Problems

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Total results29,414 problems

The Infosci Pirate Crew
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bang! Bang!
Hard8
Geometry, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hyunsoo City
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Directing the Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Parallel Lines
Hard8
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Medical Checkup
Hard8
Simulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Making the Perimeter of the Convex Hull Shortest
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pizza Delivery
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rendezvous on a Tetrahedron
Hard8
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Homework
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Starting a Scenic Railroad Service
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Puzzle
Hard8
String, Union-find+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Border Wall
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Homotopic Paths
Hard8
Geometry, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
New Country Division
Hard8
Graph, Minimum spanning tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Getting Back Home
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mars
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Wookje and His Fans
Hard8
Linked list, Union-find+2
No attempts yet
Time limit
2.5s
Memory limit
256 MB
Judgeable
Retro
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Portal
Hard8
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Winning Segments
Hard8
Bit manipulation, Prefix sum+2
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
K-summary
Hard8
Math, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
64 MB
Judgeable
Ceste
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2.5s
Memory limit
128 MB
Judgeable
Bureaucracy
Hard8
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
Pictionary
Hard8
Union-find, Number theory+2
No attempts yet
Time limit
1.5s
Memory limit
64 MB
Judgeable
Multiple of a Squared Factorial
Hard8
Number theory, Math+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Guardians of the Lunatics
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
The Grand Noi and ICPC Battle
Hard8
Segment tree, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
AdoraBalls
Hard8
Number theory, Math+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Balloon Distribution
Hard8
Binary search, Sorting+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Convex Quadrilateral
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
9s
Memory limit
512 MB
Judgeable
Handbags
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
11s
Memory limit
512 MB
Judgeable
Off the Rails
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Concert Attendance Schedules
Hard8
Dynamic programming, String
No attempts yet
Time limit
0.3s
Memory limit
128 MB
Judgeable
Christmas Tree
Hard8
Tree, DFS+2
No attempts yet
Time limit
0.7s
Memory limit
512 MB
Judgeable
Binary Transformations
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cat and Mouse
Hard8
Tree, DFS+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Tetris
Hard8
Dynamic programming, Simulation+2
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Cunning Friends
Hard8
Game theory, Greedy+2
No attempts yet
Time limit
2s
Memory limit
64 MB
Judgeable
French Dinner
Hard8
Shortest path, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Blowing Candles
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Canonical Coin Systems
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cat and Mice
Hard8
Binary search, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Umbral Decoding
Hard8
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Vera and the Banquet
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Vera and Canada Day
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Vera and the Engineering Buildings
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Computer Science
Hard8
Binary search, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Standing Out from the Herd
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Greedy Gift Takers
Hard8
Math, Simulation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Pie for a Pie
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A Simple Function
Hard8
Number theory, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Jet-Black Wings
Hard8
Trie, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
HH Country
Hard8
Tree, DFS+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Deforestation
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
LCA and queries
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Graph and Minimum Spanning Tree
Hard8
Minimum spanning tree, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
City Maintenance
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Picking Numbers on a Circle
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
K-Uniform String
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Arranging game levels
Hard8
Tree, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Programming Duel Tournament
Hard8
Greedy, Tree+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Making a Beautiful Puzzle
Hard8
Dynamic programming, Backtracking+2
No attempts yet
Time limit
3s
Memory limit
128 MB
Judgeable
Operation Optimization
Hard8
String, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Tree Separator
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Coin Slider
Hard8
Geometry, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Help the Princess!
Hard8
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Escape from Hell
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Share the Ruins Preservation
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multisect
Hard8
Dynamic programming, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Non-redundant Drive
Hard8
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Map of the Ninja House
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dango Maker
Hard8
Dynamic programming, Matrix+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Commuter Pass
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Maximum Interval Sum 2
Hard8
Segment tree, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Äventyr 2
Hard8
Tree, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Frogs 2
Hard8
Graph, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Blocks 4
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Mining
Hard8
Binary search, BFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Big Number Multiplication (2)
Hard8
Math, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lifeguards (Platinum)
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow at Large (Platinum)
Hard8
Tree, DFS+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Sprinklers
Hard8
Combinatorics, Divide and conquer+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow at Large
Hard8
Tree, BFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ascending Photo
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Connect the Dots
Hard8
Geometry, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Factor-Free Tree
Hard8
Tree, Divide and conquer+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Juggling Troupe
Hard8
Simulation, Greedy+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Broken Gearbox
Hard8
Graph, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Petrol
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pillars
Hard8
Implementation, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hit of the Season
Hard8
String, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Staging
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Cave
Hard8
Tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Captain
Hard8
Graph, Shortest path+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Drawing a Character Face
Hard8
Geometry, Math+2
No attempts yet
Time limit
0.1s
Memory limit
256 MB
Judgeable
Satan Game
Hard8
Probability, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two tetrominoes
Hard8
Brute force, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Spacetime Stone
Hard8
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Phantom Thief Gangsan
Hard8
Graph, Simulation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
The Infosci Pirate CrewGiven N islands with coordinates, treasure values, and safe hardness, choose a monotone northeast path and a hardness interval to maximize collected value minus interval length.	Hard8	Dynamic programmingSorting+2	No attempts yet	1s	512 MB	Judgeable
Bang! Bang!Given lines and circles all passing through the origin, count how many regions the plane is divided into, treating duplicates as one shape.	Hard8	GeometryCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Hyunsoo CityGiven a connected cactus graph with toggleable edges, answer connectivity queries under edge updates, where each edge lies on at most one cycle.	Hard8	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Directing the TreeCount the orientations of a tree's edges such that every given vertex pair has a directed path one way or the other, modulo 1e9+7.	Hard8	TreeDFS+2	No attempts yet	2s	256 MB	Judgeable
Parallel LinesGiven up to 16 distinct points, pair them up to maximize the number of parallel pairs among the drawn segments.	Hard8	Bit manipulationDynamic programming+2	No attempts yet	10s	512 MB	Judgeable
Medical CheckupGiven n students in a fixed queue and their per-item service times, report the item each student is on or waiting for at time t+0.5.	Hard8	SimulationMath+2	No attempts yet	2s	512 MB	Judgeable
Making the Perimeter of the Convex Hull ShortestGiven n points, find the largest decrease in convex hull perimeter achievable by removing exactly two of the points.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Pizza DeliveryGiven a directed weighted graph with source 1 and target 2, each day flips the direction of one distinct edge; report whether the shortest path distance shrinks, stays equal, or grows (or becomes unreachable).	Hard8	GraphShortest path+1	No attempts yet	2s	512 MB	Judgeable
Rendezvous on a TetrahedronTwo worms start at vertex A of a regular tetrahedron, crawl straight across faces reflecting off edges, and stop after integer trail lengths; decide whether they end on the same face.	Hard8	GeometryImplementation+1	No attempts yet	1s	512 MB	Judgeable
HomeworkGiven n assignments split into two courses with release days and deadlines, simulate fixed tie-break rules over adaptive coin choices and find the maximum and minimum number he can finish.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Starting a Scenic Railroad ServiceFor n travel segments, compute the minimum seats needed under arbitrary online seat choices and under optimal offline assignment.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
String PuzzleGiven equality hints between substrings of a huge implicit string plus some fixed letters, decide the letters at the queried positions. The hint structure is a partition of the string into sections, and a hint joins one section to an earlier same-length section, so the constraints are interval equalities on an unknown string of length n; the task is to propagate equality and fixed letters across positions, answering ? where a position's letter is not forced. The input size is small (at most 1000 hints and 1000 queries) but n can be 10^9, so positions cannot be enumerated directly and the hint/	Hard8	StringUnion-find+1	No attempts yet	2s	512 MB	Judgeable
Border WallGiven two colored point sets and a width d, find the minimum number of points to delete so that a strip of width d separates the remaining points by color.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Homotopic PathsDecide whether two polygonal paths from s to t in a plane with point obstacles are homotopic, that is, deformable into each other without crossing any tree.	Hard8	GeometryImplementation+2	No attempts yet	2s	512 MB	Judgeable
New Country DivisionSplit the graph's vertices into two sides with vertex 1 and vertex n on opposite sides so the XOR of cut-edge weights is maximized.	Hard8	GraphMinimum spanning tree+2	No attempts yet	2s	512 MB	Judgeable
Getting Back HomeOn a tree with home at node 1 and office at node n, find the smallest flashlight range d so that a random walk governed by visibility rules always reaches home within 10^9 steps.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
MarsFor each query substring, find the minimum number of bit flips that make it match no substring of the DNA, or report Impossible.	Hard8	String matchingDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Wookje and His FansMaintain a line of fans with club labels under deletions and range-count queries, where each query counts the maximal same-club run around an element.	Hard8	Linked listUnion-find+2	No attempts yet	2.5s	256 MB	Judgeable
RetroGiven a grid where the player moves horizontally while objects fall one row per turn, collect brackets to form the longest valid expression and output the lexicographically smallest one of that length.	Hard8	Dynamic programmingGreedy+2	No attempts yet	0.5s	512 MB	Judgeable
PortalFind the minimum time for Chell to reach F in a grid, where shooting portals into walls is free and stepping through a portal pair costs 1, with at most two portals alive at once.	Hard8	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
Winning SegmentsGiven a permutation of 0..2^M-1, count the nonempty subarrays whose XOR can be made equal to 2^M-1 by one mandatory swap of two elements.	Hard8	Bit manipulationPrefix sum+2	No attempts yet	4s	256 MB	Judgeable
K-summaryGiven segment lengths K_i, count how many array positions are pinned down by all the K_i-summaries.	Hard8	MathNumber theory+2	No attempts yet	0.5s	64 MB	Judgeable
CesteFor each city, find the route from city 1 that minimizes the product of total travel time and total cost, or report -1 if unreachable.	Hard8	GraphShortest path+2	No attempts yet	2.5s	128 MB	Judgeable
BureaucracySimulate repeatedly sending a task down the smallest-numbered child on each root-to-leaf path, paying 1,2,3,... coins up the chain, and deleting the leaf.	Hard8	TreeDFS+2	No attempts yet	1s	64 MB	Judgeable
PictionaryCities get roads on day i joining all pairs whose gcd is M-i+1; for each query, find the first day two given cities become connected.	Hard8	Union-findNumber theory+2	No attempts yet	1.5s	64 MB	Judgeable
Multiple of a Squared FactorialFor many queries N, find the smallest K such that K! is divisible by (N!)^2. The answer is always between N and 2N, and needs Legendre exponent checks.	Hard8	Number theoryMath+2	No attempts yet	3s	512 MB	Judgeable
Guardians of the LunaticsSplit a row of L cells into at most G contiguous nonempty blocks, where a block of length k multiplies each member's craziness by k, to minimize the total cost.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	7s	512 MB	Judgeable
The Grand Noi and ICPC BattleMaintain a sequence of N ones under range assignment and queries for the sum of A_i A_j A_k over all i<j<k in a range, modulo 10^8, with N up to 1e9 and Q up to 1e5.	Hard8	Segment treeDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
AdoraBallsGiven the counts of children in four colours and four bundle types, decide whether some non-negative number of each bundle can supply equal, positive balls to every child with none left over.	Hard8	Number theoryMath+2	No attempts yet	6s	512 MB	Judgeable
Balloon DistributionRank all ratios P_i/j from largest to smallest and count, for each contestant, how many ratios fall at rank N or above, with ties at the cutoff all counted.	Hard8	Binary searchSorting+2	No attempts yet	6s	512 MB	Judgeable
Convex QuadrilateralGiven n points, find the smallest-area convex quadrilateral whose four sides each pass through at least two of the points and that contains every point.	Hard8	GeometryGreedy+2	No attempts yet	9s	512 MB	Judgeable
HandbagsA grid of villages sets prices from s source prices; report the maximum price and how many villages reach it.	Hard8	Shortest pathGraph+1	No attempts yet	11s	512 MB	Judgeable
Off the RailsGiven n cities sorted by x, cover them with straight non-vertical segments so that the sum of squared vertical distances plus C per segment is minimized.	Hard8	Dynamic programmingGeometry+2	No attempts yet	5s	512 MB	Judgeable
Concert Attendance SchedulesCount the ways to pick increasing day positions matching a target band sequence, where each pick must wait h_b+1 days after that band's previous pick.	Hard8	Dynamic programmingString	No attempts yet	0.3s	128 MB	Judgeable
Christmas TreeGiven the final colours on a tree after M path-painting updates with distinct colours, reconstruct the unique valid update order and the endpoints of each colour's shortest covering path.	Hard8	TreeDFS+2	No attempts yet	0.7s	512 MB	Judgeable
Binary TransformationsGiven starting bits, target bits, and per-bit costs, flipping a bit i costs the sum of costs of all bits equal to 1 after the flip; find the minimum total price to reach the target.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
Cat and MouseOn a tree with distinct edge weights, the mouse always moves to its heaviest incident edge (or second heaviest if the cat blocks it); find the minimum number of mouse moves for the cat to trap it.	Hard8	TreeDFS+2	No attempts yet	10s	512 MB	Judgeable
TetrisOn a 3-wide, 10-tall Tetris board, pieces from a repeating shape sequence arrive forever; maximize how many land before the top fills, or output -1 if play can continue indefinitely.	Hard8	Dynamic programmingSimulation+2	No attempts yet	2.5s	512 MB	Judgeable
Cunning FriendsThree players take turns removing stones from piles; Ben and Chris cooperate to make Anthony lose, so decide whether Anthony can avoid defeat.	Hard8	Game theoryGreedy+2	No attempts yet	2s	64 MB	Judgeable
French DinnerDecide whether dishes can be assigned serving times satisfying simultaneity and precedence bounds while keeping the whole meal within K minutes.	Hard8	Shortest pathGraph+1	No attempts yet	2s	512 MB	Judgeable
Blowing CandlesGiven up to 200,000 points inside a disk, find the minimum width of a strip that can cover all of them.	Hard8	GeometryBrute force+2	No attempts yet	4s	512 MB	Judgeable
Canonical Coin SystemsGiven a sorted coin system, decide whether the greedy algorithm always makes change with the fewest coins, or whether some amount is a counterexample.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Cat and MiceFind the smallest initial speed v so the cat can visit all points in some order, each arrival at or before its deadline, with speed multiplied by m after every meal.	Hard8	Binary searchDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Umbral DecodingGiven up to 100 safe points (x, y, b), count lattice points (p, q) in the square [0, n]^2 that are not covered by any region \|x-p\|^3 + \|y-q\|^3 <= b.	Hard8	GeometryMath+1	No attempts yet	2s	512 MB	Judgeable
Vera and the BanquetGiven a circular string S, count the number of distinct substrings appearing in any contiguous block read in either direction around the circle.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Vera and Canada DayAfter each laser is added, choose one of four L-shaped firing orientations per laser so that the total awe from lasers hit by beams is maximized.	Hard8	Dynamic programmingGraph+2	No attempts yet	2s	512 MB	Judgeable
Vera and the Engineering BuildingsGiven a tree of N nodes with distinct hidden values and inspection costs, find the minimum total cost of an adaptive strategy that is guaranteed to locate a local maximum.	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Computer ScienceFind the smallest L such that for each a_i we can pick an interval [x_i, x_i+L] covering a_i and containing at least K of the given integers.	Hard8	Binary searchSorting+2	No attempts yet	2s	512 MB	Judgeable
Standing Out from the HerdFor each name in the herd, count its substrings that occur in no other name.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
Greedy Gift TakersEach cow takes a gift and reinserts herself c_i positions from the tail; count how many cows never reach the head.	Hard8	MathSimulation	No attempts yet	2s	512 MB	Judgeable
A Pie for a PieEach cow alternately returns a pie whose own tastiness is within D above the received pie; for each of Bessie's pies, find the fewest pies in an exchange ending with a zero-valued pie.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
A Simple FunctionDefine f via a Pascal-like recurrence that resets to 0 whenever the sum is divisible by prime M, and answer up to 10^4 queries f(a, b, M) modulo 10^9+7.	Hard8	Number theoryCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
The Jet-Black WingsMaintain a multiset under global XOR updates and queries asking for the sum of the K smallest elements.	Hard8	TrieBit manipulation+2	No attempts yet	3s	512 MB	Judgeable
HH CountryFor each query set of tree vertices, output twice the sum of pairwise tree distances.	Hard8	TreeDFS+1	No attempts yet	10s	512 MB	Judgeable
DeforestationCut trees in a grid so the top-left and bottom-right cells become connected, minimizing the total walking time to cut each tree and haul it back to the mill.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
LCA and queriesFor each query with a designated root r, report the LCA of u and v in a tree of up to 100,000 vertices.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Graph and Minimum Spanning TreeFor each edge of a connected weighted undirected graph, print the weight of a minimum spanning tree that is forced to include that edge.	Hard8	Minimum spanning treeUnion-find+2	No attempts yet	2s	512 MB	Judgeable
City MaintenanceGiven a tree with a price on every vertex, find the maximum, over all choices of a removed vertex, of the sum of the maximum price within each remaining connected component.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Picking Numbers on a CirclePick exactly K numbers from a circle of N values so that no two chosen are adjacent, maximizing the sum.	Hard8	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
K-Uniform StringCount binary strings of length N where, for each of M given intervals, every length-K substring inside it contains the same number of ones, modulo 1e9+7.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Arranging game levelsCount rooted tree arrangements of N levels where each level's clear score S_i and the cumulative score K_i along the root-to-level path are given, and children must have larger S than parents.	Hard8	TreeCombinatorics+2	No attempts yet	1s	256 MB	Judgeable
Programming Duel TournamentChoose a duel schedule for N contestants, where the higher skill always wins and each contestant duels at most L_i times, to maximize total duel XOR interest minus fatigue.	Hard8	GreedyTree+2	No attempts yet	2s	256 MB	Judgeable
Making a Beautiful PuzzleFill each square of an N by M board with one of four colors so that orthogonal neighbors differ, maximizing total beauty and counting optimal placements modulo 1e9+7.	Hard8	Dynamic programmingBacktracking+2	No attempts yet	3s	128 MB	Judgeable
Operation OptimizationFind the shortest sequence of append-0, append-1, and self-doubling operations whose two-fold application to the empty string yields a given binary string S.	Hard8	StringGreedy+2	No attempts yet	2s	256 MB	Judgeable
Tree SeparatorGiven a tree, delete all vertices on some simple path between two chosen vertices; maximize the number of remaining components of size at least K.	Hard8	TreeDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Coin SliderChoose the largest subset of at most 16 coins and an order of moves so no moving coin ever collides with a stationary or already-moved coin.	Hard8	GeometryBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Help the Princess!Decide whether a princess can reach the single escape hatch on a grid while any number of soldiers chase her simultaneously and catch her by sharing a cell.	Hard8	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Escape from HellChoose an order to use N energy drinks so the climber reaches length L on the earliest day without sinners catching up at night.	Hard8	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Share the Ruins PreservationSplit points by a vertical line that avoids all points, build the minimum-area enclosing convex hull of each side, and minimize the total area.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
MultisectGiven a hidden failing revision among n candidates and up to K simultaneous tests per round, find the strategy that minimizes expected total cost when a round with i failures costs T_i.	Hard8	Dynamic programmingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Non-redundant DriveIn a tree where each node gives g fuel and each edge costs d, find the longest simple path from any start such that the running fuel never drops below zero, refueling once per node.	Hard8	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Map of the Ninja HouseReconstruct the graph of a ninja house from the counter and door records produced by a fixed DFS exploration, handling back edges, skips, and multi-edges.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Dango MakerChoose disjoint horizontal or vertical runs of three cells reading R, G, W in order on an N by M grid, maximizing how many such sticks fit.	Hard8	Dynamic programmingMatrix+2	No attempts yet	2s	256 MB	Judgeable
Commuter PassPick a shortest S-T path to make free, then find the minimum U-V travel cost, where edges on that path cost 0 and others cost their fare.	Hard8	GraphShortest path+1	No attempts yet	2s	256 MB	Judgeable
Maximum Interval Sum 2For a sequence with point updates, answer range queries for the maximum of U times a subarray sum plus V times its length minus one.	Hard8	Segment treeDivide and conquer+2	No attempts yet	1s	256 MB	Judgeable
Äventyr 2On a tree, timelines get marked over time, and after each mark you must report the distance from a queried vertex to the nearest marked vertex.	Hard8	TreeBFS+2	No attempts yet	1s	256 MB	Judgeable
Frogs 2Assign one frog to each pad so that every frog sits on a preferred pad and each log joins two frogs with equal interest in the log's topic.	Hard8	GraphBacktracking+2	No attempts yet	1s	256 MB	Judgeable
Blocks 4Count the tilings of an N by M rectangle using blocks of size k by N (rotatable) for k from 1 to N, modulo 1999, where M can be as large as 1e10.	Hard8	Dynamic programmingMath+2	No attempts yet	1s	256 MB	Judgeable
MiningGiven a grid of mineral strengths with air only on the top, left, and right faces, find the smallest performance D so that at least K minerals can be removed in some order.	Hard8	Binary searchBFS+2	No attempts yet	2s	256 MB	Judgeable
Big Number Multiplication (2)Multiply two integers of up to 300,000 digits each, too large for quadratic multiplication, and print the exact product.	Hard8	MathDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Lifeguards (Platinum)Fire exactly K of N lifeguard shifts to maximize the total time covered by at least one remaining shift.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
Cow at Large (Platinum)In a tree, for each barn find the minimum number of farmers placed at exits needed to catch Bessie, who starts there and runs for the nearest exit at equal speed.	Hard8	TreeDFS+2	No attempts yet	4s	512 MB	Judgeable
SprinklersGiven a permutation of N sprinklers, count axis-aligned integer rectangles whose every point lies both northeast of some sprinkler and southwest of another, modulo 1e9+7.	Hard8	CombinatoricsDivide and conquer+2	No attempts yet	2s	512 MB	Judgeable
Cow at LargeOn a tree of N barns, find the minimum number of farmers placed at exits so they catch Bessie, who starts at node K and runs to any exit.	Hard8	TreeBFS+1	No attempts yet	2s	512 MB	Judgeable
Ascending PhotoGiven a sequence of n heights, find the minimum number of cuts so the pieces can be reordered into a nondecreasing sequence.	Hard8	GreedySorting+2	No attempts yet	3s	512 MB	Judgeable
Connect the DotsGiven a 4 by 4 grid labeled 1 to 16, find the minimum number of straight segments a continuous polyline needs so that the dots are visited in numeric order.	Hard8	GeometryGreedy+2	No attempts yet	2s	512 MB	Judgeable
Factor-Free TreeGiven a sequence, decide whether it can be the inorder of a rooted binary tree where every node is coprime with all its ancestors, and if so output each node's parent index.	Hard8	TreeDivide and conquer+2	No attempts yet	6s	512 MB	Judgeable
Juggling TroupeSimulate balls thrown left and right simultaneously until every position holds at most one ball, then report the final configuration.	Hard8	SimulationGreedy+2	No attempts yet	3s	512 MB	Judgeable
Broken GearboxAssign each of n gear radii to a vertex of a connected graph so that every edge's distance equals the sum of its assigned radii, returning the lexicographically smallest assignment or impossible.	Hard8	GraphMath+2	No attempts yet	2s	512 MB	Judgeable
PetrolGiven a weighted graph with some marked stations, answer queries asking whether a tanker of capacity b can travel from station x to station y, refuelling only at stations.	Hard8	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
PillarsGiven a grid with 2x2 pillars spaced apart, construct the unique Hamiltonian circuit through all free cells defined by a fixed local rule.	Hard8	ImplementationSimulation+2	No attempts yet	2s	512 MB	Judgeable
Hit of the SeasonFind the shortest print matrix over R, G, B that can reproduce a wallpaper string, where specified stripes must never be overprinted and at most 19 stripes are unspecified.	Hard8	StringBrute force+2	No attempts yet	2s	512 MB	Judgeable
The StagingGiven n gangsters each aiming at a distinct target, count survivors after each of q updates to the shooting time of one gangster.	Hard8	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
The CaveOn a tree, decide whether one chamber lies on some walk from a_i to b_i using at most d_i edges, for every speleologist, and output the smallest such chamber.	Hard8	TreeGraph+2	No attempts yet	2s	512 MB	Judgeable
The CaptainFind the minimum total north-south distance the Captain must steer on a route from island 1 to island n, where he handles one axis per leg.	Hard8	GraphShortest path+1	No attempts yet	2s	512 MB	Judgeable
Drawing a Character FaceGiven three circles, compute the area of their union, counting overlaps once, and print it to six decimal places.	Hard8	GeometryMath+2	No attempts yet	0.1s	256 MB	Judgeable
Satan GameOutput a board with N up to 100, M up to 20, and snakes and ladders so the expected number of dice rolls to finish is at least 5e18.	Hard8	ProbabilityMath+1	No attempts yet	2s	512 MB	Judgeable
Two tetrominoesPlace two non-overlapping tetrominoes anywhere on an N by M grid so the total of the covered cells is maximized.	Hard8	Brute forceDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Spacetime StoneAssign Taekhee's cards to rounds and pick a strength-joker round so that Namgyu's best-case score (over his joker round) is minimized, ties broken lexicographically.	Hard8	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Phantom Thief GangsanDecide whether a thief can collect all jewels and end with zero trackers by repeatedly walking whole rows or columns, never re-entering a row or column after stealing a plain jewel.	Hard8	GraphSimulation+2	No attempts yet	1s	128 MB	Judgeable