Problems

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Total results29,416 problems

Special Ability 2
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fewest letters for a suffix array
Hard8
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Donghyuk's Walk
Hard8
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Picking Out Numbers
Hard8
Bit manipulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minho's Wish
Hard8
Segment tree, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hongjun and the Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Easily Happy Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Polygon Game
Hard8
Game theory, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Barbarians
Hard8
Tree, Union-find+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Containers and Reagents
Hard8
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Elimination Round, Problem F
Hard8
Number theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chaos
Hard8
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Adventure of Marty and Doc
Hard8
Math, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alternative Bracket Notation
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Programming Team
Hard8
Dynamic programming, Tree+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Symmetry
Hard8
Geometry, Hash map+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Jewel Thief
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Tourists
Hard8
Tree, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Whiteboard
Hard8
Simulation, Implementation+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Billboard
Hard8
Sliding window, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fence
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Modern Announce Network
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Cube Dividing
Hard8
Graph, BFS+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Shortest Bridge
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Longest Shortest Path
Hard8
Shortest path, Binary search+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Optimal Tournament
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Unknown Switches
Hard8
Bit manipulation, Math+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Square in Circles
Hard8
Geometry, Binary search
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Color the Map Extreme
Hard8
Geometry, Graph+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Website Tour
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Binary Search Game
Hard8
Binary search, Greedy+1
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
Calculation mistake
Hard8
Segment tree, String+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Scorpion Test for Permutation Graphs
Hard8
Graph, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Checkpoint candidates
Hard8
Graph, DFS
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Counting Bow Ties
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Gambling and rectangles
Hard8
Combinatorics, Math+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Counting Functions
Hard8
Combinatorics, Graph+1
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Baseball Watching
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ignition
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
King of Chairs
Hard8
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
32 MB
Judgeable
Fallen Crystals
Hard8
Binary search, Game theory+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Coins
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Woodworking
Hard8
Dynamic programming, Probability+1
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
K-minsum of Permutations
Hard8
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Handshakes
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Black and White
Hard8
Combinatorics, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Popeala
Hard8
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Router 2
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Router 7
Hard8
Graph, Tree+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Seunghyun and Seunghyun
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Quarantine Stations
Hard8
Tree, Binary search+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Counting rectangles by distinct numbers
Hard8
Implementation, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Casino
Hard8
Dynamic programming, Probability+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Beauty of the sequence
Hard8
Dynamic programming, Probability
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jailbreak
Hard8
Dynamic programming, Divide and conquer+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cookie Tray
Hard8
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
The Spy
Hard8
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Password
Hard8
String, Sorting+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Big Number Multiplication
Hard8
Math, String+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Fibonacci Numbers of Subset Sums
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Warp Drive
Hard8
Geometry, Brute force+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Gift Exchange Party
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dots and Boxes
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Free Desserts
Hard8
Bit manipulation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Primonimo
Hard8
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tree
Hard8
Tree, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fake Prime
Hard8
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Building an Increasing Sequence
Hard8
Greedy, Math
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minimum Diameter Sum
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Meteor Shower
Hard8
Geometry, Sorting+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pseudo Palindrome
Hard8
Dynamic programming, String matching+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cartesian Tree
Hard8
Dynamic programming, Tree+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
XOR Sequence
Hard8
Divide and conquer, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Magic Towers and Teleportation
Hard8
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two Trees
Hard8
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Landlord
Hard8
Shortest path, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rock Band
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Artwork
Hard8
Union-find, Implementation+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Exponial
Hard8
Number theory, Recursion+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Longest Welded Sword
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Interception
Hard8
Graph, Greedy+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Keeping the Dogs Apart
Hard8
Geometry, Two pointers+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Weeping Fig
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Counting Similar Trees
Hard8
Tree, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Special Tables
Hard8
Combinatorics, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Palindrome Matrix
Hard8
Bit manipulation, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cartesian Tree 2
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Placing Medals on a Binary Tree
Hard8
Greedy, Tree+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Cover the Polygon with Your Disk
Hard8
Geometry, Binary search+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Black and White Boxes
Hard8
Game theory, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sorting Game
Hard8
Sorting, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Inversions of a simple path sequence
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Laser Towers
Hard8
Greedy, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Blue vertex distance sums on a tree
Hard8
Tree, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Good Substrings
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Number of Regions
Hard8
Combinatorics, Geometry+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Segments in a Regular Polygon
Hard8
Backtracking, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Counting ear shapes
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Store Name
Hard8
String, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Special Ability 2Given a weighted directed graph, find the minimum cost path from vertex 1 to N where each edge traversal may be negated, using at most C negations.	Hard8	GraphShortest path+1	No attempts yet	2s	512 MB	Judgeable
Fewest letters for a suffix arrayGiven a permutation that is a suffix array, find the minimum number of distinct letters needed for a string that realizes exactly this suffix array.	Hard8	StringGreedy+2	No attempts yet	2s	512 MB	Judgeable
Donghyuk's WalkWith at most 47 blocked cells on an infinite grid, find the largest x coordinate reachable from the origin in exactly K seconds, where waiting is allowed.	Hard8	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Picking Out NumbersChoose between 1 and k distinct integers from [l, r] minimizing the XOR of the chosen set, and output that minimum XOR.	Hard8	Bit manipulationMath+2	No attempts yet	2s	512 MB	Judgeable
Minho's WishFor each of Q range queries on an array, count how many distinct values occur at least three times within the queried index range.	Hard8	Segment treePrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Hongjun and the TreeProcess subtree updates that add a distance-dependent value to each vertex, answering point-weight queries modulo 1e9+7.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Easily Happy TreeDelete the fewest leaves from a rooted tree so that no remaining vertex has a descendant farther away than that descendant's own limit a_u.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Polygon GameTwo players alternately draw chords inside a convex N-gon that avoid all earlier chords, including shared endpoints; decide the winner under optimal play.	Hard8	Game theoryCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
TreeMaintain a rooted tree under vertex deletions (children reparent to grandparent) and answer distance queries between two live vertices.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
BarbariansA tree's edges are deleted one by one, each deletion multiplies each vertex's anger by (reachable before) - (reachable after) + 1, and after each deletion the total anger is printed modulo 1e9+7.	Hard8	TreeUnion-find+2	No attempts yet	4s	512 MB	Judgeable
Containers and ReagentsDecide whether all reagents can be fully distributed among containers so each container's volume range and one reagent's minimum percentage are met.	Hard8	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Elimination Round, Problem FGiven positive a_i and d, decide whether nonzero x_i exist with sum a_i x_i = d, and if so build the unique sequence defined by the greedy rule minimizing each \|D_i\|.	Hard8	Number theoryGreedy+2	No attempts yet	2s	512 MB	Judgeable
ChaosStarting from n numbers, repeatedly replace three numbers a, b, c by two copies of floor((sum of a chosen pair)/2); find the maximum equal value that can remain.	Hard8	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
New Adventure of Marty and DocPlace a recycling plant on one grid cell so a robot carries every part to it with the fewest moves, picking up and dropping one part at a time.	Hard8	MathPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Alternative Bracket NotationConvert a balanced bracket string into the shortest alternative notation, where each pair's header gives absolute start and end indices of its contents.	Hard8	Dynamic programmingTree+2	No attempts yet	10s	512 MB	Judgeable
Programming TeamChoose exactly k candidates from a tree where each pick needs its recommender picked, maximizing total productivity divided by total salary; print the ratio to three decimals.	Hard8	Dynamic programmingTree+2	No attempts yet	3s	512 MB	Judgeable
SymmetryGiven up to 1000 distinct lattice points, find the minimum number of extra points needed to make the set symmetric about some point or some line.	Hard8	GeometryHash map+2	No attempts yet	5s	512 MB	Judgeable
Jewel ThiefFor each knapsack capacity 1 through k, compute the maximum total value of a subset of n jewels whose sizes sum to at most the capacity.	Hard8	Dynamic programmingGreedy+1	No attempts yet	10s	512 MB	Judgeable
TouristsGiven a tree on n nodes, sum the number of nodes on the path from x to y over all pairs where y is a larger multiple of x.	Hard8	TreeMath+2	No attempts yet	5s	512 MB	Judgeable
WhiteboardGiven a path on a grid and a target pattern, find the smallest and largest drying timestep T so the final board matches the target.	Hard8	SimulationImplementation+2	No attempts yet	5s	512 MB	Judgeable
BillboardGiven a 0/1 matrix, find the largest all-1 sub-rectangle after flipping at most s zeros and clearing at most r rows entirely.	Hard8	Sliding windowTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
FenceGiven points on grid corners, find the shortest closed fence along cell edges and diagonals that encloses all of them, output as a + b*sqrt(2).	Hard8	GeometrySorting+1	No attempts yet	2s	512 MB	Judgeable
Modern Announce NetworkThree grade groups each broadcast internally for free; pick a start student so the friend-link forest spanning all three groups uses the fewest edges.	Hard8	GraphMinimum spanning tree+2	No attempts yet	5s	512 MB	Judgeable
Cube DividingCount the face-connected components of unit cubes left in an A x B x C box after removing N given cubes, where the box is huge but N is at most 20000.	Hard8	GraphBFS+2	No attempts yet	5s	512 MB	Judgeable
Shortest BridgeGiven two polygonal riverbanks and points s and t on opposite sides, minimize the bridge length between the banks, then the road lengths from s and t to its endpoints.	Hard8	GeometryBrute force+2	No attempts yet	5s	512 MB	Judgeable
Longest Shortest PathGiven a directed graph with edge lengths and per-unit lengthening prices, spend at most budget P to make the shortest s-t path as long as possible.	Hard8	Shortest pathBinary search+1	No attempts yet	10s	512 MB	Judgeable
Optimal TournamentPlace N contestants with given strengths at the leaves of a knockout bracket of height at most K so that the total strength difference over all matches is minimized.	Hard8	Dynamic programmingSorting+2	No attempts yet	5s	512 MB	Judgeable
Unknown SwitchesGiven switch-operation patterns and resulting bulb states over Q steps, determine which of N switches controls each bulb, or mark it unknown. Standard whiteboard task? No.	Hard8	Bit manipulationMath+2	No attempts yet	8s	512 MB	Judgeable
Square in CirclesGiven overlapping circles centered on the x-axis, find the side length of the largest axis-aligned square that fits inside their union.	Hard8	GeometryBinary search	No attempts yet	8s	512 MB	Judgeable
Color the Map ExtremeGiven simple polygons for each country, decide adjacency when borders share a positive-length segment, then find the chromatic number of the adjacency graph.	Hard8	GeometryGraph+1	No attempts yet	8s	512 MB	Judgeable
Website TourWalk a directed graph of N websites, watching ads (points p, time t, at most k times each) to maximize points within T seconds.	Hard8	GraphDynamic programming+2	No attempts yet	8s	512 MB	Judgeable
Binary Search GameDetermine whether a player can always guess x within a_x comparison questions given a monotone budget array, and list all valid first questions q.	Hard8	Binary searchGreedy+1	No attempts yet	2s	64 MB	Judgeable
Calculation mistakeMaintain a string of digits and plus or minus signs under range replacements, and evaluate the arithmetic value of any substring with the calculator's operator rules.	Hard8	Segment treeString+1	No attempts yet	3s	256 MB	Judgeable
Scorpion Test for Permutation GraphsAfter each swap in a permutation A, decide whether the permutation graph (edges between crossing chords) is scorpion-like.	Hard8	GraphSorting+2	No attempts yet	1s	256 MB	Judgeable
Checkpoint candidatesGiven an undirected graph, a set of source vertices, and a set of airport vertices, count the vertices that every source-to-airport path must pass through.	Hard8	GraphDFS	No attempts yet	2s	128 MB	Judgeable
Counting Bow TiesCount 4-cycles in a bipartite graph defined by M rectangles over vertex ranges, with N up to 1e9.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
Gambling and rectanglesCompute the expected score over all equally likely rectangles, where the score squares the count of each value 1 to 5, and print it as a reduced fraction.	Hard8	CombinatoricsMath+1	No attempts yet	1s	256 MB	Judgeable
Counting FunctionsCount functions f on {1..N} such that each i returns to itself after exactly A_i iterations, for N up to 16.	Hard8	CombinatoricsGraph+1	No attempts yet	1s	32 MB	Judgeable
Baseball WatchingEach of N students sits in one of three sections for nine innings; find the min and max number of students a moving teacher can avoid catching.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	1s	256 MB	Judgeable
IgnitionGiven a connected undirected weighted graph, choose a vertex to light so that the fire spreading along edges burns every point in the shortest total time.	Hard8	GraphShortest path+2	No attempts yet	1s	64 MB	Judgeable
King of ChairsArrange N ladies, each sitting or standing with probability 1/2, to maximize the expected number of ordered pairs where the person behind is strictly taller.	Hard8	SortingGreedy+2	No attempts yet	1s	32 MB	Judgeable
Fallen CrystalsGiven N crystals with distinct strengths and a hidden target at rank K, minimize the worst-case number of swings to break it using forces up to P without risking an explosion (force gap W).	Hard8	Binary searchGame theory+1	No attempts yet	1s	512 MB	Judgeable
CoinsCount how many of the 2^N head/tail coin layouts are wins for the second player under optimal play in this flipping game.	Hard8	Game theoryDynamic programming+1	No attempts yet	1s	512 MB	Judgeable
WoodworkingGiven plank recovery probabilities for a box needing N planks, compute the expected number of boxes built starting with M planks.	Hard8	Dynamic programmingProbability+1	No attempts yet	7s	512 MB	Judgeable
K-minsum of PermutationsSum the K-minsum over all N! permutations, where K-minsum adds the minimum of every contiguous block of length at least K+1.	Hard8	CombinatoricsMath	No attempts yet	2s	512 MB	Judgeable
HandshakesCompute the expected number of random handshakes until all N people belong to one acquaintance component, and output it modulo 1e9+7.	Hard8	ProbabilityDynamic programming+2	No attempts yet	4s	512 MB	Judgeable
Black and WhiteEach cell is black or white with probability 1/2; find the expected product of the number of all-black subrectangles and all-white subrectangles.	Hard8	CombinatoricsProbability+2	No attempts yet	2s	512 MB	Judgeable
PopealaPartition T weighted test cases into exactly K consecutive subtasks to minimize total scored points, for each K up to S.	Hard8	Dynamic programmingPrefix sum+1	No attempts yet	2s	512 MB	Judgeable
Router 2Build a unique-path layered router digraph with N inputs and N outputs, at most M_lim edges, node power at most P_lim, printing the lexicographically smallest edge list.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Router 7Build a router graph with N inputs, N outputs, and internal nodes so each input reaches each output by a unique path within edge and power limits.	Hard8	GraphTree+1	No attempts yet	2s	512 MB	Judgeable
Seunghyun and SeunghyunFor each query (S, E), find the minimum possible maximum value of C[a]*C[b] over calls made while the two travelers swap cities.	Hard8	GraphShortest path+1	No attempts yet	2s	256 MB	Judgeable
Quarantine StationsPlace K quarantine barriers on the edges of a weighted tree so that the largest connected component's total population is minimized.	Hard8	TreeBinary search+1	No attempts yet	3s	256 MB	Judgeable
Counting rectangles by distinct numbersCount rectangles of every size by how many distinct numbers they contain, then output a product of those counts modulo 1e9+7.	Hard8	ImplementationBit manipulation+2	No attempts yet	3s	256 MB	Judgeable
CasinoWith N players, M areas, and K rounds of random elimination, find the best survival probability for the group.	Hard8	Dynamic programmingProbability+1	No attempts yet	2s	512 MB	Judgeable
Beauty of the sequenceGiven N trees with independent uniform height ranges, find the expected maximum beauty of a zigzag subsequence.	Hard8	Dynamic programmingProbability	No attempts yet	2s	512 MB	Judgeable
JailbreakPartition L cells into at most G consecutive blocks, minimizing the sum over each cell of its escape power times its block length.	Hard8	Dynamic programmingDivide and conquer+1	No attempts yet	2s	512 MB	Judgeable
Cookie TrayCount tilings of an N by 5 grid with 2x1 dominoes, given K fixed 1x1 cells, modulo 1e9+7, with N up to 1e18.	Hard8	Dynamic programmingMatrix+1	No attempts yet	2s	256 MB	Judgeable
The SpyGiven difference constraints on N product scores in 0 to 100, find the smallest possible gap between the highest and lowest score, or -1 if no assignment exists.	Hard8	Shortest pathGraph+2	No attempts yet	1s	256 MB	Judgeable
PasswordGiven a length-N string, collect all distinct substrings meeting four counts (length, digits, specials, uppercase), sort them lexicographically, and print the middle one.	Hard8	StringSorting+2	No attempts yet	4s	512 MB	Judgeable
Big Number MultiplicationMultiply two non-negative integers of up to 300,000 digits each and print the exact product without leading zeros.	Hard8	MathString+1	No attempts yet	3s	512 MB	Judgeable
Fibonacci Numbers of Subset SumsSum F[sum(s)] over all K-element subsets s of a set of N distinct numbers, modulo 99991.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Warp DrivePlace two warp points on the plane to minimize the root mean square of flight times, where each time is min(direct, dist to nearest warp) divided by speed.	Hard8	GeometryBrute force+1	No attempts yet	8s	512 MB	Judgeable
Gift Exchange PartyOrient every edge of an undirected graph so that the max out-degree minus min out-degree is minimized, then among such orientations maximize the min out-degree. Output those two values.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Dots and BoxesGiven a Dots and Boxes position with no completed square, find the longest sequence of moves that still avoids closing any square, then print that length plus one.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Free DessertsCount pairs a, b with a < b, a + b = P, and no decimal digit repeats across a, b, and P, listing up to 5000 of them.	Hard8	Bit manipulationBrute force+2	No attempts yet	2s	512 MB	Judgeable
PrimonimoFind counts of row/column increments mod prime p that turn all squares into p, choosing the lexicographically smallest solution.	Hard8	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
TreeAfter each query asks whether two vertices are still connected, the tree may lose one edge based on the answer, so connectivity must be tracked under online deletions.	Hard8	TreeUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Fake PrimeFind the smallest composite n > L that passes the Fermat test for every base 2..500, and print its smallest prime factor.	Hard8	Number theoryMath+1	No attempts yet	2s	512 MB	Judgeable
Building an Increasing SequenceFind a strictly increasing integer sequence B minimizing the total absolute difference from a given sequence A.	Hard8	GreedyMath	No attempts yet	2s	512 MB	Judgeable
Minimum Diameter SumSplit a set of n planar points into two nonempty groups so that the sum of the two group diameters is minimized, and print the value.	Hard8	GeometryBinary search+2	No attempts yet	1s	512 MB	Judgeable
Meteor ShowerCount the convex polygons that are completely hidden from the origin by other polygons, since every ray stops at the first one it hits.	Hard8	GeometrySorting+1	No attempts yet	1s	512 MB	Judgeable
Pseudo PalindromeGiven a string w and a rational theta, split w into the fewest substrings that are each a theta-palindrome (form uvu^R with enough border), or report 0.	Hard8	Dynamic programmingString matching+1	No attempts yet	2s	512 MB	Judgeable
Cartesian TreeCount permutations of 1..N whose Cartesian tree has total child-position gap score at most S, modulo a prime.	Hard8	Dynamic programmingTree+1	No attempts yet	5s	512 MB	Judgeable
XOR SequenceChoose B in [0, N-1] to XOR every element of A, then find the maximum possible count of index pairs i < j with C_i < C_j.	Hard8	Divide and conquerBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Magic Towers and TeleportationDecide whether repeatedly reflecting the whole set of points across three fixed towers can turn one given point multiset into another, with soldiers considered indistinguishable.	Hard8	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Two TreesPick a vertex subset connected in both of two trees to maximize the total score, with the empty set allowed.	Hard8	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
LandlordFind the minimum travel time to visit a fixed sequence of districts, starting at 0, when cars parked in some districts can be used once each for faster driving.	Hard8	Shortest pathDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Rock BandEach of M members ranks all S songs; a set list is valid if every member plays all songs they rank above any chosen song. Find a shortest valid set list.	Hard8	GreedySorting+2	No attempts yet	4s	512 MB	Judgeable
ArtworkPaint horizontal and vertical black strokes on a grid one at a time, and after each stroke report the number of white connected regions.	Hard8	Union-findImplementation+2	No attempts yet	4s	512 MB	Judgeable
ExponialCompute n^(n-1)^(...^1) modulo m for n and m up to 1e9, a tower too tall to build.	Hard8	Number theoryRecursion+1	No attempts yet	2s	512 MB	Judgeable
The Longest Welded SwordSelect and order all plates so that widths strictly decrease, orienting each plate to maximize the total contributed length sum.	Hard8	GreedySorting+2	No attempts yet	7s	512 MB	Judgeable
InterceptionPlace the fewest listening devices on the edges of a street-wide phone-line graph so that every given call route is covered.	Hard8	GraphGreedy+2	No attempts yet	8s	512 MB	Judgeable
Keeping the Dogs ApartTwo dogs follow their own polyline routes at the same constant speed; find the minimum distance between them while both are still walking.	Hard8	GeometryTwo pointers+2	No attempts yet	6s	512 MB	Judgeable
Weeping FigSplit the vertices of a connected weighted undirected graph into two nonempty parts so that the total weight of edges crossing the cut is minimized.	Hard8	GraphMinimum spanning tree+2	No attempts yet	3s	512 MB	Judgeable
Counting Similar TreesGroup labeled trees that are isomorphic under a bijection preserving edge label differences, and report each group size.	Hard8	TreeHash map+2	No attempts yet	2s	512 MB	Judgeable
Special TablesCount the number of N by M tables with entries from 1 to C in which all rows are distinct and all columns are distinct, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming	No attempts yet	2s	512 MB	Judgeable
Palindrome MatrixFlip the fewest bits in an even-by-even 0/1 matrix so that at least R rows and at least C columns read as palindromes.	Hard8	Bit manipulationBrute force+1	No attempts yet	2s	512 MB	Judgeable
Cartesian Tree 2Sum the scores of the Cartesian trees of all N! permutations of 1..N, where a node's score is the index gap between its two children, modulo a prime.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Placing Medals on a Binary TreeGiven medals with depths in a pile, decide greedily and incrementally which can be placed on a perfect binary tree so that no placed node is an ancestor of another.	Hard8	GreedyTree+1	No attempts yet	4s	512 MB	Judgeable
Cover the Polygon with Your DiskPlace a fixed-radius disk anywhere on the plane to maximize the area shared with a convex polygon, and print that maximum.	Hard8	GeometryBinary search+1	No attempts yet	3s	512 MB	Judgeable
Black and White BoxesGiven up to 40 piles of black and white boxes, pick a subset so the first-player draw decides the winner and maximize total boxes.	Hard8	Game theoryDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Sorting GameApply K sets of operations, each sorting a prefix of length A ascending then a prefix of length B descending, and print the final sequence.	Hard8	SortingImplementation+2	No attempts yet	1s	128 MB	Judgeable
Inversions of a simple path sequenceGiven a connected unimodal (unicyclic) graph, find a minimum inversion count over simple paths visiting at least K vertices, or -1 if none exist.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Laser TowersOn a grid with directional laser towers and enemy counts, choose which towers fire and at which cell so lasers never intersect, maximizing enemies destroyed.	Hard8	GreedyBrute force+2	No attempts yet	2s	512 MB	Judgeable
Blue vertex distance sums on a treeProcess paint and distance-sum queries on a weighted tree, reporting for each query 2 the total distance from x to all blue vertices.	Hard8	TreePrefix sum+2	No attempts yet	5s	512 MB	Judgeable
Good SubstringsCount how many distinct substrings of a binary string appear twice at non-overlapping positions.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Number of RegionsGiven A and B, count the regions into which the A times B lines y = ax + b with 0 <= a < A, 0 <= b < B divide the plane.	Hard8	CombinatoricsGeometry+1	No attempts yet	2s	512 MB	Judgeable
Segments in a Regular PolygonCount the orders in which the remaining polygon vertices can be visited so each new segment crosses an existing one and the path closes back to P0.	Hard8	BacktrackingDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Counting ear shapesCount quadruples of red points and pairs of blue points forming an ear shape with angle and containment conditions.	Hard8	GeometryBrute force+2	No attempts yet	2s	512 MB	Judgeable
New Store NameSplit each of two short strings into two non-overlapping contiguous pieces so that A+C equals B+D, and output the lexicographically smallest longest result.	Hard8	StringBrute force+1	No attempts yet	2s	512 MB	Judgeable