Problems

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Total results29,392 problems

Combostone
Hard8
Implementation, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Linearization
Hard8
Bit manipulation, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Equal Maximums
Hard8
Array, Stack+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pandemic 2
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Heavy Burger
Hard8
Segment tree, String matching+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Fair Meeting
Hard8
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Nationwide tour
Hard8
Graph, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
3-Minute Graph Returns
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Relay Course Selection
Hard8
Array, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bus
Hard8
Simulation, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Koosaga's problem
Hard8
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
«Exclusive or» Strikes Back
Hard8
Bit manipulation, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Speeding
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ATM
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Posters
Hard8
Dynamic programming, Segment tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ikebana
Hard8
Dynamic programming, Stack+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Quadtree
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Traffic light
Hard8
Binary search, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Machine Learning
Hard8
Bit manipulation, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Garland
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cool Desks
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Idea Search
Hard8
String matching, String+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Rectangles
Hard8
Matrix, Stack+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Broken Line 04
Hard8
Sorting, Greedy+2
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
Broken Line 05
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
Broken Line 08
Hard8
Sorting, Greedy+2
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
Sky Walking
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Handcrafted Gift
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Painting Squares
Hard8
String, Combinatorics+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Connecting Supertrees
Hard8
Graph, Union-find+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Carnival Tickets
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Counting Mushrooms
Hard8
Implementation, Math+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Stations
Hard8
Tree, DFS+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Invasion War
Hard8
Union-find, Simulation+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Sea Battle
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Turtles in the Pond
Hard8
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Zoo Walk
Hard8
Graph, Topological sort+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Painting the Fence
Hard8
Greedy, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rotating Plate
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Exam
Hard8
Greedy, Array+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Strange City
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Advertisement Matching
Hard8
Math, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Economic One-way Roads
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
LCS 8
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Min-hashing
Hard8
Graph, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Remote Control
Hard8
Simulation, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Steel Slicing 2
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bit String
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Broken Tiles
Hard8
Binary search, Greedy+1
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Coronavirus Trend
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Trading System
Hard8
Heap, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Counting the Number of Trees
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Werewolf
Hard8
Graph, Union-find+1
No attempts yet
Time limit
4s
Memory limit
537 MB
Judgeable
Nowruz 2
Hard8
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nowruz 3
Hard8
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nowruz 9
Hard8
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nowruz 10
Hard8
Graph, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Toy Train
Hard8
Graph, Game theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shortcut
Hard8
Binary search, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Aliens
Hard8
Dynamic programming, Binary search
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cup of Jamshid
Hard8
Bit manipulation, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Last Supper
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pebbling Odometer 2
Hard8
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Card Shuffle
Hard8
Implementation, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Vista 1
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
0.1s
Memory limit
128 MB
Judgeable
Vista 2
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
0.1s
Memory limit
128 MB
Judgeable
Vista 7
Hard8
Geometry, Greedy+1
No attempts yet
Time limit
0.1s
Memory limit
128 MB
Judgeable
Tree and Queries 18
Hard8
Tree, Segment tree+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Hero Loves Powers of Two! Hero Loves Powers of Two!
Hard8
Bit manipulation, Greedy+2
No attempts yet
Time limit
2.2s
Memory limit
222 MB
Judgeable
Since It Has Come to This, Become the Memorization King
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dessert Café
Hard8
Tree, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Imprecise Computer
Hard8
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Switches
Hard8
Math, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bubble Bubble
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Colorful Square
Hard8
Binary search, Sliding window+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Border Robot
Hard8
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
3D Histogram
Hard8
Array, Divide and conquer+1
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Trees Hate Queries~
Hard8
Segment tree, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Icpcan Alphabet
Hard8
Dynamic programming, Brute force+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Keima
Hard8
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Nunchucks Shop
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Make Numbers
Hard8
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Quality Monitoring
Hard8
Graph, Backtracking+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Optimization for UltraNet
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Critical Structures
Hard8
Graph, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Save lives or money
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Bad-hash students
Hard8
Math, Number theory+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Dance of Divisibility
Hard8
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Interactivity
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Machine Gun
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Candy Delivery
Hard8
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Phone Friends
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
SPC Cake
Hard8
Geometry, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cups and Ball
Hard8
Implementation, Simulation+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
The Second Part
Hard8
Geometry, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Classic Quarantine
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bidirectional Code
Hard8
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Late Party
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flood
Hard8
Graph, Heap+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Treasure Hunt
Hard8
Tree, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
CombostoneGiven n turns of summon, buff, copy, and fight actions, output for each creature the turn it dies, or -1 if it is still alive at the end.	Hard8	ImplementationBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
LinearizationFor each query substring whose length is a power of two, find the minimum number of contiguous flips that make it a parity-of-AND pattern; the answer reduces to half the number of adjacent differing pairs after an XOR derivative.	Hard8	Bit manipulationPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Equal MaximumsCount quadruples of indices i<=j<k<=l where the maximum of a[i..j] equals the maximum of a[k..l], modulo 1e9+7, for n up to 100000.	Hard8	ArrayStack+2	No attempts yet	1s	512 MB	Judgeable
Pandemic 2On a weighted tree where some vertices start infected and the infection spreads along edges at speed one, find the maximum number of uninfected connected components that ever exist at one moment.	Hard8	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Heavy BurgerMaintain a string of parentheses under range flips, and for each query on a substring report the minimum number of characters to insert so the substring becomes a balanced parenthesis sequence.	Hard8	Segment treeString matching+2	No attempts yet	3s	1024 MB	Judgeable
Fair MeetingFill in the unknown integer distances so that no triangle has a unique smallest edge, minimizing the total, or report -1 if impossible.	Hard8	GraphUnion-find+1	No attempts yet	2s	1024 MB	Judgeable
Nationwide tourFind a Hamiltonian cycle in a complete graph with two edge colors that changes color at most once, asking at most 2N edge color queries.	Hard8	GraphImplementation	No attempts yet	1s	1024 MB	Judgeable
3-Minute Graph ReturnsGiven weighted intervals where overlapping ones share an edge, find the maximum total flavor of vertices kept so that the remaining graph has no cycles.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	3s	1024 MB	Judgeable
Relay Course SelectionCount pairs of rows S at most T such that a right-and-down path joins (S,1) to (T,M) through cells where A_i + B_j is at least 0.	Hard8	ArrayDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
BusSimulate bus boarding with passengers sitting in the closest free seat or standing over an occupied one, and choose Anton's seat minimizing the total time someone stands over him.	Hard8	SimulationGreedy+2	No attempts yet	2s	512 MB	Judgeable
Koosaga's problemCount the edge subsets of size at most two that make the connected graph bipartite, where no smaller removal set also works.	Hard8	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
«Exclusive or» Strikes BackFor each query with a and n up to 1e18, find the smallest non-negative b such that a xor b is divisible by n.	Hard8	Bit manipulationNumber theory+2	No attempts yet	2s	512 MB	Judgeable
SpeedingGiven n road segments with speed limits and lengths, plus m speeding ranges with fines, find for each car the maximum fine guaranteed from its entry and exit times.	Hard8	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
ATMFor each bound b, find the amount up to b that makes the greedy banknote algorithm dispense the most notes, and report that count.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
PostersOn a cycle of n posters, choose a subset with no run of four consecutive chosen positions, maximizing total colorfulness, and answer after each of q point updates.	Hard8	Dynamic programmingSegment tree+2	No attempts yet	2s	512 MB	Judgeable
IkebanaGiven n shoots that start at a_i and grow b_i per night, find the fewest range trims that make every shoot exactly h at noon on day m, or -1.	Hard8	Dynamic programmingStack+1	No attempts yet	2s	512 MB	Judgeable
QuadtreeGiven a 2^n by 2^n binary matrix and a budget k, flip at most k entries so the resulting matrix has a quadtree with the fewest possible cells.	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Traffic lightGiven two one-way roads with cars at known distances and speeds, choose a green and red split of a fixed period x that keeps the peak number of waiting cars as low as possible.	Hard8	Binary searchSorting+1	No attempts yet	2s	512 MB	Judgeable
Machine LearningCount length-n arrays with values from 0 to k where each value is a submask of every later value, and the given index pairs must differ, modulo 1e9+7.	Hard8	Bit manipulationCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
GarlandDelete elements from a binary string so the remaining string is beautiful (beads left of each 1 equal beads right of it, bounded by neighboring 1s), maximizing length.	Hard8	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Cool DesksBuy n two-seat desks from k height-range types and seat each group's 2n students in pairs to minimize the total discomfort across all groups.	Hard8	GreedySorting+1	No attempts yet	2s	512 MB	Judgeable
Idea SearchGiven blocks that append literal strings or copy earlier substrings of the growing text, count how many times pattern p occurs in the final text.	Hard8	String matchingString+1	No attempts yet	5s	1024 MB	Judgeable
RectanglesCount the rectangles of interior cells where every cell is strictly lower than the four neighboring cells just outside the rectangle in its row and column.	Hard8	MatrixStack+1	No attempts yet	5s	1024 MB	Judgeable
Broken Line 04Construct an axis-aligned broken line starting at the origin that passes through every given dot, minimizing the number of segments for partial credit.	Hard8	SortingGreedy+2	No attempts yet	0.1s	512 MB	Judgeable
Broken Line 05Given n points with distinct x and y coordinates, build a horizontal/vertical polyline from the origin covering all points, minimizing the number of segments.	Hard8	GreedySorting+2	No attempts yet	0.1s	512 MB	Judgeable
Broken Line 08Output-only task: build a horizontal and vertical broken line from the origin that touches every given dot, minimizing the number of segments for partial score.	Hard8	SortingGreedy+2	No attempts yet	0.1s	512 MB	Judgeable
Sky WalkingFind the shortest path length from the bottom of building s to the bottom of building g using buildings and skywalks, or report that no such path exists.	Hard8	Shortest pathGraph+2	No attempts yet	4s	1024 MB	Judgeable
Handcrafted GiftColor n beads red or blue so that every given interval contains exactly x[i] distinct colors (x[i] is 1 or 2), or report that no coloring works.	Hard8	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Painting SquaresPaint squares black or white and choose the smallest k so that the color pattern in any window of length k, together with whether it runs off the row, always identifies the window's start.	Hard8	StringCombinatorics+2	No attempts yet	4s	1024 MB	Judgeable
Connecting SupertreesGiven an n by n matrix of path counts (each 0 to 3), build a simple undirected graph of bridges that matches every p[i][j], or report that none exists.	Hard8	GraphUnion-find+1	No attempts yet	1s	1024 MB	Judgeable
Carnival TicketsGiven n sorted lists (n even), choose k disjoint transversal sets of one element per list to maximize the sum over rounds of the minimized total absolute deviation from a best center b.	Hard8	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Counting MushroomsGiven that mushroom 0 is species A, use a machine that counts adjacent differing pairs in a queried row to determine how many of the n mushrooms are species A.	Hard8	ImplementationMath+2	No attempts yet	2s	1024 MB	Judgeable
StationsLabel the stations of a tree so that a station holding a packet can pick the correct next hop knowing only its own label, the target label, and its neighbours' labels.	Hard8	TreeDFS+2	No attempts yet	20s	1024 MB	Judgeable
Invasion WarGiven an N by N grid of nations with soldiers, answer the soldier count of a queried territory's nation as daily battles, conscription, and territory expansion occur.	Hard8	Union-findSimulation+1	No attempts yet	3s	512 MB	Judgeable
Sea BattleTwo fleets of point ships move on an infinite grid at periodic step intervals; find the earliest step at which any ship from one fleet shares a cell with any ship from the other, or -1.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Turtles in the PondGiven a growing connected set of grid cells, after each insertion decide whether every pair can be joined by a path that uses only two fixed directions of movement.	Hard8	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Zoo WalkGiven a directed graph whose edge labels are partly wrong and a list of routes as label sequences, find two labels to swap so every route becomes a valid path.	Hard8	GraphTopological sort+1	No attempts yet	2s	512 MB	Judgeable
Painting the FenceGiven n segment lengths on a cyclic fence of k boards, order the painters and place each segment to maximize the minimum number of boards each painter is first to paint.	Hard8	GreedyBinary search+2	No attempts yet	2s	512 MB	Judgeable
Rotating PlateGiven a simple polygon pinned at its first vertex, find for each of m external points the maximum clockwise and counterclockwise rotation before the polygon hits that point.	Hard8	GeometryBinary search+2	No attempts yet	2s	512 MB	Judgeable
ExamGiven how many students were credited for each task, find the minimum number of bad students who copied to produce those counts.	Hard8	GreedyArray+1	No attempts yet	2s	512 MB	Judgeable
Strange CityChoose a subset of edges in an undirected graph so that every vertex has odd degree, or report that no such subset exists.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Advertisement MatchingAfter each update, check whether all ads can be delivered so that no recipient gets two ads from the same advertiser.	Hard8	MathCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
Economic One-way RoadsGiven N up to 18 cities with a directed cost for each road direction, orient every road so all cities are mutually reachable at minimum total cost, or report -1.	Hard8	GraphDynamic programming+1	No attempts yet	5s	1024 MB	Judgeable
LCS 8Count the length-N uppercase strings T whose LCS with S is at least N minus K, modulo 1e9+7, where K is at most 3.	Hard8	Dynamic programmingString+1	No attempts yet	3s	1024 MB	Judgeable
Min-hashingGiven a graph with a distinct label per node, repeatedly replace each node's value by the minimum value among its neighbors and find the largest number of node pairs sharing a value at any iteration.	Hard8	GraphSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Remote ControlGiven one blocked cell at the origin and a fixed command string of N moves, find the final cell for each of Q starting positions.	Hard8	SimulationPrefix sum+2	No attempts yet	2s	1024 MB	Judgeable
Steel Slicing 2Given a histogon of width N made from two mirrored histograms, find the fewest axis-parallel cuts that split it into rectangles.	Hard8	GeometryGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Bit StringCount bit strings of length n that contain P1 as a substring but avoid P2, modulo 1,000,000,007.	Hard8	Dynamic programmingString matching+2	No attempts yet	1.5s	1024 MB	Judgeable
Broken TilesGiven a rectangle split by a monotone rectilinear curve, find the largest possible minimum side length among rectangles from a rectangular cut of both pieces.	Hard8	Binary searchGreedy+1	No attempts yet	0.5s	512 MB	Judgeable
Coronavirus TrendFind the length of the longest subsequence of distinct integers in which every maximal increasing or decreasing run has length at least 3.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	2s	512 MB	Judgeable
Trading SystemGiven n integers and k, list the k largest sums among all contiguous subarrays, in non-increasing order.	Hard8	HeapPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Counting the Number of TreesCount, modulo 1e9+7, the binary search trees on keys 1..N that the insertion procedure can produce with height at most K.	Hard8	Dynamic programmingTree+2	No attempts yet	2s	256 MB	Judgeable
WerewolfFor each trip, decide whether a route from S to E exists that switches form at a city in [L, R], staying at or above L before the switch and at or below R after it.	Hard8	GraphUnion-find+1	No attempts yet	4s	537 MB	Judgeable
Nowruz 2Given a grid with rocks, block some free cells with bushes so the remaining free cells form a tree with as many degree-one cells as possible.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 3Turn a grid with rocks into a tree-shaped maze by blocking cells with bushes so that many free cells have exactly one free neighbor.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 9Given a grid with rocks, plant bushes so the remaining free cells form a tree, maximizing the number of cells that have exactly one free neighbor.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Nowruz 10Output-only task: given a grid with rocks, plant bushes so the free cells form a tree, maximizing the number of free cells with exactly one free neighbor.	Hard8	GraphTree+2	No attempts yet	1s	512 MB	Judgeable
Toy TrainOn a directed graph with charging stations, two players alternately fix the outgoing edge of each newly visited vertex; decide for every start whether Arezou can force the train to keep moving forever.	Hard8	GraphGame theory+2	No attempts yet	2s	512 MB	Judgeable
ShortcutGiven a main railway line with side branches, add one express edge of length c between two main stations so the network diameter is as small as possible.	Hard8	Binary searchTwo pointers+1	No attempts yet	2s	512 MB	Judgeable
AliensChoose at most k squares whose opposite corners lie on the grid diagonal so every cell with a point is covered, minimizing the total number of covered cells.	Hard8	Dynamic programmingBinary search	No attempts yet	2s	512 MB	Judgeable
Cup of JamshidFind a hidden point in a square using queries that return \|x-p\| XOR \|y-q\| for chosen points, staying within a query budget.	Hard8	Bit manipulationBinary search+2	No attempts yet	1s	512 MB	Judgeable
Last SupperWrite two programs: one reads the request sequence and outputs a short bit string, the other uses only that string plus online requests to make optimal eviction choices.	Hard8	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
Pebbling Odometer 2Write a program that ends on (0, 0) if x is at most y and on (0, 1) otherwise, leaving both pebble counts unchanged.	Hard8	SimulationImplementation	No attempts yet	1s	512 MB	Judgeable
Card ShuffleGiven an odd deck size N and positions A and B, find the shortest sequence of X and Y shuffles that moves the card at position A to position B.	Hard8	ImplementationMath+2	No attempts yet	1s	256 MB	Judgeable
Vista 1Given up to a million points in the plane, output a cyclic tour that visits every point once and returns to the start, judged by total Euclidean length.	Hard8	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 2Given up to a million points in the plane, output a cyclic tour visiting every point whose total Euclidean length is at most a constant factor times the optimal tour.	Hard8	GeometryGreedy+2	No attempts yet	0.1s	128 MB	Judgeable
Vista 7Given up to 1,000,000 points in the plane, find a closed tour visiting every point once, with the total Euclidean length kept short.	Hard8	GeometryGreedy+1	No attempts yet	0.1s	128 MB	Judgeable
Tree and Queries 18Given a tree, support adding 1 to a rerooted subtree, adding 1 along a path, and querying the sum of A_i times dist(v, i).	Hard8	TreeSegment tree+1	No attempts yet	5s	512 MB	Judgeable
Hero Loves Powers of Two! Hero Loves Powers of Two!Given up to 2.2M numbers, delete at most one, represent the rest as sums of distinct powers of two, XOR the resulting exponent sets, and print twice the maximum XOR value.	Hard8	Bit manipulationGreedy+2	No attempts yet	2.2s	222 MB	Judgeable
Since It Has Come to This, Become the Memorization KingAfter M rounds where a chosen student splits from their mentor and takes their whole subtree into a new group, answer K queries about whether two students share a group after round A.	Hard8	TreeDFS+2	No attempts yet	2s	1024 MB	Judgeable
Dessert CaféOn a weighted tree with k marked apartment nodes, count the nodes p for which some marked node z is strictly closer to p than to every other node.	Hard8	TreeGraph+2	No attempts yet	1s	512 MB	Judgeable
Imprecise ComputerGiven n and a sequence of n nonnegative integers, decide whether it can be the difference sequence of a double round-robin tournament played on {1,...,n} where each comparison may be answered arbitrarily when the two numbers differ by one.	Hard8	GreedyMath+1	No attempts yet	1s	512 MB	Judgeable
SwitchesGiven an N by N 0/1 matrix linking switches to lights, decide whether each light can be lit alone, and if so print the switches to press for every light.	Hard8	MathMatrix+2	No attempts yet	1s	512 MB	Judgeable
Bubble BubbleFor each index, replace that one element with any real number and report the minimum number of adjacent swaps bubble sort needs to sort the resulting array.	Hard8	SortingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Colorful SquareGiven colored points on a plane, find the smallest axis-aligned square that contains at least one point of every color.	Hard8	Binary searchSliding window+1	No attempts yet	5s	512 MB	Judgeable
Border RobotGiven N sensors on the barrier [0, L] with identification range r, find the minimum robot travel distance needed to move sensors so their intervals cover all of [0, L].	Hard8	GreedySorting	No attempts yet	1s	512 MB	Judgeable
3D HistogramGiven n blocks with heights a_i and lengths b_i, find the largest volume of a box over any run of adjacent blocks, where the box's height and length are the minimums of a and b over that run.	Hard8	ArrayDivide and conquer+1	No attempts yet	2.5s	512 MB	Judgeable
Trees Hate Queries~Maintain a sparse array over positions up to 1e9, apply range additions, and answer queries for the sum of a range after the first k updates.	Hard8	Segment treePrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Icpcan AlphabetCount the total orders on n letters that make two nested min/max expressions evaluate to the same letter.	Hard8	Dynamic programmingBrute force+2	No attempts yet	3s	512 MB	Judgeable
KeimaCount subsets of white points in an N by M grid that avoid knight-like pairs two rows apart, modulo 10^9+7.	Hard8	Dynamic programmingBit manipulation	No attempts yet	2s	512 MB	Judgeable
Nunchucks ShopGiven n and k, find the minimum number of binary strings of length n such that every length-n binary string pair with total k ones can be formed by joining two stored sticks, each usable in either orientation.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Make NumbersGiven four digits, count how many distinct non-negative integers can be formed by concatenating the digits in any grouping and order with +, -, and × under standard precedence.	Hard8	Brute forceImplementation+2	No attempts yet	1s	512 MB	Judgeable
Quality MonitoringFind the largest set of joints where no two are adjacent, and output -1 unless that set has at least n-28 joints.	Hard8	GraphBacktracking+1	No attempts yet	1s	1024 MB	Judgeable
Optimization for UltraNetChoose a spanning tree that first maximizes the minimum bandwidth on every tree path, then minimizes total edge weight, and output the sum over all city pairs of the bottleneck bandwidth along its path.	Hard8	GraphMinimum spanning tree+2	No attempts yet	3s	1024 MB	Judgeable
Critical StructuresGiven a connected undirected graph, count articulation points and bridges, group edges into biconnected components, and report the component count divided by the largest component size in lowest terms.	Hard8	GraphDFS+2	No attempts yet	3s	1024 MB	Judgeable
Save lives or moneyPick which gates to open so the flooded area is at least Area, saving the most residents and then losing the least money.	Hard8	TreeDynamic programming+1	No attempts yet	3s	1024 MB	Judgeable
Bad-hash studentsGiven n, k1, and alpha, count how many distinct cells the broken probe sequence k_i = k1 + alpha*k_{i-1}^2 mod n visits before it repeats.	Hard8	MathNumber theory+2	No attempts yet	5s	512 MB	Judgeable
Dance of DivisibilityCount the ways to perform K rotation moves between two circles of N dancers so that every couple's age sum has the same remainder mod M, modulo 1e9+7.	Hard8	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
InteractivityCount the minimum-size query sets that determine every node value in a rooted tree whose internal nodes are sums of their children, modulo 1e9+7.	Hard8	TreeDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Machine GunFor each query, find all enemies inside a right-facing angular wedge and evaluate a polynomial hash of their sorted indices; queries are forced online and the total number of hits is bounded.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Candy DeliveryOn a tree of N candy stores with five candy types, decide for each friend in order whether Yunjae, choosing his start freely, can walk a shortest path to the friend and pass a store selling the wanted candy.	Hard8	TreeDFS+2	No attempts yet	3s	1024 MB	Judgeable
Phone FriendsCount ordered distributions of K identical candies to N friends where each friend gets between m and M candies, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
SPC CakeChoose two lattice points A and B on the right and top edges with Manhattan distance L from the origin's corner rays, maximizing the total area of axis-aligned chocolates left uncut inside the wedge.	Hard8	GeometryPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Cups and BallGiven the N-1 observed cup swaps and pours, plus one missed move per query, find where a ball starting in cup s ends up after all N moves.	Hard8	ImplementationSimulation+2	No attempts yet	5s	1024 MB	Judgeable
The Second PartGiven n distinct points, find the minimum possible ratio of Manhattan distance to Euclidean distance over all pairs of points.	Hard8	GeometryDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
Classic QuarantineGiven a masked and unmasked count and n guests each with a mask threshold, find the minimum and maximum possible masked count after all guests enter in any order.	Hard8	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Bidirectional CodeGiven n up to 10^18, express it as a sum of at most 10 palindromic numbers and output the count and the palindromes.	Hard8	MathGreedy+2	No attempts yet	1s	512 MB	Judgeable
Late PartyOn an undirected weighted graph, find the longest prefix of your walk home during which at least one friend still shares some shortest path with you.	Hard8	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
FloodGiven a graph of Paris areas with altitudes and a rising Seine forecast, find the earliest time the Louvre (V1) gets positive water level.	Hard8	GraphHeap+1	No attempts yet	2s	512 MB	Judgeable
Treasure HuntGiven a tree grown online by adding paths, answer queries for the midpoint of the unique path between two points on a dynamic tree structure.	Hard8	TreeBinary search+1	No attempts yet	2s	512 MB	Judgeable