Problems

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

Under construction

Still being built. Things may change

Total results29,366 problems

Even More Secure Prison
Medium6
Array, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Painting a Tree
Medium6
Tree, Segment tree
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Explosive Staircase
Medium6
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Palindrome Cipher
Medium6
String matching, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
We Need More Energy
Medium6
Dynamic programming, Prefix sum
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Final Confrontation
Medium6
Two pointers, Sliding window+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Become Stronger
Medium6
Sorting, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Robot Production
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
In Pursuit of the Penguin
Medium6
Math, Number theory
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Unusual Trap
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Smeshariki Gathering Time
Medium6
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ramsey Theory
Medium6
Graph, Backtracking+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Pyramid Search
Medium6
Segment tree, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Day Off
Medium6
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bridges
Medium6
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Work From Home
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Acorn String
Medium6
Dynamic programming, Matrix
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Geysers
Medium6
Sorting, Geometry+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candy
Medium6
Dynamic programming, Array
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
The Tragedy of the Decreasing Growth Rate 1
Medium6
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Defend Jaewoo's Pass!
Medium6
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Building the Robot Convergence Hall
Medium6
Game theory, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Jaewoo's Card Gamble
Medium6
Dynamic programming, Probability
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum=Product
Medium6
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
RLE Inversion Counting
Medium6
Sorting, Segment tree+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Gibonni
Medium6
Backtracking, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tricolor Flag
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Squirrels
Medium6
Minimum spanning tree, Tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Wooden Lock
Medium6
Tree, BFS
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Diamonds
Medium6
Graph, Combinatorics
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Crazy Dance
Medium6
Math, Binary search
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Arithmetic and Dice
Medium6
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tennis Score
Medium6
Number theory, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Trouble with the Token
Medium6
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Shifting Boxes and a Caesar Cipher
Medium6
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Road Construction
Medium6
Math, Game theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Repairing an Array
Medium6
Array, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Code Lock
Medium6
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Bulk Purchase
Medium6
Binary search, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Lucky Tickets
Medium6
Brute force, Recursion+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Food Supplies for the Expedition
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Survival and Chocolate
Medium6
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Setting Cutlery
Medium6
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Magical Regular Bracket Sequence
Medium6
Backtracking, Recursion+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Jedi Calculations
Medium6
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Spy Jenga
Medium6
Game theory, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Spy Network Plan
Medium6
Geometry, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dnevnegrecheskaya Machine
Medium6
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Mysterious Ritual
Medium6
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candy in the Maze
Medium6
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dance Pairs
Medium6
Sorting, Stack+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Passwords
Medium6
String, String matching+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Nifflers at the Ministry
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
One Pair for Each Creature
Medium6
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Attacking Pairs
Medium6
Sliding window, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Secret of the Dragon Eye
Medium6
String, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Decoding the Message
Medium6
Combinatorics, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Harry and the Socks
Medium6
Combinatorics, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Towers
Medium6
Geometry, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Morty and the Password
Medium6
Greedy, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Morty and Subsequences
Medium6
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Save the Earth
Medium6
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Number Game
Medium6
Number theory, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Thor's Training
Medium6
Union-find, Matrix
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Suspicious String
Medium6
String, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Noise
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Safe password
Medium6
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Transaction Stability
Medium6
Sorting, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cave Paintings
Medium6
String, String matching
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pearls and the converter
Medium6
Greedy, Sliding window+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
New Fountain
Medium6
Heap, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Counting Events
Medium6
Bit manipulation, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Schedule
Medium6
Bit manipulation, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dipper's Gift
Medium6
Shortest path, Number theory+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
The Secret Room
Medium6
Dynamic programming, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Right-Side Interference
Medium6
Simulation, Queue+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Series
Medium6
Dynamic programming, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Typing Troubles
Medium6
Dynamic programming, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Knowledge is power
Medium6
Dynamic programming, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Vzryvopotam
Medium6
Stack, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
New Suitcase
Medium6
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cracking the Safe
Medium6
Dynamic programming, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Catching the Joker
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Professor's Experiment
Medium6
Dynamic programming, Simulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rangers on the Bus
Medium6
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cordon
Medium6
Greedy, Matrix+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Exam at British Intelligence
Medium6
String matching, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Long Journey
Medium6
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
McQueen's Nut Payment
Medium6
Bit manipulation, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
IPvK
Medium6
Dynamic programming, Math
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Watch the Marathon
Medium6
Number theory, Geometry
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Igrek and the Bracket Tree
Medium6
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sequence
Medium6
Bit manipulation, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Halloween
Medium6
Graph, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Competition
Medium6
Implementation, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Districts
Medium6
Dynamic programming, Bit manipulation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Teleports
Medium6
Sorting, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Game During the Break
Medium6
Bit manipulation, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sorting
Medium6
Segment tree, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Building the Fence
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Even More Secure PrisonPressing a segment rotates the disk by its value and removes that segment. Find the press that leaves the lexicographically smallest remaining sequence.	Medium6	ArrayGreedy	No attempts yet	1s	1024 MB	Judgeable
Painting a TreeGiven a tree, set every node on a path to the update index and answer queries for a single node's current value.	Medium6	TreeSegment tree	No attempts yet	2s	1024 MB	Judgeable
Explosive StaircaseGiven n levels where level i has i blocks, reorder the levels so that after blocks fall by gravity, the bottom level is lexicographically smallest.	Medium6	GreedyArray	No attempts yet	1s	1024 MB	Judgeable
Palindrome CipherFor each string t, decide whether t concatenated with some s_j is a palindrome, given n strings s_j of length up to 1000 and up to 10^6 strings t.	Medium6	String matchingHash map+1	No attempts yet	1s	1024 MB	Judgeable
We Need More EnergyCount the sequences of n values, each from 1 to x, that have exactly k interior strict peaks, modulo 1000000007.	Medium6	Dynamic programmingPrefix sum	No attempts yet	1s	1024 MB	Judgeable
Final ConfrontationCount the consecutive wave groups whose segment intersection length is between m1 and m2 inclusive.	Medium6	Two pointersSliding window+1	No attempts yet	1s	1024 MB	Judgeable
Become StrongerGiven n component times, find the fewest stack devices needed so every component fits one device under the spacing rules.	Medium6	SortingHash map+1	No attempts yet	1s	1024 MB	Judgeable
Robot ProductionGiven resource costs for n machines, pair them so the total saving, floor((a_i+a_j)/100) per pair plus single savings, is maximized, using the fewest pairs.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
In Pursuit of the PenguinCount the nonnegative integer points (x, y) with ax + by at most f, for each of t universes with values up to 1e9.	Medium6	MathNumber theory	No attempts yet	1s	1024 MB	Judgeable
Unusual TrapGiven a weighted tree and groups of people moving between rooms with elevator capacity b, find the minimum total durability the elevator loses.	Medium6	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
Smeshariki Gathering TimeFind the minimum seconds for n people on an integer grid to meet at one lattice point, moving up, down, left, right, or staying put each second.	Medium6	MathGreedy	No attempts yet	2s	1024 MB	Judgeable
Ramsey TheoryGiven a graph, find a clique of size l or an anticlique of size k, or report that neither exists.	Medium6	GraphBacktracking+1	No attempts yet	2s	1024 MB	Judgeable
Pyramid SearchAfter each point update, report the length of the longest contiguous segment that strictly rises and then strictly falls.	Medium6	Segment treeArray+1	No attempts yet	2s	1024 MB	Judgeable
Day OffGiven a die whose top-face value is added to a running sum s after each roll, decide for each query q whether s can equal q.	Medium6	SimulationMath+1	No attempts yet	2s	1024 MB	Judgeable
BridgesGiven a connected graph, find the fewest extra edges needed so that no edge is a bridge anymore.	Medium6	GraphDFS+1	No attempts yet	2s	1024 MB	Judgeable
Work From HomeGiven n classes (in-person or online), the day length d, and travel time t, find the maximum time Sid can spend at home.	Medium6	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
Acorn StringScrat starts on a letter grid and must collect nuts spelling a given string in order, minimizing the total number of moves.	Medium6	Dynamic programmingMatrix	No attempts yet	2s	1024 MB	Judgeable
GeysersCount right isosceles triangles with legs parallel to the axes whose sides contain no geysers other than the three vertices.	Medium6	SortingGeometry+1	No attempts yet	2s	1024 MB	Judgeable
CandyFind the fewest adjacent swaps needed to make the first F boxes hold at least T candy in total, or report NO if that is impossible.	Medium6	Dynamic programmingArray	No attempts yet	3s	1024 MB	Judgeable
The Tragedy of the Decreasing Growth Rate 1Given recorded daily growth values, decide whether true heights rounded to 0.001 cm can have a nonincreasing daily growth.	Medium6	GreedyMath+1	No attempts yet	1s	1024 MB	Judgeable
Defend Jaewoo's Pass!Given a 10-frame bowling scoreboard with some throws hidden, count the completions that give each total score from 0 to 220.	Medium6	Dynamic programmingImplementation	No attempts yet	1s	1024 MB	Judgeable
Building the Robot Convergence HallGiven N columns and M floors, decide whether Minjae should move first or second to force a fully blue row or column in a block-placing game.	Medium6	Game theoryMath	No attempts yet	2s	1024 MB	Judgeable
Jaewoo's Card GambleGiven N pairs of shuffled face-down cards, find the expected number of picks needed to collect all 2N cards under optimal play, modulo 1e9+7.	Medium6	Dynamic programmingProbability	No attempts yet	1s	1024 MB	Judgeable
Sum=ProductCount the contiguous subarrays whose element sum equals their element product, for N up to 300,000 and each A_i up to 300,000.	Medium6	MathBrute force+1	No attempts yet	1s	1024 MB	Judgeable
RLE Inversion CountingGiven M blocks, each repeated K times and appended to one array, count pairs i < j with A_i > A_j, modulo 1,000,000,007.	Medium6	SortingSegment tree+1	No attempts yet	3s	1024 MB	Judgeable
GibonniGiven up to six tiles with a notch in the top row, find the largest rectangle area that a subset of them can tile without gaps, with rotations allowed.	Medium6	BacktrackingBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Tricolor FlagEach column is split into red, white, and blue bands of at least one cell each, and the task is to maximize the total preference over all columns.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	4s	1024 MB	Judgeable
SquirrelsGiven a weighted graph, find the minimum spanning tree cost, then for each query report the new MST cost after one edge's weight is changed.	Medium6	Minimum spanning treeTree+1	No attempts yet	2s	1024 MB	Judgeable
Wooden LockGiven a tree whose vertices are white or black, find the minimum number of recolor and destroy operations needed to remove every vertex.	Medium6	TreeBFS	No attempts yet	2s	1024 MB	Judgeable
DiamondsCount the diamonds, which are pairs of triangles sharing an edge, in an undirected graph with up to 300000 vertices and edges.	Medium6	GraphCombinatorics	No attempts yet	2s	1024 MB	Judgeable
Crazy DanceGiven base a and target digit counts b_i, find the second at which the spoken digits first match every b_i exactly, or report -1 if it never happens.	Medium6	MathBinary search	No attempts yet	2s	1024 MB	Judgeable
Arithmetic and DiceGiven n dice with digits 0 to 9 on their faces, find the smallest natural number that cannot be built, where dice are reusable across numbers.	Medium6	GraphGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Tennis ScoreGiven the final score a:b, find the minimum possible sum of gcd values over every score visited on a path from 0:0 to a:b.	Medium6	Number theoryGreedy	No attempts yet	2s	1024 MB	Judgeable
Trouble with the TokenFind the lexicographically smallest length-k string reachable from s by repeatedly deleting the 1st, 2nd, second-to-last, or last character.	Medium6	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Shifting Boxes and a Caesar CipherFind a cyclic shift k and a Caesar shift d that turn string s into string t, or report that no such pair exists.	Medium6	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Road ConstructionTwo players alternately build rectangles of area at most s on an n by m grid, and the task asks whether the first player wins.	Medium6	MathGame theory	No attempts yet	2s	1024 MB	Judgeable
Repairing an ArrayGiven an array, find the fewest moves of single elements to the front or back needed to sort it.	Medium6	ArraySorting+1	No attempts yet	2s	1024 MB	Judgeable
Code LockGiven an n by n grid of empty cells, central elements, and handles, orient each handle vertically or horizontally so every handle reaches a central element through same-oriented handles, or report that it is impossible.	Medium6	GraphDFS+1	No attempts yet	2s	1024 MB	Judgeable
Bulk PurchasePick exactly m weapons using at least k distinct kinds to maximize total power, then minimize the largest count of any single kind.	Medium6	Binary searchSorting+1	No attempts yet	2s	1024 MB	Judgeable
Lucky TicketsFor each 6-digit ticket number, insert operators and parentheses between the digits to build an expression equal to 100, or report that none exists.	Medium6	Brute forceRecursion+2	No attempts yet	10s	1024 MB	Judgeable
Food Supplies for the ExpeditionPick the largest set of food types that can be fully eaten by their deadlines when c members eat c portions per day.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Survival and ChocolateGiven an n x m chocolate bar, find the largest perimeter reachable by repeatedly cutting it into two rectangles with an equal side and regluing them.	Medium6	MathNumber theory	No attempts yet	2s	1024 MB	Judgeable
Setting CutleryTwo waiters start at seats a and b on a round table of n seats; find the minimum time to place cutlery on every seat.	Medium6	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Magical Regular Bracket SequenceGiven n bracket pairs with inner distances a_i, the task is to build a correct bracket sequence where each pair has exactly a_i characters between its brackets, or report No.	Medium6	BacktrackingRecursion+1	No attempts yet	2s	1024 MB	Judgeable
Jedi CalculationsGiven an expression of non-negative numbers joined by + and -, delete exactly one character to make the resulting value as large as possible.	Medium6	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Spy JengaGiven a Jenga tower of n levels, decide who wins when Johnny moves first and the player whose move topples the tower loses.	Medium6	Game theoryMath	No attempts yet	2s	1024 MB	Judgeable
Spy Network PlanSplit the points into two groups whose convex hulls intersect, with the smaller group as small as possible, and print the indices of that smaller group.	Medium6	GeometrySorting	No attempts yet	2s	1024 MB	Judgeable
Dnevnegrecheskaya MachineGiven A liters of fuel at the temple, a 1-liter tank, and 100 km per liter, find the farthest one-way distance when fuel can be cached along the route.	Medium6	MathGreedy	No attempts yet	2s	1024 MB	Judgeable
The Mysterious RitualGiven n, repeatedly add its lowest digit until n is divisible by 10, then divide by 10. Find the smallest value n ever takes.	Medium6	MathImplementation	No attempts yet	2s	1024 MB	Judgeable
Candy in the MazeFind the longest lollipop that Ralph can carry from the left column to the right column through a grid maze with walls.	Medium6	GraphUnion-find+1	No attempts yet	2s	1024 MB	Judgeable
Dance PairsPair n boys and n girls on a number line so that no boy and girl both like each other more than their current partners, or report -1 if impossible.	Medium6	SortingStack+1	No attempts yet	2s	1024 MB	Judgeable
PasswordsCount the ways to split s into three nonempty parts a, b, c so that a+b, b+c, and a+c are pairwise distinct.	Medium6	StringString matching+1	No attempts yet	2s	1024 MB	Judgeable
Nifflers at the MinistryGiven each Niffler's height and target floor, find the minimum total number of floors walked by stairs when the elevator can only move upward.	Medium6	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
One Pair for Each CreatureCount the ways to pair n males on the x-axis with n females on the y-axis so that no two connecting segments cross, modulo 998244353.	Medium6	CombinatoricsMath	No attempts yet	2s	1024 MB	Judgeable
Attacking PairsGiven n strengths, find any pair of creatures within index distance k whose strength difference lies in [l, r], or report -1 -1 if none exists.	Medium6	Sliding windowBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Secret of the Dragon EyeGiven a binary string, find two different equal-length substrings with the same number of 1s, where the length is as large as possible, and print their endpoints.	Medium6	StringHash map+1	No attempts yet	2s	1024 MB	Judgeable
Decoding the MessageCount the distinct letter strings that encode to the given digit string for some unknown digit d from 0 to 9, modulo 1e9+7.	Medium6	CombinatoricsBit manipulation+1	No attempts yet	2s	1024 MB	Judgeable
Harry and the SocksCount the ways to pair each left sock with a right sock so that no pair has matching colors, modulo 10^9 + 7.	Medium6	CombinatoricsDynamic programming	No attempts yet	2s	1024 MB	Judgeable
TowersGiven a grid of towers, print the smallest connected, row- and column-convex set of cells that contains all of them.	Medium6	GeometryImplementation	No attempts yet	2s	1024 MB	Judgeable
Morty and the PasswordGiven a permutation where each cup can be touched at most twice by adjacent swaps, output the lexicographically largest permutation reachable.	Medium6	GreedyArray	No attempts yet	2s	1024 MB	Judgeable
Morty and SubsequencesFor each k from 1 to n, find the most elements that can be kept so the rest splits into contiguous strictly increasing blocks of length at least k.	Medium6	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
Save the EarthFind the shortest walk from a house to a point within r1 of antenna 1 and within r2 of antenna 2, given the antennas are farther apart than r1 + r2.	Medium6	GeometryMath+1	No attempts yet	2s	1024 MB	Judgeable
Number GameGiven a and b, find the fewest seconds to reach 2^60-1 from 0 by adding values in [a, b] modulo 2^61, or -1 if impossible.	Medium6	Number theoryMath	No attempts yet	2s	1024 MB	Judgeable
Thor's TrainingGiven an n by m grid and q rectangle outlines struck in order, report how many connected unhit regions remain after each strike.	Medium6	Union-findMatrix	No attempts yet	2s	1024 MB	Judgeable
Suspicious StringGiven a lowercase string, decide whether its letters can be rearranged into a palindrome where each letter moves at most one position.	Medium6	StringDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
NoiseGiven noisy values and a noise bound R, find the most distinct values the original sequence could have, plus one valid original sequence.	Medium6	GreedySorting+1	No attempts yet	2s	1024 MB	Judgeable
Safe passwordChange the fewest characters so the string has no three equal letters in a row and no letter occupies more than half its positions.	Medium6	StringGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Transaction StabilitySplit some of the n transactions once each to maximize the ratio of the smallest final amount to the largest, given amounts up to 10^4.	Medium6	SortingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Cave PaintingsGiven a string s, find the length of the longest palindrome that is a substring of some cyclic shift of s.	Medium6	StringString matching	No attempts yet	1s	1024 MB	Judgeable
Pearls and the converterGiven n pearls with colors from 1 to k, form the most sets of k pairwise-distinct colors where any two pearls in a set are at most m seconds apart.	Medium6	GreedySliding window+1	No attempts yet	2s	1024 MB	Judgeable
New FountainGiven an n by m grid of pillar heights, find the maximum total volume of water the grid can hold without draining off the border.	Medium6	HeapBFS+1	No attempts yet	2s	1024 MB	Judgeable
Counting EventsGiven n numbers and q queries, decide for each query whether it can be built from the numbers by repeatedly applying bitwise OR and AND.	Medium6	Bit manipulationMath	No attempts yet	2s	1024 MB	Judgeable
ScheduleGiven a day i and a moment j for up to 1e5 queries (each up to 1e9), print the task number Katie does at that day and moment.	Medium6	Bit manipulationMath	No attempts yet	2s	1024 MB	Judgeable
Dipper's GiftGiven a string and letter-replacement costs, find the minimum cost to make the string a k-string for some k greater than 1, or report -1 if impossible.	Medium6	Shortest pathNumber theory+1	No attempts yet	2s	1024 MB	Judgeable
The Secret RoomGiven a sequence, find the length of the longest subsequence where every pair satisfies a_i - a_j < j - i.	Medium6	Dynamic programmingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Right-Side InterferenceGiven cars arriving at four sides of a crossroad, output the second each car crosses, where a car must wait while a car queues on its right.	Medium6	SimulationQueue+1	No attempts yet	1s	1024 MB	Judgeable
SeriesGiven n episode sizes and a fixed per-packet header k, find the minimum total packet size when one shared request sequence must download every episode.	Medium6	Dynamic programmingSorting	No attempts yet	1s	1024 MB	Judgeable
Typing TroublesGiven strings s and t of length n up to 5000, decide whether t can be formed by splitting s into blocks and placing each block at the front of the typed text.	Medium6	Dynamic programmingString matching+1	No attempts yet	1s	1024 MB	Judgeable
Knowledge is powerGiven n starting carriers and k days, count all carriers that appear, where a level i carrier makes i new ones each day, modulo 1e9+7.	Medium6	Dynamic programmingMath	No attempts yet	2s	1024 MB	Judgeable
VzryvopotamAfter one cyclic shift of the heights, find the longest chain of posts broken by jumping to the nearest strictly taller post on the right.	Medium6	StackDynamic programming	No attempts yet	2s	1024 MB	Judgeable
New SuitcaseGiven n, find the largest total length of sticks 1 to n that can form the sides of a rectangle, or 0 if none can.	Medium6	MathGreedy	No attempts yet	2s	1024 MB	Judgeable
Cracking the SafeCount the integers in [l, r], given as decimal strings up to 10^5 digits long, whose digits form an arithmetic progression modulo 10.	Medium6	Dynamic programmingString	No attempts yet	2s	1024 MB	Judgeable
Catching the JokerGiven a tree and m paths, find the vertex from which the most paths can be walked as one simple route through every vertex on the path.	Medium6	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
Professor's ExperimentGiven start and end flasks of n bacteria and q moves among three flasks, decide whether some choice of moving bacteria matches the records.	Medium6	Dynamic programmingSimulation	No attempts yet	2s	1024 MB	Judgeable
Rangers on the BusGiven the seats k passengers took in boarding order, find which passengers could be each of the five ranger types.	Medium6	SortingGreedy+1	No attempts yet	2s	1024 MB	Judgeable
CordonBlock the fewest cells in an n x m grid so that every right-or-down path from the top-left to the bottom-right passes through at least k blocked cells.	Medium6	GreedyMatrix+1	No attempts yet	2s	1024 MB	Judgeable
Exam at British IntelligenceGiven a string s, find every k such that s splits into k equal-length pieces that are all cyclic shifts of each other.	Medium6	String matchingString+1	No attempts yet	2s	1024 MB	Judgeable
Long JourneyGiven k and a number x with up to 10^6 digits, find the smallest y at least x that uses at most k distinct digits and has no leading zeros.	Medium6	GreedyString+1	No attempts yet	2s	1024 MB	Judgeable
McQueen's Nut PaymentGiven a price range [a_i, b_i] for each of n items, find the minimum total of power-of-two nut coins that can pay any possible total price.	Medium6	Bit manipulationMath+1	No attempts yet	2s	1024 MB	Judgeable
IPvKGiven K candidates and N voters, sum the products of vote counts over all K-tuples of counts from 0 to 255 that total N, modulo 998244353.	Medium6	Dynamic programmingMath	No attempts yet	8s	1024 MB	Judgeable
Watch the MarathonGiven a segment from the origin to (a, b), find the integer lattice point off the segment closest to it, breaking ties by smallest X, then smallest Y.	Medium6	Number theoryGeometry	No attempts yet	8s	1024 MB	Judgeable
Igrek and the Bracket TreeCount ordered bracket trees whose postorder bracket string is a correct sequence with n opening brackets, modulo 1e9+7.	Medium6	CombinatoricsMath+1	No attempts yet	2s	1024 MB	Judgeable
SequenceGiven a sequence of k-bit integers, handle point updates and answer queries for f(l, r), a chain of negated ANDs over a range.	Medium6	Bit manipulationArray+1	No attempts yet	2s	1024 MB	Judgeable
HalloweenGiven a graph, erase at most half of each vertex's edges so that the remaining graph is bipartite, and print the erased edge numbers.	Medium6	GraphGreedy+1	No attempts yet	2s	1024 MB	Judgeable
CompetitionGiven n participants and k disciplines, construct scores from 0 to 10 so each participant beats the previous one in more than half of the disciplines and loses to the next one.	Medium6	ImplementationMath	No attempts yet	2s	1024 MB	Judgeable
DistrictsAssign n participants to the fewest districts so that no given triple of participants lies entirely in one district.	Medium6	Dynamic programmingBit manipulation	No attempts yet	2s	1024 MB	Judgeable
TeleportsGiven a circle with teleports that switch on and off, print the longest shortest travel time between any two points after each change.	Medium6	SortingImplementation+1	No attempts yet	2s	1024 MB	Judgeable
Game During the BreakGiven n numbers, split even numbers into equal halves and merge equal pairs by their sum; find the largest number that can be produced.	Medium6	Bit manipulationGreedy+1	No attempts yet	2s	1024 MB	Judgeable
SortingGiven a permutation, process Q queries that sort a range ascending or descending or return a range sum, then print the final array.	Medium6	Segment treeSorting+1	No attempts yet	2s	1024 MB	Judgeable
Building the FenceCount the subsets of boards that can form a polygon with nonzero area, meaning the longest board is shorter than the sum of the rest, modulo 1e9+7.	Medium6	Dynamic programmingSorting+1	No attempts yet	2s	1024 MB	Judgeable