Problems

Pick a problem, code in the editor, and watch the judge run real test cases. The archive is open to browse

Under construction

Still being built. Things may change

Total results29,234 problems

Primes and XOR? Nonsense
Hard8
Number theory, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Many LCS
Hard8
Combinatorics, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Cake
Hard8
Array, Greedy+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Median
Hard8
Divide and conquer, Dynamic programming+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Klee in Solitary Confinement
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ancient Magic Circle in Teyvat
Hard8
Graph, Combinatorics
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bipartite Barricade
Hard8
Bit manipulation, Dynamic programming+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Teleporters
Hard8
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Opening Offices
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Square Grid Puzzle
Hard8
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tree Infection
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Divide and Rule 2.0
Hard8
Number theory, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Connected dominating set
Hard8
Graph, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Hedgehog Graph 2
Hard8
Implementation, Math+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Macaron Kama
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bandwidth Management
Hard8
Tree, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
New Product Development
Hard8
Graph, Sorting+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Random Road
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Maximize the Average
Hard8
Array, Prefix sum+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Police and Thief
Hard8
Tree, Binary search+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Railway 2
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Missing Number
Hard8
String, Implementation+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Tip of Your Tongue
Hard8
String, Trie+1
No attempts yet
Time limit
4s
Memory limit
2048 MB
Judgeable
Books
Hard8
Bit manipulation, Dynamic programming
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Domino on Torus
Hard8
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
In the cube
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Inverse KMP
Hard8
String matching, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
IQ Test
Hard8
Dynamic programming, Segment tree
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Random Spanning Tree
Hard8
Minimum spanning tree, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tri-color Spanning Tree
Hard8
Graph, Matrix+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
XOr
Hard8
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dividing an orange
Hard8
Game theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Analyze This
Hard8
Sorting, Segment tree+1
No attempts yet
Time limit
3.5s
Memory limit
1024 MB
Judgeable
Quadruples of Points
Hard8
Geometry, Hash map+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Physics
Hard8
Implementation, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Shinchon Defense HQ: The Secret of the Underground Bunker
Hard8
Tree, Implementation+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Largest rectangle in a histogram and queries 2
Hard8
Stack, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
In-order
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
ABC String
Hard8
String, Greedy+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Acceptable Seating Arrangements
Hard8
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Range Editing
Hard8
Dynamic programming, Intervals
No attempts yet
Time limit
4s
Memory limit
2048 MB
Judgeable
1D Stone Game 2
Hard8
Game theory, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
I hate even numbers
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Merging Cells
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Walking in Manhattan
Hard8
Simulation, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cowmpetency
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Virus
Hard8
Tree, Shortest path+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Test Data Creation
Hard8
Graph, Matrix
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Attraction Score
Hard8
Graph, Brute force
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Tree Quiz
Hard8
Tree, DFS+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Garden 2
Hard8
Dynamic programming, Matrix+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Road Service 2
Hard8
Graph, Union-find+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Eggplant Field Path
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rightplant
Hard8
Array, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Eggplant Summoning Magic
Hard8
Geometry, Math+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Infection Simulation
Hard8
Intervals, Graph+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Target Practice II
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Moorbles
Hard8
Dynamic programming, Game theory+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Milk Exchange
Hard8
Simulation, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Special Dropkick 2
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bitovi
Hard8
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pirate Code
Hard8
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
So I'll Max Out My Constructive Algorithm Skills
Hard8
Matrix, Implementation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Link-Cut Tree
Hard8
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Colourful Tree
Hard8
Tree, Divide and conquer+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Bajtocja Village Modernization
Hard8
Segment tree, Implementation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Coins
Hard8
Game theory, Combinatorics+1
No attempts yet
Time limit
25s
Memory limit
1024 MB
Judgeable
UDP Stacks
Hard8
Stack, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hyper Tree Problem
Hard8
Bit manipulation, Union-find+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Fish 3
Hard8
Greedy, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Growing Vegetables is Fun 5
Hard8
Binary search, Greedy+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Card Collection
Hard8
Divide and conquer, Segment tree+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Escape Route 2
Hard8
Dynamic programming, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Island Hopping
Hard8
Tree, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Love is War
Hard8
Segment tree, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Fair Distribution
Hard8
Dynamic programming, Number theory+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Splitting Haybales
Hard8
Array, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Activating Robots
Hard8
Greedy, Binary search+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
The 'Winning' Gene
Hard8
String, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Phoenix That Topples the School
Hard8
Dynamic programming, Stack+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
V.I.P.
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Discount Event
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Virus Simulator
Hard8
Segment tree, Simulation
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Yunny's Trip
Hard8
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hula's Cardgame
Hard8
Game theory, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Carl's Vacation
Hard8
Geometry, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Three Kinds of Dice
Hard8
Probability, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Compression
Hard8
String matching, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fundamental Magic
Hard8
Segment tree, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Popcorn
Hard8
Intervals, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bfs
Hard8
Dynamic programming, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Revenge
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Strange Tree Hashing
Hard8
Tree, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Farm Land Split
Hard8
Geometry, Segment tree+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
1D Game
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Champernowne Substring
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
10s
Memory limit
2048 MB
Judgeable
Square of Triangles
Hard8
Geometry, Math+1
No attempts yet
Time limit
5s
Memory limit
2048 MB
Judgeable
Binary Tree
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tiles
Hard8
Dynamic programming, Geometry
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Minequake
Hard8
Tree, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Primes and XOR? NonsenseGiven L and R up to 1e12, count the integers that can be formed as the XOR of some subset of the primes in [L, R].	Hard8	Number theoryBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Many LCSGiven K, construct two binary strings of length at most 8848 that have exactly K distinct longest common subsequences.	Hard8	CombinatoricsDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
CakeGiven two 2 by n grids of colors, find the minimum number of 180-degree rotations of 2x2 blocks that turns the initial grid into the target, or report -1.	Hard8	ArrayGreedy+1	No attempts yet	10s	1024 MB	Judgeable
MedianCount the ways to fill the unknown values in a sequence so that the recursive three-way magicThrees procedure returns the true median, modulo 10^9 + 7.	Hard8	Divide and conquerDynamic programming+1	No attempts yet	5s	1024 MB	Judgeable
Klee in Solitary ConfinementGiven an array and an integer k, add k to at most one contiguous interval so that the mode of the whole array appears as many times as possible.	Hard8	SortingPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Ancient Magic Circle in TeyvatGiven a complete graph on n vertices with m red edges, find the absolute difference between the number of all-red 4-cliques and all-blue 4-cliques.	Hard8	GraphCombinatorics	No attempts yet	2s	1024 MB	Judgeable
Bipartite BarricadeCount the vertex subsets of a bipartite graph whose total weight is at least t and that some matching fully covers, with every subset vertex matched.	Hard8	Bit manipulationDynamic programming+1	No attempts yet	2.5s	1024 MB	Judgeable
TeleportersGiven teleporters with frequencies in [L, R], find the minimum possible maximum frequency gap for Anna and Beka to meet, or report that they cannot.	Hard8	Number theoryMath+1	No attempts yet	2s	1024 MB	Judgeable
Opening OfficesCount the ways to choose T office buildings on a grid so that the shortest closed tour is the same on the full grid and on the night spanning tree, modulo 1000000007.	Hard8	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Square Grid PuzzleSort an N by N grid into row-major order using moves that send the top row to the bottom or the left column to the right, in fewer than 3N moves.	Hard8	SimulationMatrix+1	No attempts yet	1s	1024 MB	Judgeable
Tree InfectionFor each vertex s in a rooted tree, count pairs (u, v) that stay mutually reachable after s and its descendants within distance R are infected.	Hard8	TreeDivide and conquer+1	No attempts yet	1s	1024 MB	Judgeable
Divide and Rule 2.0Given an array of distinct values, count the positions in each query range [l, r] whose value divides d or is a multiple of d.	Hard8	Number theoryPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Connected dominating setGiven an n by m grid graph, output a connected dominating set of at most nm/2 cells, or print NO if none exists.	Hard8	GraphMath+1	No attempts yet	2s	1024 MB	Judgeable
Hedgehog Graph 2Given up to 10 functional graphs shaped like a cycle with trees of depth 1, find each cycle length using at most 900 queries that jump x steps from a chosen vertex.	Hard8	ImplementationMath+1	No attempts yet	2.5s	1024 MB	Judgeable
Macaron KamaPair each red shell with a blue shell from the same multiset so each macaron takes the larger size, and maximize the resulting digit string if it is a palindrome.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Bandwidth ManagementGiven a tree with vertex limits and a queue of path-add reservations, find the longest prefix of reservations that keeps every vertex under its limit.	Hard8	TreePrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
New Product DevelopmentGiven a graph where edges unlock by a counter threshold, simulate K steps from vertex 1 and print the final vertex and counter modulo 1000000007.	Hard8	GraphSorting+2	No attempts yet	1.5s	1024 MB	Judgeable
Random RoadGiven a tree with park beauties and randomly oriented one-way snake edges, find the expected beauty of a safe random walk from each starting park, modulo 1e9+7.	Hard8	Dynamic programmingTree+2	No attempts yet	3s	1024 MB	Judgeable
Maximize the AverageGiven a sealed subarray A[i] to A[j], find the maximum average of any final sequence that removal operations can produce from it.	Hard8	ArrayPrefix sum+1	No attempts yet	5s	1024 MB	Judgeable
Police and ThiefGiven a tree of houses with road lengths, find how long a police officer at P (speed V1) takes to catch a thief starting at T (speed V2), for each of Q scenarios.	Hard8	TreeBinary search+1	No attempts yet	1.5s	1024 MB	Judgeable
Railway 2Given a weighted tree, sum the largest threshold D that lets you reach y from x using paths of length at least D, over all ordered pairs, mod 1e9+7.	Hard8	TreeDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Missing NumberGiven the digits of consecutive integers from a to b joined together with one integer removed, list every value that could have been the eaten number.	Hard8	StringImplementation+1	No attempts yet	2s	2048 MB	Judgeable
Tip of Your TongueGiven dictionary words, answer queries that count words with prefix p and suffix s (equal length) combined by AND, OR, or XOR.	Hard8	StringTrie+1	No attempts yet	4s	2048 MB	Judgeable
BooksFor each candidate pair of students, find every book set whose books the two students can jointly cover, splitting the books between them.	Hard8	Bit manipulationDynamic programming	No attempts yet	6s	1024 MB	Judgeable
Domino on TorusCount the valid white-black domino tilings of the outer surface of an A by B torus with a C by D rectangular hole cut out.	Hard8	CombinatoricsMath	No attempts yet	2s	1024 MB	Judgeable
In the cubePlace k tables on the 5001 by 5001 grid, away from the n stands, so the total of each table's distances to its c closest stands is minimal.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	3s	1024 MB	Judgeable
Inverse KMPGiven a string's KMP prefix-function array and the alphabet size c, count the strings that produce that array, modulo 1e9+7.	Hard8	String matchingCombinatorics	No attempts yet	1s	1024 MB	Judgeable
IQ TestGiven n questions whose options claim counts of earlier answers, find the maximum number of questions that can be answered correctly.	Hard8	Dynamic programmingSegment tree	No attempts yet	1s	1024 MB	Judgeable
Random Spanning TreeGiven a small connected graph with random uniform edge weights, the task is to compute the exact expected MST weight as a reduced fraction p/q.	Hard8	Minimum spanning treeMath+2	No attempts yet	1s	1024 MB	Judgeable
Tri-color Spanning TreeCount spanning trees of a three-colored graph with at most g green and at most b blue edges, modulo 1e9+7, for n up to 40.	Hard8	GraphMatrix+1	No attempts yet	2s	1024 MB	Judgeable
XOrSplit an array into exactly m consecutive parts so the OR of the parts' XOR sums is as small as possible, and print that minimum.	Hard8	Bit manipulationGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Dividing an orangeFor each wildcard rank, find the minimum and maximum number of oranges that person can get in the ranked voting game with n people and k oranges.	Hard8	Game theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
Analyze ThisFor each day with cooking time D, find the pair of customers whose handshake gives one of them the largest anger, where anger equals the time they have already waited.	Hard8	SortingSegment tree+1	No attempts yet	3.5s	1024 MB	Judgeable
Quadruples of PointsGiven n sets of four points and m axis-parallel rectangles, decide for each rectangle whether it contains exactly half of the points in every set.	Hard8	GeometryHash map+1	No attempts yet	5s	1024 MB	Judgeable
PhysicsGiven the max and min of two piecewise linear velocity graphs over time T, restore both graphs, each covering the same distance.	Hard8	ImplementationTwo pointers+1	No attempts yet	1s	1024 MB	Judgeable
Shinchon Defense HQ: The Secret of the Underground BunkerGiven a tree of buildings colored mint or purple, locate the one building holding a bunker using at most 30 color changes across two runs.	Hard8	TreeImplementation+1	No attempts yet	10s	1024 MB	Judgeable
Largest rectangle in a histogram and queries 2Given N histogram bars, answer Q queries asking for the area of the largest rectangle that fits inside bars l through r only.	Hard8	StackSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
In-orderCount the distinct in-order traversals of binary trees matching given pre-order, post-order, and partial in-order lists, modulo 999999937.	Hard8	TreeDivide and conquer+1	No attempts yet	1s	1024 MB	Judgeable
ABC StringPartition a string with equal counts of A, B, and C into the fewest subsequences, where each subsequence splits into consecutive triples that each contain one of every letter.	Hard8	StringGreedy+1	No attempts yet	1s	2048 MB	Judgeable
Acceptable Seating ArrangementsSwap students in a grid so every row stays increasing by height while turning the original seating into a target seating in at most 10^4 swaps.	Hard8	MatrixSimulation+1	No attempts yet	1s	2048 MB	Judgeable
Range EditingGiven a row of n cells with target values (0 means empty), find the minimum number of range assign and range clear operations to reach them.	Hard8	Dynamic programmingIntervals	No attempts yet	4s	2048 MB	Judgeable
1D Stone Game 2Two players take turns removing consecutive stones from a 1 by n row, with the move size capped by the previous move, and the task is to find the winner for each n.	Hard8	Game theoryMath+1	No attempts yet	1s	1024 MB	Judgeable
I hate even numbersFill an N by N grid with stones so every a by b rectangle with area K holds an odd number of stones, or report -1 if impossible.	Hard8	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
Merging CellsGiven N cells in a row with sizes, adjacent cells merge at random until one remains, and the task is to find the probability each original label ends as the winner modulo 1e9+7.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Walking in ManhattanGiven horizontal and vertical roads and cows that walk north or east at intersections by parity, find where each cow is after d seconds.	Hard8	SimulationBinary search+1	No attempts yet	2s	1024 MB	Judgeable
CowmpetencyCount the score sequences of N cows, each score from 1 to C, that satisfy each pair where cow h is the first with a score above cows 1 through a, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
VirusGiven a tree of points with spread times and people who each reach every point within distance D, find each person's infection time, starting from person 0 at time 0.	Hard8	TreeShortest path+2	No attempts yet	4s	1024 MB	Judgeable
Test Data CreationGiven the cost of setting each grid cell to 1, pick the cheapest cells so the grid makes Jinwoo's swapped N and M code print Yes, then print the grid.	Hard8	GraphMatrix	No attempts yet	4s	512 MB	Judgeable
Attraction ScoreChoose a subset of cities that maximizes the sum of highway attraction points inside the subset, minus 10^6 times the square of the number of non-adjacent city pairs.	Hard8	GraphBrute force	No attempts yet	4s	1024 MB	Judgeable
Tree QuizGiven a rooted tree, answer queries for the k-th smallest key among (x-1)nn + (LCA(x, y)-1)*n + (y-1) over all ordered pairs x, y.	Hard8	TreeDFS+1	No attempts yet	4s	1024 MB	Judgeable
Garden 2Given an N by N grid of R, Y, and B cells, find the largest diamond pattern where each concentric ring has one color and count its flowers.	Hard8	Dynamic programmingMatrix+1	No attempts yet	4s	1024 MB	Judgeable
Road Service 2Given a grid road network where each east-west row can be repaired for 1 or 2 days, find the minimum total repair period that connects each query's intersections.	Hard8	GraphUnion-find+1	No attempts yet	3s	1024 MB	Judgeable
Eggplant Field PathCount the distinct ways a monotone lattice path from (0,0) to (R,C) can split the planted branches into upper and lower sets without touching any branch.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
RightplantGiven N, build an arrangement of heights 1 to N so that the total number of direction reversals over all rightward branch fires is maximized.	Hard8	ArraySimulation+1	No attempts yet	1s	1024 MB	Judgeable
Eggplant Summoning MagicGiven N integer points in 3D, pick a structure-preserving map and M of the points that become a regular M-gon, maximizing N times M.	Hard8	GeometryMath+1	No attempts yet	4s	1024 MB	Judgeable
Infection SimulationGiven N customer stay intervals, each query asks how many customers end up infected from a given patient zero when the infection resistance is X.	Hard8	IntervalsGraph+2	No attempts yet	1.5s	1024 MB	Judgeable
Target Practice IIAssign each of the 4N cows on the y-axis to a distinct target vertex so no shot crosses a target interior, minimizing the largest distance between cows.	Hard8	GeometryBinary search+2	No attempts yet	2.5s	1024 MB	Judgeable
MoorblesGiven N marbles and M turns with K possible bets per turn, find the lexicographically smallest Even/Odd guess sequence that keeps Elsie from losing, or print -1.	Hard8	Dynamic programmingGame theory+1	No attempts yet	2s	1024 MB	Judgeable
Milk ExchangeGiven N buckets in a circle, each passing milk left or right every minute with capacity limits, find the total milk remaining after M minutes.	Hard8	SimulationPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Special Dropkick 2Given a corridor string with obstacles, push obstacles at most M times, then find the minimum seconds to walk from zone 0 to zone N, breaking obstacles for 2 seconds each.	Hard8	Dynamic programmingGreedy+1	No attempts yet	1s	1024 MB	Judgeable
BitoviGiven two sets A and B of N numbers below 2^15, output single-bit flips that turn A into B, where each target must not already be in A.	Hard8	GraphBFS+1	No attempts yet	1s	1024 MB	Judgeable
Pirate CodeFor each length k up to n, sum the decoded values of all binary codes of length k under Fibonacci pirate splitting, modulo 10^9+7.	Hard8	Dynamic programmingCombinatorics+1	No attempts yet	2s	1024 MB	Judgeable
So I'll Max Out My Constructive Algorithm SkillsGiven an n by n grid whose heights are a permutation of 1 to n^2, find a path visiting every cell once where climbs are at most descents.	Hard8	MatrixImplementation+1	No attempts yet	1s	1024 MB	Judgeable
Link-Cut TreeGiven an undirected graph where edge i has length 2^i, find the simple cycle with the smallest total length and print its edge indices, or -1 if no cycle exists.	Hard8	GraphUnion-find+1	No attempts yet	2s	1024 MB	Judgeable
Colourful TreeAfter each operation, find the largest distance between two vertices of different colours in a tree that grows by adding leaves and recolouring vertices.	Hard8	TreeDivide and conquer+1	No attempts yet	6s	1024 MB	Judgeable
Bajtocja Village ModernizationProcess deliveries that go to one of two residents, computer breakages, and queries, and report whether a given resident certainly has, certainly lacks, or may have a computer.	Hard8	Segment treeImplementation	No attempts yet	3s	1024 MB	Judgeable
CoinsCount the ways to add stacks of blue and red coins so that the whole row is a second-player win, for each total stack count from k to n.	Hard8	Game theoryCombinatorics+1	No attempts yet	25s	1024 MB	Judgeable
UDP StacksGiven a permutation, decide whether the three special stacks U, D, and P can be filled so that the elements, listed in the order they fell, come out in ascending order.	Hard8	StackGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Hyper Tree ProblemGiven a weighted tree, update edge weights with bitwise AND and report, for a query vertex, the sum over all vertices of the OR of edge weights on the path.	Hard8	Bit manipulationUnion-find+2	No attempts yet	4s	1024 MB	Judgeable
Fish 3For each range of fish, find the fewest type A foods needed to match the target intelligence values, or -1 if the targets cannot be reached.	Hard8	GreedyMath+1	No attempts yet	2s	1024 MB	Judgeable
Growing Vegetables is Fun 5Pair 2N seedlings with red and blue pots so one color fills a block of N consecutive positions, minimizing the largest size difference.	Hard8	Binary searchGreedy+1	No attempts yet	5s	1024 MB	Judgeable
Card CollectionGiven N cards with strength and cost, find which of M target cards can be built by repeatedly merging adjacent cards with componentwise max or min.	Hard8	Divide and conquerSegment tree+1	No attempts yet	4s	1024 MB	Judgeable
Escape Route 2Given daily repeating flight schedules between consecutive cities, find the minimum travel time from city L to city R for each query.	Hard8	Dynamic programmingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Island HoppingGiven N islands and at most L queries that return the k-th closest island to v, recover all N-1 sea routes of a hidden tree.	Hard8	TreeGraph+1	No attempts yet	2s	1024 MB	Judgeable
Love is WarGiven two sequences A and B of length N, sum over all subarrays the largest value that appears in both within that subarray.	Hard8	Segment treeArray+1	No attempts yet	2s	1024 MB	Judgeable
Fair DistributionGiven N buildings with ground height G and residential floor height R, decide whether they can be split between two children so each child's total height is equal.	Hard8	Dynamic programmingNumber theory+1	No attempts yet	1s	1024 MB	Judgeable
Splitting HaybalesGiven sorted haybales and queries (l, r, x), find Bessie minus Elsie after giving each bale in l to r to the cow with less hay.	Hard8	ArrayDivide and conquer+1	No attempts yet	2s	1024 MB	Judgeable
Activating RobotsGiven a circle of length L and activation points, find the minimum time for you and robots moving at speed 1/K to form R equally spaced robots.	Hard8	GreedyBinary search+2	No attempts yet	5s	1024 MB	Judgeable
The 'Winning' GeneFor each (K, L) pair, collect the start positions of the lexicographically smallest length-L substring in every length-K window, then count pairs by set size.	Hard8	StringString matching+1	No attempts yet	1s	1024 MB	Judgeable
The Phoenix That Topples the SchoolGiven bricks stacked on floors, find the most bricks that can fall after removing one brick, when unsupported bricks collapse floor by floor.	Hard8	Dynamic programmingStack+2	No attempts yet	2s	1024 MB	Judgeable
V.I.P.Count the paths over active edges whose vertex weights strictly increase, answering each edge-flip query modulo 10^9+7.	Hard8	GraphDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Discount EventGiven a weighted tree, for each query (X, Y) set every edge on the X to Y path to cost 0 and output the largest distance between any two cities.	Hard8	TreeDynamic programming+1	No attempts yet	4s	1024 MB	Judgeable
Virus SimulatorProcess virus spreads that pass between people, vaccinations, and range queries for the largest sum of a block of consecutive people with positive immunity.	Hard8	Segment treeSimulation	No attempts yet	3s	1024 MB	Judgeable
Yunny's TripFind the minimum stamina needed to walk from (0, 0) to (Ex, Ey) with unit moves (cost 1) and repeatable item vectors (cost 2), never dropping below 0.	Hard8	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
Hula's CardgameGiven tables whose three cards point to tables at or above their own number, decide for each E whether Geunsu can reach table E while Seunghyeong deletes one card per move.	Hard8	Game theoryGraph+1	No attempts yet	2s	512 MB	Judgeable
Carl's VacationFind the shortest walk between the apexes of two right square pyramids, moving only on their faces and the ground plane.	Hard8	GeometryShortest path+1	No attempts yet	1s	1024 MB	Judgeable
Three Kinds of DiceGiven two dice where the first beats the second, find a third die that ties or beats the first and report the lowest score it can get against the second, and the reverse bound.	Hard8	ProbabilitySorting+2	No attempts yet	1s	1024 MB	Judgeable
CompressionGiven a binary string, repeatedly remove one copy of any consecutive repeated substring and output the shortest string that can be reached.	Hard8	String matchingString+1	No attempts yet	1s	1024 MB	Judgeable
Fundamental MagicPick a rectangle anchored at (0, 0) that leaves out at least one color entirely, and maximize the total mana of the sources inside it.	Hard8	Segment treeSorting	No attempts yet	1s	1024 MB	Judgeable
PopcornGiven N popcorn types, each with an edible time window [A, B) and a quantity C, choose M cooking times to maximize the total edible popcorn.	Hard8	IntervalsGreedy+1	No attempts yet	2s	1024 MB	Judgeable
BfsBoys push the tilt right and girls push it left, in an order that keeps the tilt within S. After each swap inside one group, decide whether a valid order still exists.	Hard8	Dynamic programmingSegment tree+1	No attempts yet	1s	1024 MB	Judgeable
RevengeEach edge in an index range can be crossed for its cost or skipped for its rejection cost; find the minimum cost from u to v for each query range.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	1s	1024 MB	Judgeable
Strange Tree HashingGiven a target root hash h, output two non-isomorphic rooted trees whose root hash under H(K) = 2^(product of child hashes) equals h, or -1 if none exist.	Hard8	TreeMath+2	No attempts yet	1s	1024 MB	Judgeable
Farm Land SplitPick a rectangle and split it into two rectangles so no farm lies on a boundary, maximizing the total of both satisfaction sums.	Hard8	GeometrySegment tree+1	No attempts yet	5s	1024 MB	Judgeable
1D GameFind the earliest turn at which the character can reach cell L without standing on a temporary platform during a dangerous turn, where dangerous turns repeat every T turns.	Hard8	Shortest pathGraph+1	No attempts yet	2s	1024 MB	Judgeable
Champernowne SubstringFill each ? in the pattern with a digit to minimize the index where it first appears in the Champernowne string, printed mod 998244353.	Hard8	Dynamic programmingString+2	No attempts yet	10s	2048 MB	Judgeable
Square of TrianglesGiven the squared side lengths of four triangles, decide whether they can be rearranged without gaps or overlaps into a square.	Hard8	GeometryMath+1	No attempts yet	5s	2048 MB	Judgeable
Binary TreeFor each tree T_i built by joining two earlier trees, sum the fewest subtrees needed to cover each contiguous leaf range exactly.	Hard8	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
TilesGiven a simple axis-aligned polygon, find the largest k at most M such that the part left of x = k can be covered by non-overlapping 2 by 2 tiles.	Hard8	Dynamic programmingGeometry	No attempts yet	2s	1024 MB	Judgeable
MinequakeGiven a tree of n halls, start anywhere and visit every hall, minimizing the sum of the arrival times at each hall.	Hard8	TreeDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable