Building Bridges 2On a small grid, connect all islands with straight length-2+ bridges over sea so the total bridge length is minimized, or print -1.	Hard8	GraphMinimum spanning tree+2	No attempts yet	1s	512 MB	Judgeable
Sequence and Queries 25Maintain an array under range bitwise AND, range bitwise OR, and range maximum queries, each value below 2^20.	Hard8	Segment treeBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Sequence and Queries 28Maintain an array under range add, range floor-sqrt, and range sum queries, and report each range sum.	Hard8	Segment treeMath+2	No attempts yet	1s	512 MB	Judgeable
BorderGiven an N by N grid of species (N at most 4), find a non-self-crossing border path from the top-left to the bottom-right corner so that different species end up in separate regions, or report that none exists.	Hard8	GraphBrute force+2	No attempts yet	1s	256 MB	Judgeable
Expression TreeGiven a binary expression tree with + and - operators, permute the operand values freely to maximize the evaluated result.	Hard8	TreeGreedy+2	No attempts yet	1s	256 MB	Judgeable
Hilbert's HotelSimulate Hilbert's Hotel as guests arrive in finite or infinite groups, and answer which group occupies a room or which room holds a given index of a group.	Hard8	MathImplementation+2	No attempts yet	1.5s	1024 MB	Judgeable
Lexicographically Minimum WalkFind the lexicographically smallest color sequence among all walks from S to T of length at most 10^100, reporting IMPOSSIBLE or TOO LONG when needed.	Hard8	GraphGreedy+2	No attempts yet	2s	1024 MB	Judgeable
MaximizerGiven two permutations A and B of 1..N, find the minimum number of adjacent swaps in A needed to reach a permutation maximizing the sum of \|a_i - b_i\|.	Hard8	GreedyCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
ParklifeChoose bridges so that each arc between adjacent points is crossed by at most k chosen bridges, and find the maximum total value for every k from 1 to N.	Hard8	IntervalsShortest path+1	No attempts yet	1.5s	1024 MB	Judgeable
All You Need is DatingGiven bipartite preferences and per-student min/max date counts, find the maximum number of dates satisfying all lower and upper bounds, or -1.	Hard8	GraphDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
ChoreographyMembers on non-overlapping equal intervals move one at a time to an intersecting interval, and the task is to reach set E from set S in the fewest steps.	Hard8	GreedyShortest path+1	No attempts yet	2s	512 MB	Judgeable
Steel SlicingGiven each slab's heights above and below the x-axis, find the largest-area axis-aligned rectangle that fits inside the histogon.	Hard8	Divide and conquerArray	No attempts yet	2.5s	512 MB	Judgeable
Denouncing the MafiaGiven a rooted tree at node 1 and a limit K, choose up to K nodes to seed interrogations so the total number of reachable ancestors is maximized.	Hard8	TreeGreedy+2	No attempts yet	1s	512 MB	Judgeable
Canyon CrossingFind a path from the bottom row to the top row of a grid maximizing the minimum cell height, where up to K cells on the path can be crossed by bridges and ignored.	Hard8	Binary searchGraph+2	No attempts yet	3.5s	512 MB	Judgeable