Problems

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Total results29,342 problems

Travel Tax
Hard8
Tree, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Laying Out a Network
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Deposit
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Lasers
Hard8
Geometry, Binary search+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Wheel
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Match of the Century
Hard8
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Forest Phenomenon
Hard8
Probability, Math+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Olympiad
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Mluran Storage
Hard8
Graph, Math+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Planet Defense
Hard8
Math, Sorting+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Interference
Hard8
Math, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Cipher Key
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Choosing Problems
Hard8
Backtracking, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Text Editor
Hard8
Segment tree, Stack+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Road Reform
Hard8
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Label
Hard8
String matching, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Time Shift
Hard8
Sorting, Prefix sum+2
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Archiver
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
3s
Memory limit
256 MB
Judgeable
Viruses
Hard8
Dynamic programming, Trie+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Rails
Hard8
Geometry, Hash map+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Political Development
Hard8
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Railway
Hard8
Tree, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Toll
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Plus Minus
Hard8
Combinatorics, Union-find+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Repeats
Hard8
String, String matching+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Car Park
Hard8
BFS, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Table 10
Hard8
Backtracking, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gahui and the Airplane
Hard8
Combinatorics, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Beautiful Mountains
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fascinating Partitions
Hard8
Dynamic programming, Divide and conquer+2
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Game of Slots
Hard8
Combinatorics, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Halting Wolf
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Impenetrable Wall
Hard8
Geometry, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
May I Add a Letter?
Hard8
String, String matching+1
No attempts yet
Time limit
2.5s
Memory limit
1024 MB
Judgeable
Two Shortest Paths
Hard8
Graph, Shortest path
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Driving Lanes
Hard8
Dynamic programming, Implementation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
twOBoOgEr
Hard8
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Tree Colors and Queries 2
Hard8
Tree, Union-find+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
XOR 5
Hard8
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
XOR 6
Hard8
Prefix sum, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Longest Common Balanced Substring
Hard8
String matching, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Fence Posts
Hard8
Prefix sum, Sliding window+2
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Ski Resort
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Making UCPC
Hard8
Tree, DFS+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Must Stay Hidden
Hard8
Graph, Shortest path+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Edamame Energy Engineering
Hard8
Two pointers, Implementation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Rebound Sequences
Hard8
Dynamic programming, Combinatorics
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Surround the Castle
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Yet Another Expression Mining
Hard8
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Aggressive Traveller
Hard8
Graph, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Irreversible Reactions
Hard8
Graph, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
String Magic
Hard8
Dynamic programming, String+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Mysterious Button
Hard8
Dynamic programming, Matrix+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Divide and Conquer
Hard8
Graph, Divide and conquer+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Casino
Hard8
Dynamic programming, Probability+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Rings and Strings
Hard8
Dynamic programming, Graph+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Prison
Hard8
Math, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pitch-Black Room
Hard8
Graph, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Almost Periodic String
Hard8
String, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Escape
Hard8
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bit Operation Game
Hard8
Game theory, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alternate Escape
Hard8
Graph, Game theory+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
1 Day Passport
Hard8
Shortest path, Bit manipulation+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Wish upon a shooting star
Hard8
Simulation, Geometry+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Koto Distance
Hard8
Geometry, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Evacuation Route
Hard8
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Apples
Hard8
Geometry, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
TiMe Table
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Social Monsters
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Perm Query
Hard8
Math, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Unordered Operators
Hard8
Dynamic programming, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A + B
Hard8
Bit manipulation, Segment tree
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Sister Ports
Hard8
Dynamic programming, Geometry+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Longest Increasing Sequence
Hard8
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
DNA
Hard8
Dynamic programming, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Substring
Hard8
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Enumeration
Hard8
Probability, Combinatorics+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Sun and Moon
Hard8
Math, Number theory
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Usoperanto
Hard8
Greedy, Tree+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Common Palindromes
Hard8
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
On or Off
Hard8
Tree, Dynamic programming+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Marathon Match
Hard8
Probability, Dynamic programming+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Beautiful Currency
Hard8
Binary search, Greedy+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Vector Compression
Hard8
Greedy, Geometry+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Scribbling Witch
Hard8
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Set-constructing Witch
Hard8
Dynamic programming, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
6÷2(1+2)
Hard8
Dynamic programming, Brute force+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Divide the Cake
Hard8
Geometry, Probability+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Sakura Poetry
Hard8
Dynamic programming, String matching+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Light Road
Hard8
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Network Reliability
Hard8
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Mr. Rito's Post Office
Hard8
Dynamic programming, Shortest path+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Immortal Jewels
Hard8
Geometry, Brute force+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
My Friends Are Small
Hard8
Dynamic programming, Sorting+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Ten-Year-Old Dynamic Programming
Hard8
Combinatorics, Dynamic programming+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Cat Pot Remodeling Plan (Tentative)
Hard8
Sorting, Two pointers+1
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
Carrot Tour
Hard8
Dynamic programming, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Usagitobi
Hard8
Graph, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dungeon Wall
Hard8
BFS, Graph+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable
How to Create a Good Game
Hard8
Graph, Dynamic programming+2
No attempts yet
Time limit
8s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Travel TaxIn a tree of n cities, each road has a toll range [l, r]; count assignments of tolls whose total weighted income (each road weighted by how many shortest paths cross it) equals m, modulo 1e9+7.	Hard8	TreeCombinatorics+2	No attempts yet	2s	256 MB	Judgeable
Laying Out a NetworkPlace n computers and m capacity-limited switches around a circular table; connect every computer to a switch, minimizing total cable length given by circular distance.	Hard8	Dynamic programmingGreedy+2	No attempts yet	3s	256 MB	Judgeable
DepositEach year Vasily can move money between banks after paying fixed withdrawal fees, and the task is to maximize the final total after m years.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	256 MB	Judgeable
LasersGiven n points where a laser sits at the first and refractors at the rest, find the minimum voltage a so a beam can be bent back to its start, where each turn angle is bounded by a.	Hard8	GeometryBinary search+2	No attempts yet	2s	256 MB	Judgeable
WheelEach city on a wheel graph is captured by one of two parties at random; find the expected size of the largest connected group of cities held by a single party.	Hard8	Dynamic programmingProbability+2	No attempts yet	2s	256 MB	Judgeable
Match of the CenturyGiven 2n distinct heights, randomly split into two teams of n, then order one team by decreasing height and the other by increasing height; find the expected sum of same-position height differences.	Hard8	CombinatoricsMath+2	No attempts yet	2s	256 MB	Judgeable
Forest PhenomenonFor each n by m grid, every cell ships its firewood to a uniformly random orthogonal neighbor; find the expected number of cells that end up with at least one shipment.	Hard8	ProbabilityMath+2	No attempts yet	2s	256 MB	Judgeable
OlympiadGiven three rectangles with fixed side lengths, arrange them axis-parallel so the union covers the least area, allowing overlaps.	Hard8	GeometryBrute force+2	No attempts yet	1s	256 MB	Judgeable
Mluran StorageCount the ways to 2-color isotopes 1..n so that no two masses summing to a given power-of-two critical number share a color, mod 1e9+7.	Hard8	GraphMath+2	No attempts yet	2s	256 MB	Judgeable
Planet DefenseGiven each asteroid's initial position and constant velocity, count for each queried integer time how many asteroids lie strictly within distance R of the origin.	Hard8	MathSorting+2	No attempts yet	2s	256 MB	Judgeable
InterferenceFor each received n-bit string (n up to 34) and target polynomial hash, find a string within minimum Hamming distance whose hash matches, and report the flipped bit indices.	Hard8	MathDynamic programming+2	No attempts yet	2s	256 MB	Judgeable
Cipher KeyGiven encrypted strings, recover for each the longest string s such that s is a prefix and reversed s is a suffix of some substring t, maximizing t.	Hard8	StringString matching+2	No attempts yet	2s	256 MB	Judgeable
Choosing ProblemsChoose d problems, one per difficulty level, so that every one of m topics appears exactly once across the chosen problems.	Hard8	BacktrackingBit manipulation+2	No attempts yet	2s	256 MB	Judgeable
Text EditorMaintain a string of parentheses and letters under point updates, and after each update that sets a parenthesis, report the position of its matching bracket or -1.	Hard8	Segment treeStack+2	No attempts yet	2s	256 MB	Judgeable
Road ReformCount ordered pairs (removed edge, added edge) that make the graph connected after the swap, where the added edge is not already present.	Hard8	GraphUnion-find+2	No attempts yet	2s	256 MB	Judgeable
LabelCount the cyclic shifts t of the concatenated label that split into dictionary words separated by one or more dots, and list them.	Hard8	String matchingDynamic programming+1	No attempts yet	2s	256 MB	Judgeable
Time ShiftGiven daily clock shifts in n cities over a year, compute the sum over all hours of the pairwise absolute differences of each city's elapsed time from the capital.	Hard8	SortingPrefix sum+2	No attempts yet	3s	256 MB	Judgeable
ArchiverAt each phase, replace the sequence of length n with one of length ceil(n/2), picking each new element from either end of its mirror pair; count a penalty whenever the two candidates differ, and minimize the total penalty.	Hard8	Dynamic programmingGreedy+1	No attempts yet	3s	256 MB	Judgeable
VirusesCount length-n strings over lowercase letters in which every position lies inside some substring that matches one of the m given virus patterns, modulo 1e9+7.	Hard8	Dynamic programmingTrie+2	No attempts yet	2s	256 MB	Judgeable
RailsGiven 2n distinct lines, pair them so each pair has two parallel lines at the same distance d, and find the smallest such d.	Hard8	GeometryHash map+2	No attempts yet	2s	256 MB	Judgeable
Political DevelopmentGiven a graph where every nonempty subset has a vertex of degree under K inside it, find the largest set of mutually disagreeing members (a maximum clique), guaranteed to be at most K.	Hard8	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
RailwayGiven a tree and m sets of vertices, count for each tree edge how many sets contain a path covering it, and list edges covered by at least k sets.	Hard8	TreePrefix sum+2	No attempts yet	1s	512 MB	Judgeable
TollGiven a layered directed graph where every edge jumps from one block of K nodes to the next, answer queries for the cheapest path cost between two nodes, or -1 if none exists.	Hard8	GraphDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Plus MinusCount the spin grids on an N by M board, consistent with K fixed cells, where every 2 by 2 block has two pluses and two minuses, modulo 1e9+7.	Hard8	CombinatoricsUnion-find+2	No attempts yet	1s	512 MB	Judgeable
RepeatsGiven a binary string of length n, find a substring that is some seed repeated as many times as possible, and report the count, seed length, and 1-based start position.	Hard8	StringString matching+2	No attempts yet	6s	512 MB	Judgeable
Car ParkA 6x6 parking lot holds 2x1 and 3x1 cars that slide only along their long axis; find the fewest single-square moves to drive car 1 out the row-3 exit, or -1 if impossible.	Hard8	BFSSimulation+2	No attempts yet	1s	512 MB	Judgeable
Table 10Build an N by N digit table (2 <= N <= 10) where every row, column, and main diagonal reads as a distinct multiple of M with no leading zero.	Hard8	BacktrackingBrute force+2	No attempts yet	1s	512 MB	Judgeable
Gahui and the AirplaneCount the flight paths of horizontal length d that start and end at altitude 0, stay positive in between, and consist of straight constant-slope segments, modulo a prime m.	Hard8	CombinatoricsNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Beautiful MountainsGiven an array where some entries are unknown, decide whether the unknown positive values can be filled so the array splits into equal-length mountains, with the last block allowed to be shorter.	Hard8	GreedyImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Fascinating PartitionsFor every k from 1 to N, compute the minimum and maximum total cost of splitting the array into exactly k contiguous subarrays, where a subarray costs its maximum element.	Hard8	Dynamic programmingDivide and conquer+2	No attempts yet	2.5s	1024 MB	Judgeable
Game of SlotsAlice arranges her cards into slots first, then Bob responds; compute Alice's optimal expected score when all card values are drawn uniformly from [1, 10^18].	Hard8	CombinatoricsGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Halting WolfGiven a program of finite and infinite jumps, find how many times instruction 1 can run, or report that it can run forever.	Hard8	GraphDFS+2	No attempts yet	1s	1024 MB	Judgeable
Impenetrable WallCount simple polygons through a fixed gate vertex, using tower vertices only, that strictly contain the house, are star-shaped from it, and have all tower angles convex, modulo 1e9+7.	Hard8	GeometryDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
May I Add a Letter?Given a string that changes by appending a character or deleting the last one, report after each update how many distinct substrings occur at least twice.	Hard8	StringString matching+1	No attempts yet	2.5s	1024 MB	Judgeable
Two Shortest PathsGiven a directed weighted graph, find for each vertex i the minimum total cost of two edge-disjoint paths from vertex 1 to i.	Hard8	GraphShortest path	No attempts yet	5s	1024 MB	Judgeable
Driving LanesGiven n straightaways separated by n-1 curves whose cost grows by c per lane, find the minimum total distance from lane 1 back to lane 1, where lane changes cost k+r and must fit within a straightaway.	Hard8	Dynamic programmingImplementation+1	No attempts yet	2s	512 MB	Judgeable
twOBoOgErCount every collision (A-B or A-wall) when B of mass n kg hits resting A of mass 1 kg elastically between a wall and B, for n up to 10^6.	Hard8	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
Tree Colors and Queries 2Given a rooted tree with colored vertices, cut parent edges online and count the distinct colors among the vertices still connected to each queried vertex.	Hard8	TreeUnion-find+1	No attempts yet	2s	256 MB	Judgeable
XOR 5Given an N by N black-and-white image, write a file of rectangle XOR operations that turns an all-white screen into the image using as few operations as possible.	Hard8	GreedyImplementation+2	No attempts yet	1s	512 MB	Judgeable
XOR 6Given an N by N binary image, find the minimum number of rectangle XOR (pixel-flip) operations that produce it from an all-white screen.	Hard8	Prefix sumGreedy+2	No attempts yet	1s	512 MB	Judgeable
Longest Common Balanced SubstringGiven two bracket strings A and B, find the length of the longest string that is a valid bracket sequence and a substring of both, or 0 if none exists.	Hard8	String matchingPrefix sum+1	No attempts yet	3s	1024 MB	Judgeable
Fence PostsGiven post heights and per-post costs to raise or lower them by 1 cm, find the minimum total cost so that some K consecutive posts end at the same height.	Hard8	Prefix sumSliding window+2	No attempts yet	5s	1024 MB	Judgeable
Ski ResortGiven a DAG of ski courses that always descend, and lifts that always ascend and can be ridden at most K times, maximize total skiing time from S to T.	Hard8	GraphDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Making UCPCGiven a tree whose vertices are labeled U, C, or P, count pairs (a, b) whose path letters can be rearranged into (UCPC)^k for some k >= 1.	Hard8	TreeDFS+2	No attempts yet	3s	1024 MB	Judgeable
Must Stay HiddenGiven N axis-aligned square sensors on a grid, find the minimum number to destroy so a monotone shortest path from (sx,sy) to (gx,gy) avoids all remaining sensors.	Hard8	GraphShortest path+2	No attempts yet	8s	512 MB	Judgeable
Edamame Energy EngineeringChoose a subset of N chemicals and a contiguous block of beans so that every bean in the block is satisfied by one of its two literal properties, maximizing the block length.	Hard8	Two pointersImplementation+2	No attempts yet	8s	512 MB	Judgeable
Rebound SequencesCount distinct rearrangements of the given multiset that contain indices i<j<k with a_i > a_k > a_j, modulo 1000000007.	Hard8	Dynamic programmingCombinatorics	No attempts yet	2s	512 MB	Judgeable
Surround the CastleGiven an R by C grid with one castle and plain cells that each have a moat cost, find the minimum total cost of moat cells that enclose the castle.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Yet Another Expression MiningCount subsequences of a string of digits and plus signs, with no leading, trailing, or doubled plus, whose arithmetic evaluation equals A.	Hard8	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Aggressive TravellerFind the most passport stamps you can collect on a walk from S to T in a directed graph, where some countries allow only limited stamps.	Hard8	GraphDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Irreversible ReactionsGiven a directed graph with random transitions, find the expected time to leave the set of states that can still return to the start, or report infinity.	Hard8	GraphProbability+2	No attempts yet	2s	512 MB	Judgeable
String MagicGiven costs for insert, delete, replace, and rotate-first-to-end, find the cheapest way to turn string X into string Y.	Hard8	Dynamic programmingString+2	No attempts yet	8s	512 MB	Judgeable
Mysterious ButtonFor each query, count the button press sequences from room 1 that end by escaping from room d and collect exactly e coins.	Hard8	Dynamic programmingMatrix+1	No attempts yet	8s	512 MB	Judgeable
Divide and ConquerSplit the cities of a connected graph into three independent sets where two of them have equal size, and list all achievable equal sizes.	Hard8	GraphDivide and conquer+2	No attempts yet	8s	512 MB	Judgeable
CasinoRoll N dice up to M times, stopping whenever you like, and find the expected score under the optimal stopping strategy.	Hard8	Dynamic programmingProbability+2	No attempts yet	8s	512 MB	Judgeable
Rings and StringsGiven N rings and the black strings between them, choose a subset of rings to hang so that the number of black strings between hung and unhung rings is maximized.	Hard8	Dynamic programmingGraph+1	No attempts yet	10s	512 MB	Judgeable
PrisonSimulate a process that repeatedly removes multiples of k from an infinite list of prisoners and renumbers, then report the original label released on step N.	Hard8	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Pitch-Black RoomFind the shortest fixed sequence of edge choices that leads every starting room to a bright room, regardless of where A starts.	Hard8	GraphBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Almost Periodic StringFor each query, decide whether the substring S[l..r] can be turned into a string of period t by changing at most one character.	Hard8	StringHash map+2	No attempts yet	2s	512 MB	Judgeable
EscapeStarting at vertex 1 in a connected undirected graph, walk without immediately reusing the edge you just came from, collecting each vertex's value the first time you visit it, and maximize the total.	Hard8	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Bit Operation GameFind the final value of T for each query (X, Y) when Alice and Bob alternately walk down a rooted tree and apply bitwise operations with X or Y.	Hard8	Game theoryTree+2	No attempts yet	2s	512 MB	Judgeable
Alternate EscapeOn a grid where walls can all be inverted by Bob on his turn, decide whether Alice can walk the token off the board against optimal play.	Hard8	GraphGame theory+2	No attempts yet	8s	512 MB	Judgeable
1 Day PassportFind the cheapest combination of unlimited-ride company passes and per-ride fares to travel from station S to T within H hours, where every train departs only on the hour.	Hard8	Shortest pathBit manipulation+2	No attempts yet	8s	512 MB	Judgeable
Wish upon a shooting starGiven moving spheres whose radii shrink linearly, find the vanish time of each, where touching pairs annihilate each other, in order.	Hard8	SimulationGeometry+2	No attempts yet	8s	512 MB	Judgeable
Koto DistanceGiven N access points, each covering points whose Koto distance (the minimum of the x-gap and y-gap) is at most w_i, decide whether their union covers the whole W by H rectangle.	Hard8	GeometrySorting+2	No attempts yet	2s	512 MB	Judgeable
Evacuation RouteOn a line of W cells, each an exit, entrance, or fire door with a seal time, find the maximum number of people who can reach an exit, where each entrance emits one person per time step.	Hard8	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
ApplesEach of N people carries an apple and moves at constant velocity; find the maximum number of apples a single infinite-speed straight-line shot fired at some time t >= 0 can pass through.	Hard8	GeometryMath+2	No attempts yet	5s	512 MB	Judgeable
TiMe TableChoose departure times for M buses along a line of S stops so that the total waiting time of N passengers, each arriving at a given stop at a given time, is minimized.	Hard8	Dynamic programmingSorting+2	No attempts yet	2s	512 MB	Judgeable
Social MonstersChoose K monsters maximizing total friendship, where given pairs have weight c (0 means the pair is forbidden) and all other pairs weigh 0. Each monster appears in at most two given pairs.	Hard8	GraphDynamic programming+2	No attempts yet	3s	512 MB	Judgeable
Perm QueryGiven a permutation whose cycles all have length at most 40, answer queries summing iterates of the permutation on an interval until the interval returns to the identity.	Hard8	MathPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Unordered OperatorsGiven an expression with +, -, * and parentheses, choose one precedence order for the three operators so the left-associative evaluation is maximized.	Hard8	Dynamic programmingBrute force+2	No attempts yet	2s	512 MB	Judgeable
A + BGiven binary numbers A and B, answer the maximum popcount of x in [A, A+B) after bit flips to A or B.	Hard8	Bit manipulationSegment tree	No attempts yet	8s	512 MB	Judgeable
Sister PortsCount the perfect matchings of a planar graph formed by a convex polygon's boundary plus non-crossing chords, modulo 1000003.	Hard8	Dynamic programmingGeometry+2	No attempts yet	8s	512 MB	Judgeable
Longest Increasing SequenceSplit a sequence into the maximum number of contiguous blocks whose sums form a strictly increasing sequence, and output the divider positions.	Hard8	Dynamic programmingPrefix sum+2	No attempts yet	5s	512 MB	Judgeable
DNAGiven a context-free grammar over DNA letters and target counts of A, T, G, C, count the strings the grammar generates with exactly those letter counts, modulo 1e9+7.	Hard8	Dynamic programmingMath+2	No attempts yet	2s	512 MB	Judgeable
SubstringA window [l, r] over a string moves by changing one endpoint at a time, and after each of m queries you must count how many distinct substring values have appeared across all windows visited.	Hard8	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
EnumerationEach integer a_k is chosen independently with probability p_k%, and we need the expected count of numbers in [1,m] divisible by at least one chosen integer.	Hard8	ProbabilityCombinatorics+2	No attempts yet	5s	512 MB	Judgeable
Sun and MoonFind the smallest positive day x at which the Sun and Moon power totals can match, with the option of skipping the Sun ritual.	Hard8	MathNumber theory	No attempts yet	5s	512 MB	Judgeable
UsoperantoGiven words where each word modifies at most one other word, order all words to minimize the total letter distance between each modifier and its modifiee, then report that minimum cost.	Hard8	GreedyTree+2	No attempts yet	8s	512 MB	Judgeable
Common PalindromesCount pairs of intervals, one in S and one in T, whose substrings are equal and palindromic; lengths up to 50,000.	Hard8	StringString matching+2	No attempts yet	2s	512 MB	Judgeable
On or OffIn a tree-shaped grid of rooms, visit M target rooms in order, choosing when to leave lights on or off so the total power plus switching cost is minimal.	Hard8	TreeDynamic programming+2	No attempts yet	7s	512 MB	Judgeable
Marathon MatchFor each of N runners who may rest at each of M stops with given probabilities, compute the probability that the runner finishes in strictly least time.	Hard8	ProbabilityDynamic programming+2	No attempts yet	5s	512 MB	Judgeable
Beautiful CurrencyGiven N increasing coin values, assign new positive integers so each value divides the next, minimizing the maximum relative change \|a_i - b_i\| / a_i.	Hard8	Binary searchGreedy+2	No attempts yet	5s	512 MB	Judgeable
Vector CompressionGiven M vectors in N dimensions and a free ordering, minimize the total squared length when each vector is stored either as is or as the residual after subtracting a real multiple of an earlier vector.	Hard8	GreedyGeometry+2	No attempts yet	5s	512 MB	Judgeable
Scribbling WitchFill the unknown cells of a grid so black cells form one tree and no two white cells share an edge, maximizing the black count.	Hard8	Dynamic programmingBit manipulation+1	No attempts yet	3s	512 MB	Judgeable
Set-constructing WitchEach synthesis rule combines several distinct witches into one new witch; find the minimum number of special Grief Seeds (at most one copy of each witch kind at a time) needed to produce witch T from easily obtainable witches.	Hard8	Dynamic programmingGreedy+2	No attempts yet	2s	512 MB	Judgeable
6÷2(1+2)Count the distinct integer results obtainable by parenthesizing an expression in any order, with integer division truncated toward zero and division by zero treated as invalid.	Hard8	Dynamic programmingBrute force+2	No attempts yet	8s	512 MB	Judgeable
Divide the CakeGiven 2N strawberry points on a W by H cake, find the probability that two uniformly random points, one on each vertical side, define a line splitting the strawberries into N and N.	Hard8	GeometryProbability+2	No attempts yet	8s	512 MB	Judgeable
Sakura PoetryCount word sequences of total length M following a directed word-connection graph, such that the concatenated string contains exactly one season word exactly once, modulo 1e9+7.	Hard8	Dynamic programmingString matching+2	No attempts yet	8s	512 MB	Judgeable
Light RoadPlace up to A P-mirrors and A Q-mirrors on a grid with obstacles so the southward laser beam reaches the creature, minimizing mirrors used.	Hard8	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Network ReliabilityEach edge of an undirected graph vanishes independently with the same probability; find the probability that what remains is connected.	Hard8	Dynamic programmingBit manipulation+2	No attempts yet	3s	512 MB	Judgeable
Mr. Rito's Post OfficeGiven a graph with land and sea edges and a fixed delivery order, find the shortest time to deliver in order while tracking the boat's location, since sea travel requires the boat.	Hard8	Dynamic programmingShortest path+2	No attempts yet	8s	512 MB	Judgeable
Immortal JewelsPlace an infinite line so it touches as many disjoint circles as possible without crossing any, where circle i is usable only if the line's distance to its surface is at most m_i.	Hard8	GeometryBrute force+2	No attempts yet	8s	512 MB	Judgeable
My Friends Are SmallCount subsets of friend weights that can be the final backpack load when items are added one by one in any order until no further friend fits under weight limit W.	Hard8	Dynamic programmingSorting+2	No attempts yet	8s	512 MB	Judgeable
Ten-Year-Old Dynamic ProgrammingCount monotone grid paths from (0,0) to (N,M) that contain exactly K backward steps (left or down), allowing the walk to overshoot the target and never step to a negative coordinate, modulo 1e9+7.	Hard8	CombinatoricsDynamic programming+2	No attempts yet	8s	512 MB	Judgeable
Cat Pot Remodeling Plan (Tentative)Pick male cats for pot A and female cats for pot B, each pot weighing at most W, to minimize the larger of the weight gap and the Cute range.	Hard8	SortingTwo pointers+1	No attempts yet	8s	512 MB	Judgeable
Carrot TourA rabbit walks a polyline of total length at most r, turning at most theta at each corner, earning one carrot per visited city; maximize carrots.	Hard8	Dynamic programmingGraph+2	No attempts yet	1s	512 MB	Judgeable
UsagitobiA rabbit on an m by n torus jumps by two fixed offset vectors; find the maximum number of jumps without revisiting a cell.	Hard8	GraphDFS+2	No attempts yet	1s	512 MB	Judgeable
Dungeon WallGiven a grid with internal walls, add one unit-length wall to maximize the increase in the shortest entrance-to-exit path length, keeping the path connected.	Hard8	BFSGraph+2	No attempts yet	8s	512 MB	Judgeable
How to Create a Good GameA DAG with weighted edges has each edge weight increased as much as possible without raising the longest path from node 0 to node N-1. Output the total added weight.	Hard8	GraphDynamic programming+2	No attempts yet	8s	512 MB	Judgeable