Problems

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Total results29,414 problems

Ladder Manipulation
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Catch the Plane
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Conquer the World
Hard8
Tree, DFS+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Gem Island
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Getting a Jump on Crime
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Go with the Flow
Hard8
Brute force, String+2
No attempts yet
Time limit
12s
Memory limit
1024 MB
Judgeable
Panda Preserve
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Single Cut of Failure
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Wireless Instead of Fiber
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
xor game
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Slingshot
Hard8
Divide and conquer, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Barns
Hard8
Tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow Gymnasts
Hard8
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Snow Boots
Hard8
Binary search, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Out of Sorts
Hard8
Sorting, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Disruption
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Out of Sorts
Hard8
Sorting, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Milking Order
Hard8
Graph, Topological sort+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multiplayer Moo
Hard8
DFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Duathlon
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Recipe
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Yut Nori
Hard8
Implementation, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Magic
Hard8
Hash map, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Particles
Hard8
Sorting, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Six
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Camel
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Experience
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
System Call
Hard8
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Namje Adventure
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Land of the Rainbow Gold
Hard8
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Travelling Businessmen Problem
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Non-Interactive Guessing Number
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Make a Forest
Hard8
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Parks of Jakarta
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Random Number Generator
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ANTS
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
XEN 3166
Hard8
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Permutation
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sacred Scarecrows
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Citations
Hard8
Tree, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Love Polygon
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Paths
Hard8
Graph, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Subway
Hard8
Graph, Tree+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
IP over Avian Carriers
Hard8
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Nordic Camping
Hard8
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mysterious Array
Hard8
Combinatorics, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pineapple Farming
Hard8
Union-find, BFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Pineapple Pizza
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Turf Wars
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Longest Common Palindromic Substring
Hard8
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Split and Merge
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Baby Seokhwan
Hard8
Sorting, Union-find+1
No attempts yet
Time limit
5s
Memory limit
768 MB
Judgeable
Full House
Hard8
Combinatorics, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Matrix Multiplication
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rooks
Hard8
Graph, Greedy+2
No attempts yet
Time limit
0.4s
Memory limit
1024 MB
Judgeable
A Simple Problem
Hard8
Number theory, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Prodo's 100-Day Preparation
Hard8
Array, Stack+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Catching Water Bottles
Hard8
Segment tree, Simulation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Harmonious Matrix
Hard8
Sorting, Hash map+2
No attempts yet
Time limit
5s
Memory limit
768 MB
Judgeable
Genealogy
Hard8
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Teleport Pads
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Magic Necklace
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Kakao Money
Hard8
Math, Number theory+2
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
Opening the Treasure Box
Hard8
Dynamic programming, String+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Magnet Toy
Hard8
Graph, Implementation+2
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Shootings
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
POPA
Hard8
Divide and conquer, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maximum Strategic Savings
Hard8
Minimum spanning tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Global warming
Hard8
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lottery
Hard8
String matching, Hash map+2
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Toys
Hard8
Number theory, Combinatorics+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Triangles
Hard8
Geometry, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Playoff by all the teams
Hard8
Brute force, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Equilateral Triangular Fence
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Cut It Out!
Hard8
Geometry, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flashing Fluorescents
Hard8
BFS, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rainbow Graph
Hard8
Greedy, Minimum spanning tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Winter Festival
Hard8
Graph, DFS+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Zoning Houses
Hard8
Segment tree, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Word Clock
Hard8
Backtracking, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Battle Royale
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hyper Illuminati
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Монгол ардын үлгэр
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cruise Quail
Hard8
Graph, Union-find+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Willy Feels Guilty
Hard8
String matching, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Amateur Radio Network
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Grumpy Groundhogs in Gridland
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fair Share
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Grievous Loss of Data
Hard8
Graph, Intervals+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Hiding Merlin
Hard8
String matching, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Injecting DNA
Hard8
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Judge's Mistake
Hard8
Greedy, Sorting+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Last Casino
Hard8
Math, Probability+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
I'm a Fan
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cherrypick
Hard8
Matrix, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Office Relocation
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Club Room Expansion
Hard8
Dynamic programming, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ttururu Tturu
Hard8
DFS, Brute force+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Number Theory and Applications
Hard8
Number theory, Math+2
No attempts yet
Time limit
0.2s
Memory limit
16 MB
Judgeable
Number Theory and Applications: Recitation
Hard8
Number theory, Math+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Ladder ManipulationGiven a ladder with N vertical lines, H rows, and M existing rungs, find the minimum number of rungs to add so every walk from column i ends at column i, or report -1 if more than 3.	Hard8	BacktrackingBrute force+2	No attempts yet	2s	512 MB	Judgeable
Catch the PlaneChoose an adaptive strategy of buses to maximize the probability of reaching station 1 by time k, where each bus runs independently with a known probability.	Hard8	Dynamic programmingProbability+2	No attempts yet	10s	1024 MB	Judgeable
Conquer the WorldArmies sit on the nodes of a weighted tree; move them along edges to satisfy each node's demand while minimizing total transport cost.	Hard8	TreeDFS+1	No attempts yet	8s	1024 MB	Judgeable
Gem IslandAt each of d steps a uniformly random gem splits in two; find the expected total held by the r largest holders after d splits.	Hard8	ProbabilityDynamic programming+2	No attempts yet	3s	1024 MB	Judgeable
Getting a Jump on CrimeGiven building heights on a grid, find the minimum number of jumps to reach each roof, where a jump is valid only if its parabola clears every building between the two roofs.	Hard8	GraphBFS+2	No attempts yet	2s	1024 MB	Judgeable
Go with the FlowChoose a line width for justified monospaced text, then find the longest run of spaces that drifts by at most one column per line, and report the best width and length.	Hard8	Brute forceString+2	No attempts yet	12s	1024 MB	Judgeable
Panda PreserveGiven a simple polygon and receivers at its vertices with a common radius, find the smallest radius whose union of disks covers the whole polygon.	Hard8	GeometryBinary search+2	No attempts yet	10s	1024 MB	Judgeable
Single Cut of FailureWires cross a rectangle between boundary sides; find the fewest straight cuts connecting different sides that cross every wire, and output the lexicographically smallest such cut.	Hard8	GeometrySorting+2	No attempts yet	6s	1024 MB	Judgeable
Wireless Instead of FiberGiven a connected multigraph, output a spanning tree minimizing the number of vertices whose degree differs from the original, following a prescribed construction procedure.	Hard8	GraphGreedy+2	No attempts yet	2s	1024 MB	Judgeable
xor gameCount sequences of n xor masks (each below 2^31) that carry a to b, modulo 1e9+7.	Hard8	MathCombinatorics+2	No attempts yet	0.5s	128 MB	Judgeable
SlingshotFor each of M queries (a, b), find the minimum time to move manure from a to b using the tractor (cost equals distance) plus at most one slingshot that flies from x to y in time t.	Hard8	Divide and conquerSorting+2	No attempts yet	2s	512 MB	Judgeable
New BarnsProcess online queries that add a leaf to a growing forest or ask for the eccentricity (distance to the farthest node) of a given node.	Hard8	TreeGraph+2	No attempts yet	2s	512 MB	Judgeable
Cow GymnastsCount circular stack-size assignments of length N (N up to 1e12) that stay unchanged after each stack falls clockwise, modulo 1e9+7.	Hard8	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Snow BootsFor each of B boots with limits on snow depth and step length, decide whether the farmer can walk from tile 1 to tile N, landing only on tiles whose snow is shallow enough.	Hard8	Binary searchSorting+2	No attempts yet	2s	512 MB	Judgeable
Out of SortsGiven an array, simulate a hybrid of quicksort and bubble sort that repeatedly bubbles until partition points appear, then splits, and report the total work counter.	Hard8	SortingSimulation+2	No attempts yet	2s	512 MB	Judgeable
DisruptionGiven a tree and extra weighted edges, for each tree edge report the minimum weight of a non-tree edge whose endpoints lie in different components after removing it.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Out of SortsGiven an array, count how many times the outer loop of a forward-backward bubble sort variant runs before the array becomes sorted.	Hard8	SortingMath+2	No attempts yet	2s	512 MB	Judgeable
Milking OrderFind the largest prefix of M ordered cow lists that stays acyclic, then output the lexicographically smallest topological order of that graph.	Hard8	GraphTopological sort+2	No attempts yet	2s	512 MB	Judgeable
Multiplayer MooGiven an N x N grid of cow IDs, find the largest connected region of one ID and the largest region formed by two IDs together.	Hard8	DFSGraph+2	No attempts yet	2s	512 MB	Judgeable
DuathlonCount ordered triples (s, c, f) of distinct vertices such that some simple path visits s, then c, then f, in an undirected graph with n up to 1e5.	Hard8	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
RecipeBuy ingredients on some days, hold each in the fridge until a later day, cook it there if freshness stays at least L_i, and maximize the total of F_i minus elapsed days times C_j; print Impossible if day N can't be a cooking day.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Yut NoriModel Yut Nori movement on four board routes and apply carrying, capturing and exit rules after each throw.	Hard8	ImplementationSimulation+1	No attempts yet	1s	1024 MB	Judgeable
MagicCount substrings of an N-character string in which all K distinct letters of the whole string appear an equal number of times, modulo 1e9+7.	Hard8	Hash mapPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
ParticlesGiven firing times and speeds of N particles from each of two facing accelerators, report the first K collisions between opposite kinds in chronological order.	Hard8	SortingTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
SixN has at most six distinct prime divisors; count the sequences of divisors greater than 1 where each new divisor shares a factor with at most one earlier entry, modulo 1e9+7.	Hard8	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
CamelConstruct a closed knight-like tour for a jumping camel piece on an N x N board where N is a multiple of 5, printing the visit order or NO.	Hard8	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
ExperienceGiven a rooted tree with values on nodes, partition nodes into vertex-disjoint downward paths to maximize the sum over paths of (max value minus min value).	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
System CallChoose one buffer size K for all files to minimize sum over files of ceil(F_i/K) times (T+K).	Hard8	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Namje AdventureN people hang at depths 1 to N and must reach the bottom depths D-N+1 to D; only the highest person can move down 1 to L steps, find the least total energy.	Hard8	Dynamic programmingGreedy+1	No attempts yet	3s	512 MB	Judgeable
Land of the Rainbow GoldGiven a grid where a serpent's path of river cells is carved by M moves, find the number of connected land components inside each of Q query rectangles.	Hard8	GraphUnion-find+1	No attempts yet	2s	512 MB	Judgeable
Travelling Businessmen ProblemGiven a connected undirected graph with mutable node values, answer queries asking the minimum possible difference between the values of two walkers' end cities.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Non-Interactive Guessing NumberGiven N, K, and Theodora's answer string, output guess values that follow the rules, or -1 if impossible.	Hard8	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
Make a ForestGiven N weighted tuples (u,v,w) with distinct weights, build a forest realizing each tuple as a parent-child edge so that every internal node's parent edge is smaller than all its child edges, each node has at most M children, and the number of trees is minimized. Output that minimum tree count.	Hard8	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Parks of JakartaGiven an initial stacking of N bricks over three parks plus up to 16 target configurations, find the cheapest move sequence visiting all targets and ending with all bricks in one park.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Random Number GeneratorGiven how many values from 1 to N have been seen zero or one time, find the expected number of draws until every value appears at least twice.	Hard8	ProbabilityDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
ANTSGiven a tree and a set of up to 50 marked nodes per query, find the node minimizing the sum of distances to all marked nodes, for up to 5000 queries.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
XEN 3166Assign each country a length-K subsequence starting with its first letter so that code order matches name lexicographic order, or report impossible.	Hard8	GreedyString+1	No attempts yet	2s	512 MB	Judgeable
PermutationGiven a permutation P and queries K, find the exponent T such that P^T is the K-th smallest among P^1 through P^(M-1) in lexicographic order.	Hard8	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Sacred ScarecrowsCount subsets of empty cells in an R x C grid, modulo 1e9+7, such that every row has a scarecrow and every pair of consecutive columns has one.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
CitationsOrder the reading of a citation tree rooted at book 1 so that the sum of all book return times is minimized.	Hard8	TreeGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Love PolygonEach of N people loves exactly one person; rewrite the minimum number of love targets so that everyone ends up in a mutual pair.	Hard8	GraphGreedy+2	No attempts yet	2s	1024 MB	Judgeable
PathsCount simple paths in a vertex-colored graph where every vertex on the path has a distinct color, counting both directions separately.	Hard8	GraphDFS+2	No attempts yet	3s	1024 MB	Judgeable
SubwayGiven two spanning trees on the same N stations, output a shortest sequence of weekend swaps, each removing one tree edge and adding another, so every intermediate graph stays a spanning tree and the target tree is reached.	Hard8	GraphTree+2	No attempts yet	2s	1024 MB	Judgeable
IP over Avian CarriersWrite an encoder that turns C×N bits into K strings of N bits, and a decoder that recovers the original bits from any C of those strings.	Hard8	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Nordic CampingGiven a grid with rocky cells blocked, answer queries each asking for the area of the largest all-usable square subgrid that contains a specified water source cell.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Mysterious ArrayCount permutations of 1..N consistent with Q range-minimum constraints, modulo 1e9+7, with contradictions giving 0.	Hard8	CombinatoricsSorting+2	No attempts yet	2s	512 MB	Judgeable
Pineapple FarmingOn a grid of heights with all outside cells treated as height 0, find the largest connected set of cells that forms a puddle bounded by strictly taller neighbors for some threshold h.	Hard8	Union-findBFS+2	No attempts yet	2s	256 MB	Judgeable
Pineapple PizzaGiven n points and a center Q, decide whether k rays from Q can split the plane so every sector holds exactly n/k points, with no point on a ray.	Hard8	GeometrySorting+2	No attempts yet	1s	256 MB	Judgeable
Turf WarsEach gang owns disjoint axis-aligned rectangles; pick exactly one rectangle to drop per gang so that no two kept rectangles from different gangs overlap, and report whether this is possible.	Hard8	GeometryBrute force+2	No attempts yet	2s	512 MB	Judgeable
Longest Common Palindromic SubstringGiven up to 50 strings with total length 1,000,000, find the length of the longest palindrome that occurs as a substring in every one of them.	Hard8	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Split and MergeGiven two tilings of a 1xL board by 1x1 and 1x2 pieces, find the minimum number of split/merge operations to transform one into the other and count the ways.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
Baby SeokhwanEach cell takes the value from the first query that writes it, and the task is to print the stable lexicographically smallest order that sorts the N vectors.	Hard8	SortingUnion-find+1	No attempts yet	5s	768 MB	Judgeable
Full HouseKnowing only how many cards were removed from a 52-card deck, find the minimum and maximum number of disjoint full houses (3 of one rank plus 2 of another) that can be formed from the remaining cards.	Hard8	CombinatoricsGreedy+2	No attempts yet	2s	512 MB	Judgeable
Matrix MultiplicationFor each prefix of n matrices, decide whether some multiplication order is valid, and if so report the largest possible area of the final product.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
RooksPlace the maximum number of non-attacking rooks on an N by N board where obstacles block lines of sight along ranks and files, and output one optimal placement.	Hard8	GraphGreedy+2	No attempts yet	0.4s	1024 MB	Judgeable
A Simple ProblemFind positive integers B_i so that the product of (A_i + B_i)/B_i equals 1 + (2^m - 1)/n, or report that none exist.	Hard8	Number theoryMath+2	No attempts yet	1s	512 MB	Judgeable
Prodo's 100-Day PreparationGiven a histogram-shaped rectilinear polygon by its vertices, find the largest-area L-shaped rectilinear polygon that can be cut from it.	Hard8	ArrayStack+1	No attempts yet	2s	512 MB	Judgeable
Catching Water BottlesGiven N bottles with thresholds D_i, count how many bottles plus Jaehyeok lie within [L, R] at time T as the bottles trail him each second.	Hard8	Segment treeSimulation+1	No attempts yet	2s	256 MB	Judgeable
Harmonious MatrixGiven a 2xN or 3xN matrix of distinct integers, find the largest subset of columns whose orderings within each row are identical, and report its column count.	Hard8	SortingHash map+2	No attempts yet	5s	768 MB	Judgeable
GenealogyDecide whether two queen family trees with the same childless names can both be produced by merging parent-child pairs from one original tree.	Hard8	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
Teleport PadsEach pad cycles through a fixed list of zones with its own period; find the earliest time Hyeonuk, starting on pad 1 at coordinate 0, can reach the exit zone by riding and switching pads.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Magic NecklaceFor each of the N cut positions on a circular array, fuse contiguous segments into one bead equal to their gcd so that every resulting bead is 1, and report the maximum bead count.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Kakao MoneyGiven a log of deposits and withdrawals with resulting balances, find a minimum charge unit M that is consistent with every withdrawal, or report that none exists.	Hard8	MathNumber theory+2	No attempts yet	5s	256 MB	Judgeable
Opening the Treasure BoxFor each start position, find the minimum replacement cost plus walking cost (c per step) to make the letter string a palindrome.	Hard8	Dynamic programmingString+1	No attempts yet	1s	256 MB	Judgeable
Magnet ToyGiven a simple graph, decide whether its vertices can be removed one by one so that each removed vertex's remaining neighbors form a clique, and output the order if possible.	Hard8	GraphImplementation+2	No attempts yet	1.5s	256 MB	Judgeable
ShootingsGiven non-overlapping axis-aligned rectangles and shots that are vertical or 45-degree half-lines, compute for each shot the squared total length of its intersection with all rectangles.	Hard8	GeometrySorting+2	No attempts yet	1s	512 MB	Judgeable
POPABuild a binary tree on indices with inorder order 0..N-1 and parent weights dividing child weights, using at most Q gcd-equality queries on hidden subarrays.	Hard8	Divide and conquerTree+2	No attempts yet	1s	512 MB	Judgeable
Maximum Strategic SavingsGiven N planets each with M cities and edge sets shared across copies, find the maximum energy saved by keeping a spanning connected subgraph of the whole galaxy.	Hard8	Minimum spanning treeGraph+2	No attempts yet	2s	512 MB	Judgeable
Global warmingChoose one contiguous interval and a shift d with \|d\| <= x, then find the maximum possible length of a strictly increasing subsequence of the modified sequence.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
LotteryFor each of n-l+1 length-l windows and each query threshold k, count how many other windows differ from it in at most k positions.	Hard8	String matchingHash map+2	No attempts yet	2s	32 MB	Judgeable
ToysFor a given n, find every total toy count m whose partitions into type-quantities number exactly n.	Hard8	Number theoryCombinatorics+2	No attempts yet	4s	512 MB	Judgeable
TrianglesFind the number of vertices of the convex hull of n points using only clockwise or counterclockwise orientation queries on triples, with a query budget.	Hard8	GeometryDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Playoff by all the teamsCount the ways to fill in the unplayed matches of a round-robin tournament so that every team ends with the same number of wins.	Hard8	Brute forceBacktracking+2	No attempts yet	2s	512 MB	Judgeable
Equilateral Triangular FenceGiven pear trees above a road, find the shortest perimeter of an equilateral triangle with a horizontal base that encloses all but at most k trees.	Hard8	GeometryBinary search+1	No attempts yet	8s	512 MB	Judgeable
Cut It Out!Given convex polygons A and B with B strictly inside A, find the minimum total length of cuts along B's edge lines that leave exactly B.	Hard8	GeometryDynamic programming	No attempts yet	2s	512 MB	Judgeable
Flashing FluorescentsGiven up to 16 initial light states, find the earliest time at which all lights can be simultaneously on, where each button press sends a delayed toggle wave down the line and overlapping waves cancel.	Hard8	BFSBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Rainbow GraphFor each k from 1 to m, find the minimum total weight of k edges that connect all nodes using only Blue and Green edges and also using only Red and Green edges.	Hard8	GreedyMinimum spanning tree+1	No attempts yet	2s	512 MB	Judgeable
Winter FestivalAssign costs 0, 1, or 2 to each road so that no area has adjacent roads whose costs sum to 1 mod 3 and every cycle has an odd sum; find the minimum total.	Hard8	GraphDFS+1	No attempts yet	5s	512 MB	Judgeable
Zoning HousesFor each query range of houses, find the side length of the smallest axis-aligned square covering all points in the range, with the option to drop one point.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Word ClockPlace n distinct words left to right on an h by w grid where words may share letters, or report that no placement exists.	Hard8	BacktrackingImplementation+2	No attempts yet	2s	512 MB	Judgeable
Battle RoyaleFind the shortest path between two points inside a circle while staying outside an inner red circle, touching boundaries only.	Hard8	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Hyper IlluminatiGiven m up to 10^16, find n >= 3 and s >= 1 such that the block count of an n-dimensional hyper-step pyramid with s steps equals m, or report impossible.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
Монгол ардын үлгэрChoose a subset whose size is at most the total weight of the remaining stones, maximizing the value of that chosen subset.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
Cruise QuailFind the cheapest edge subset hitting every pair of edge-disjoint simple paths, equivalently place cameras inside each 2-edge-connected block.	Hard8	GraphUnion-find+2	No attempts yet	3s	512 MB	Judgeable
Willy Feels GuiltyBuy, throw, or swap products so the delivered sequence realizes a fixed menu at minimum total cost.	Hard8	String matchingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Amateur Radio NetworkSplit at least 4 points into two groups of size at least 2 minimizing the largest same-group pairwise distance, and output that diameter rounded up to 0.01.	Hard8	GeometryBinary search+2	No attempts yet	2s	512 MB	Judgeable
Grumpy Groundhogs in GridlandGiven N nested or disjoint burrow pairs on a line at depth 0, find the minimum maximum digging depth connecting only matched pairs, or report IMPOSSIBLE.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Fair ShareGiven n weighted points around the origin, choose a line through the origin that splits them into two half-planes, minimizing the absolute difference of the two half-plane weight sums.	Hard8	GeometrySorting+2	No attempts yet	5s	512 MB	Judgeable
Grievous Loss of DataGiven the clash graph of N interval lectures, find the minimum number of halls, which equals the chromatic number guaranteed realizable by intervals.	Hard8	GraphIntervals+2	No attempts yet	6s	512 MB	Judgeable
Hiding MerlinDecompose a digit string into concatenated perfect squares, each at most 10 digits and starting with 1 to 9, and report the smallest possible total sum.	Hard8	String matchingDynamic programming+2	No attempts yet	4s	512 MB	Judgeable
Injecting DNAFor every suffix of a string, compute its toxicity from the number of out-of-order suffix pairs, then output the length of the suffix with the largest effectiveness.	Hard8	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
Judge's MistakeGroup sorted road triples to maximize disjoint pairs of equal (w, endpoint multiset) triples for the cheapest surviving-road sum.	Hard8	GreedySorting+1	No attempts yet	4s	512 MB	Judgeable
Last CasinoGiven n bins, pick a ball count from 1 to 10^6 and a red, black, or white coloring that makes Alice's and Britney's win probabilities as close as possible.	Hard8	MathProbability+1	No attempts yet	2s	512 MB	Judgeable
I'm a FanFind the smallest CCW rotation angle whose swept orbit of a star-shaped polygon around the origin is a full disk.	Hard8	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
CherrypickFor each cell, find the axis-aligned square containing it that maximizes the minimum cherry sweetness minus the square of its side length.	Hard8	MatrixBinary search+2	No attempts yet	2s	512 MB	Judgeable
Office RelocationGiven a weighted tree with marked query and leaf-coloured vertices, compute for every marked vertex the sum of squared weighted distances to coloured leaves (mod a prime).	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Club Room ExpansionGiven each cell's count of walled directions (0 to 4), decide whether the grid can be fully partitioned into connected rooms of one to three cells fitting that wall count.	Hard8	Dynamic programmingBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Ttururu TturuCount self-avoiding walks of length 10 on an R x C grid whose cell contents read exactly "ttururu tturu" (the 5-letter chorus "뚜루루뚜루" written row-wise twice).	Hard8	DFSBrute force+2	No attempts yet	0.5s	512 MB	Judgeable
Number Theory and ApplicationsGiven two Gaussian integers up to 10^9 in each coordinate, output every greatest common divisor in lexicographic order.	Hard8	Number theoryMath+2	No attempts yet	0.2s	16 MB	Judgeable
Number Theory and Applications: RecitationGiven n up to 1e9 and v up to 100, compute the sum over i=1..n and u=1..v of Jordan's totient function modulo 1e9+7.	Hard8	Number theoryMath+2	No attempts yet	4s	512 MB	Judgeable