Problems

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Total results29,414 problems

Kilk
Medium6
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alternative Accounts
Medium6
Bit manipulation, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Evil Subsequence
Medium6
Dynamic programming, Hash map
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Assistant Lab Assignment
Medium6
Graph, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Team Assignment
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
0.7s
Memory limit
256 MB
Judgeable
Equilateral Triangles
Medium6
Math, Hash map+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Triangles (Silver)
Medium6
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Clock Tree
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Swapity Swap
Medium6
Simulation, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Multiple of N (1)
Medium6
Combinatorics, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Alternative Facts
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Amazing Sushi
Medium6
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bubble Bucket Sort
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cartography
Medium6
Graph, Implementation+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Heroic Heist
Medium6
Graph, Greedy+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Hyper Array and Hyper Queries
Medium6
Prefix sum, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Solving Problems
Medium6
Implementation, Queue+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Problem Solving Problem (Juryeonggu)
Medium6
Simulation, String+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Problem About Solving Problems (Dequery)
Medium6
Linked list, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Legendary Dango Maker 1
Medium6
Matrix, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Legendary Dango Maker 2
Medium6
Greedy, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Day of Going to the Training Camp
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bowing to Parents
Medium6
Sorting, Implementation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
A Friend's Face and One Blade of Grass
Medium6
Graph, Dynamic programming+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Social Distancing I
Medium6
Greedy, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
New Year and Ascent Sequence
Medium6
Sorting, Binary search+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Autumn Cleaning (16 MiB ML!)
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
16 MB
Judgeable
Intersection of Parabolas
Medium6
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Jaw-Dropping Set
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximum Multiple
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Triangle Partition
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Distinct Values
Medium6
Greedy, Intervals+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Keyboard
Medium6
String, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Readability
Medium6
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Wrestling Competition
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Numb
Medium6
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Admiral
Medium6
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jacana Numbers
Medium6
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Master Zhu and Chessboard
Medium6
Dynamic programming, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Master Zhu and Video
Medium6
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Intervals
Medium6
Intervals, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Copying Homework
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Klothes
Medium6
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Arithmetic Sequences
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Chocolate is Tasty
Medium6
Simulation, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lines
Medium6
Graph, Hash map+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Balls of Buma
Medium6
String, Implementation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Palindromic Dates
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flat Earth
Medium6
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Stairways
Medium6
Dynamic programming, Prefix sum
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Forever and Always
Medium6
Simulation, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Median
Medium6
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Three Arrays
Medium6
Two pointers, Sorting+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Elevator
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Subsequence Sum Queries
Medium6
Divide and conquer, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Octagons
Medium6
String, Stack+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Statistics
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
1.5s
Memory limit
256 MB
Judgeable
Zigzag
Medium6
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Education Nightmare
Medium6
Tree, DFS+1
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Bit Operations
Medium6
Bit manipulation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Frogs
Medium6
Greedy, Implementation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Keep Distance
Medium6
String, Brute force+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Split Game
Medium6
Geometry, Sorting
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Eureka
Medium6
Geometry, Sorting+1
No attempts yet
Time limit
5s
Memory limit
64 MB
Judgeable
Cocktails
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Unrumpf
Medium6
Geometry, Probability+1
No attempts yet
Time limit
5s
Memory limit
256 MB
Judgeable
K-transform
Medium6
Matrix, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Math is Fun
Medium6
Number theory, Dynamic programming
No attempts yet
Time limit
4s
Memory limit
256 MB
Judgeable
House Moving
Medium6
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Travel in Sugar Country
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Battle simulation
Medium6
Shortest path, Simulation+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Light Warrior Cripure
Medium6
Greedy, Intervals+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Subarray Average of a Sequence
Medium6
Prefix sum, Hash map+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Divisor
Medium6
Sorting, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hotel Room Assignment
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Card Shuffle
Medium6
Tree, Simulation
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Unique Calculator
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Supercomputer
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Binary Ternary Search Play 1
Medium6
Divide and conquer, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Surmising a Sprinter's Speed
Medium6
Sorting, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Meeting Room Scheduling 2
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Meeting Room Scheduling 3
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Marshmallow Molecules
Medium6
Graph, Union-find+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Centi and the Magic Hammer
Medium6
Heap, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Battle Royale
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Restroom Rules
Medium6
Simulation, Heap+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Nested Set Model
Medium6
DFS, Tree+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
TORIE
Medium6
Tree, String matching+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Zombies even at the machine gun nest
Medium6
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Passing On a Good Deed
Medium6
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Visiting Singapore
Medium6
Dynamic programming, String matching
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Cryptography
Medium6
Combinatorics, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shuffle
Medium6
Array, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Collecting Mushrooms
Medium6
Prefix sum, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Journey
Medium6
Dynamic programming, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Lightning Rod
Medium6
Stack, Greedy+1
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable
Snail
Medium6
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Class
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fabric
Medium6
Stack, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Unlucky Floors
Medium6
Math, Binary search+2
No attempts yet
Time limit
2.5s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
KilkCount the strings with x letters a and y letters b whose longest run of equal letters is as small as possible, modulo 998244353.	Medium6	CombinatoricsMath+1	No attempts yet	2s	512 MB	Judgeable
Alternative AccountsGiven up to 4 contests and the accounts in each, find the fewest people who can own all accounts, where two accounts in the same contest need different owners.	Medium6	Bit manipulationGraph+1	No attempts yet	2s	512 MB	Judgeable
Evil SubsequenceCount the subsequences of a whose equal-and-different pattern matches b exactly, so positions i and j hold equal values in the subsequence precisely when b_i equals b_j.	Medium6	Dynamic programmingHash map	No attempts yet	3s	512 MB	Judgeable
Assistant Lab AssignmentAssign people to three labs, each with a capacity, respecting each person's single lab preference, and maximize the number assigned.	Medium6	GraphGreedy+2	No attempts yet	1s	256 MB	Judgeable
Team AssignmentAssign each participant to team A (scoring their attack) or team B (scoring their defense) so the team sizes differ by at most k, maximizing the total.	Medium6	GreedySorting+2	No attempts yet	0.7s	256 MB	Judgeable
Equilateral TrianglesGiven an N by N grid of cows, count triples of cows that are pairwise equidistant under Manhattan distance, with N up to 300.	Medium6	MathHash map+1	No attempts yet	2s	512 MB	Judgeable
Triangles (Silver)Given N points, sum twice the areas of all right triangles whose legs are parallel to the axes, modulo 1e9+7.	Medium6	MathGeometry+2	No attempts yet	1s	512 MB	Judgeable
Clock TreeCount the starting rooms in a tree from which a walk can leave every clock pointing at 12, where each entry advances that room's clock by one.	Medium6	TreeDFS+1	No attempts yet	2s	512 MB	Judgeable
Swapity SwapStarting from cows labeled 1 to N in order, apply a fixed pair of range reversals K times and report the final order.	Medium6	SimulationMath+2	No attempts yet	2s	512 MB	Judgeable
Multiple of N (1)Given 2N-1 numbers, find N of them whose sum is divisible by N, or report that none exists.	Medium6	CombinatoricsPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Alternative FactsRearrange the array A into B so that the first L positions stay within K of the original values, making B lexicographically largest.	Medium6	GreedySorting+1	No attempts yet	1.5s	256 MB	Judgeable
Amazing SushiGiven counts of n sushi types and an allowed piece range for each person, decide whether every piece can be split so each type is shared evenly (one extra allowed) and both stay in range.	Medium6	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
Bubble Bucket SortPartition n bubble sizes into at most b buckets to minimize the sum of squared differences between the largest and smallest size in each bucket.	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	512 MB	Judgeable
CartographyGiven possibly wrong neighbour lists for each house in an unknown r by c grid, find a grid layout that matches all lists or report -1.	Medium6	GraphImplementation+1	No attempts yet	3s	512 MB	Judgeable
Heroic HeistRooms sit in a line, each door is locked or holds a key that opens a listed set of doors and is consumed once; start in room 1 and find the most rooms you can enter.	Medium6	GraphGreedy+1	No attempts yet	3s	512 MB	Judgeable
Hyper Array and Hyper QueriesGiven a value for every cell of an 11-dimensional array, answer range-sum queries over axis-aligned 11-dimensional boxes.	Medium6	Prefix sumArray+2	No attempts yet	2s	512 MB	Judgeable
Solving ProblemsFive separate problems (Dequery, 박승원, Mini Album, Juryeonggu, Incorrectly Implemented Euler Circuit) each read their own input and print one answer, in order.	Medium6	ImplementationQueue+2	No attempts yet	3s	512 MB	Judgeable
Problem Solving Problem (Juryeonggu)Given a start face and a command string with nested repeats up to 10^9, roll a die on the octa-hexahedron and print the face on the floor at the end.	Medium6	SimulationString+1	No attempts yet	1s	512 MB	Judgeable
Problem About Solving Problems (Dequery)Maintain a deque under queries that push the same value many times at either end, pop many elements, and read the k-th element; output each read.	Medium6	Linked listImplementation+2	No attempts yet	1s	512 MB	Judgeable
Legendary Dango Maker 1Given a grid of pink, white, and green dangos, maximize the number of sticks in pink-white-green or green-white-pink order, with each dango used once.	Medium6	MatrixGraph+1	No attempts yet	1s	512 MB	Judgeable
Legendary Dango Maker 2Find non-overlapping runs of three consecutive grid cells that read P-W-G or G-W-P, then mark each chosen run by its direction in the output grid.	Medium6	GreedyMatrix+1	No attempts yet	1s	512 MB	Judgeable
The Day of Going to the Training CampCount sequences of length N over values 1..M that avoid any local peak (a[i-1] < a[i] > a[i+1]), modulo 998244353.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Bowing to ParentsGiven N shuffled integers, decide whether they can be rearranged into a sequence that decreases by a constant step and then increases by a constant step.	Medium6	SortingImplementation+1	No attempts yet	2s	1024 MB	Judgeable
A Friend's Face and One Blade of GrassCount the command sequences that take Wookje from (1,1) to (N,M) without leaving the grid, or report -1 if there are infinitely many.	Medium6	GraphDynamic programming+1	No attempts yet	3s	1024 MB	Judgeable
Social Distancing IGiven a binary string of occupied and empty stalls, place two new cows in empty stalls so the minimum distance between any two occupied stalls is as large as possible, and print that distance.	Medium6	GreedyBinary search+2	No attempts yet	1s	512 MB	Judgeable
New Year and Ascent SequenceGiven n sequences, count ordered pairs whose concatenation contains an increasing pair, using each sequence's own ascent and its min and max values.	Medium6	SortingBinary search+2	No attempts yet	2s	1024 MB	Judgeable
Autumn Cleaning (16 MiB ML!)Count the k-element subsets of n item prices whose sum is divisible by r, modulo 10^6+3.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	2s	16 MB	Judgeable
Intersection of ParabolasFind the area of the region bounded by the parabolas y=(x-a)^2 and x=(y-a)^2, given a up to 10^18, printed to exactly 10 decimals.	Medium6	MathGeometry+2	No attempts yet	1s	256 MB	Judgeable
Jaw-Dropping SetFor each n up to 1e9, find the maximum size of a subset of {1..n} with no element dividing another, then the minimum possible sum among such maximum-size subsets.	Medium6	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Maximum MultipleFor each n, split it into three positive divisors x, y, z summing to n so that the product xyz is as large as possible, or report that no split exists.	Medium6	MathNumber theory+2	No attempts yet	2s	256 MB	Judgeable
Triangle PartitionGiven 3n points with no three collinear, partition all of them into n disjoint triangles and output the indices used by each triangle.	Medium6	GeometrySorting+2	No attempts yet	1s	256 MB	Judgeable
Distinct ValuesGiven n positive integers and m facts that each force a range l to r to hold distinct values, find the lexicographically smallest array satisfying all facts.	Medium6	GreedyIntervals+1	No attempts yet	2s	256 MB	Judgeable
KeyboardGiven the hacker's recorded string and a candidate password, decide whether the candidate could produce that recording under the caps-lock/backspace swap.	Medium6	StringTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
ReadabilityReorder n integers so odd and even values alternate, minimize the total moves \|i-j\|, and output the lexicographically smallest such order.	Medium6	SortingGreedy+1	No attempts yet	2s	256 MB	Judgeable
Wrestling CompetitionGiven strengths and a threshold K, count players who could be the last survivor when random pairings are played and a match is decided by strength unless the gap is at most K.	Medium6	SortingGreedy+2	No attempts yet	1s	512 MB	Judgeable
NumbBuild an n-digit binary string whose prefixes all leave distinct remainders mod n and whose whole value is divisible by n.	Medium6	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
AdmiralFind the fewest swaps of the flagship (0) with an adjacent battleship needed to place every kind in its own row, or report that more than 20 swaps are required.	Medium6	GraphBFS+1	No attempts yet	1s	512 MB	Judgeable
Jacana NumbersGiven two power towers J(n, a) and J(m, b), print whether the first is greater than, equal to, or less than the second for each test case.	Medium6	MathImplementation	No attempts yet	1s	512 MB	Judgeable
Master Zhu and ChessboardGiven a board where each row has a black interval with monotone endpoints, find the fewest pieces on black squares so every black square shares a row or column with a piece.	Medium6	Dynamic programmingTwo pointers+1	No attempts yet	1s	512 MB	Judgeable
Master Zhu and VideoGiven volume p and target q, find the fewest seconds to reach q using Up (+1 dB) and Down orders, where each consecutive Down doubles its drop.	Medium6	MathGreedy+1	No attempts yet	1s	512 MB	Judgeable
IntervalsGiven an n by n matrix of pairwise intersection lengths, decide whether some set of n intervals, all of length 10^6, can produce exactly that matrix.	Medium6	IntervalsGreedy+1	No attempts yet	1s	512 MB	Judgeable
Copying HomeworkGiven a permutation A of 1..N, output any permutation B of 1..N whose sum of absolute differences from A is at least N.	Medium6	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
KlothesGiven n, s, k, decide whether k distinct prices from 1 to n can sum to s, and if so print one such subset as a bit string.	Medium6	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
Arithmetic SequencesGiven a set of distinct integers, find the size of the largest subset that can be ordered as an arithmetic sequence.	Medium6	Dynamic programmingSorting+2	No attempts yet	1.5s	512 MB	Judgeable
Chocolate is TastyGiven a circle of boys (B) and girls (G) and an n by m chocolate bar, find the starting child who lets the most distinct children eat a piece.	Medium6	SimulationString+1	No attempts yet	2s	512 MB	Judgeable
LinesSelect the largest set of lines so that no two are identical, parallel, or meet at the same point on the line x = 0.	Medium6	GraphHash map+1	No attempts yet	1s	256 MB	Judgeable
Balls of BumaGiven a row of colored balls, count the color and insertion position pairs that make the chain reaction remove every ball.	Medium6	StringImplementation+2	No attempts yet	3s	512 MB	Judgeable
Palindromic DatesFor each given date, find the next strictly later date that reads the same forwards and backwards ignoring the dots, accounting for leap years.	Medium6	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Flat EarthGiven a sphere and a plane, compute the area of the sphere's orthogonal projection onto the plane.	Medium6	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
StairwaysSplit n people into two stairways in entry order so that each person's arrival is the running maximum on their stairway, minimizing total delay.	Medium6	Dynamic programmingPrefix sum	No attempts yet	2s	512 MB	Judgeable
Forever and AlwaysBuild preference lists for a repeated voting process so that at least p iterations run before no one changes their vote.	Medium6	SimulationImplementation	No attempts yet	2s	512 MB	Judgeable
MedianGiven a sequence, find the lexicographically largest permutation in which the median of every prefix is non-decreasing.	Medium6	GreedySorting	No attempts yet	2s	256 MB	Judgeable
Three ArraysGiven three sorted arrays and a distance d, count triples of elements (one from each array) whose pairwise differences all stay within d.	Medium6	Two pointersSorting+2	No attempts yet	2s	256 MB	Judgeable
ElevatorGiven passenger arrival times and destination floors, choose when to dispatch the elevator to minimize the time it finally returns to floor 0.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Subsequence Sum QueriesFor each query range [l, r] of an array with m at most 20, count the subsequences whose sum is divisible by m, modulo 1e9+7.	Medium6	Divide and conquerDynamic programming	No attempts yet	2s	256 MB	Judgeable
OctagonsGiven a string of edge labels a, b, c walked on an octagon tessellation graph, decide whether the walk returns to its starting vertex.	Medium6	StringStack+1	No attempts yet	1s	256 MB	Judgeable
StatisticsPick the fewest courses whose units sum to exactly V, then find the minimum average, median, highest repeat count, and max-min range over those schedules.	Medium6	Dynamic programmingSorting+1	No attempts yet	1.5s	256 MB	Judgeable
ZigzagFind the longest sequence that is a subsequence of both given arrays and whose consecutive triples strictly alternate up and down.	Medium6	Dynamic programmingArray	No attempts yet	2s	256 MB	Judgeable
Education NightmareOn a tree of n rooms, find the minimum worst-case time to reach the class from room s, where entering room m reveals the class location.	Medium6	TreeDFS+1	No attempts yet	10s	512 MB	Judgeable
Bit OperationsGiven N pairs of 8-bit inputs and outputs, build a C expression using x, constants, ~, &, \|, ^, +, -, and * that maps each x_i to y_i.	Medium6	Bit manipulationBrute force+1	No attempts yet	1s	512 MB	Judgeable
FrogsGiven how many frogs cross each gap between adjacent rocks, build a frog permutation that produces exactly those counts, or report that none exists.	Medium6	GreedyImplementation+1	No attempts yet	1s	256 MB	Judgeable
Keep DistanceGiven a row of colored cubes, find for each color the fewest swaps needed to place all cubes of that color at equal spacing.	Medium6	StringBrute force+2	No attempts yet	3s	512 MB	Judgeable
Split GameGiven a simple polygon in counter-clockwise order, find the largest number of nonzero-area regions that one line through the origin can create.	Medium6	GeometrySorting	No attempts yet	1s	512 MB	Judgeable
EurekaCount the subsets of n labeled points that contain a pair whose segment covers every other chosen point, modulo 1e9+7.	Medium6	GeometrySorting+1	No attempts yet	5s	64 MB	Judgeable
CocktailsGiven n jars with hand-blending times a_i, a blender that mixes k consecutive jars for B, and swaps costing C, find the minimum total time to blend all jars.	Medium6	Dynamic programmingSorting+1	No attempts yet	2s	256 MB	Judgeable
UnrumpfGiven the convex hull of 10 to 100 random integer points, guess how many points generated each hull.	Medium6	GeometryProbability+1	No attempts yet	5s	256 MB	Judgeable
K-transformCount integers n that reach 1 after exactly m applications of f (divide by k if divisible, otherwise subtract 1), modulo a prime.	Medium6	MatrixDynamic programming+1	No attempts yet	2s	256 MB	Judgeable
Math is FunGiven an array A of up to 100 values in [1, 1000], sum GCD(S) * LCM(S)^2 over all subsets S of A, modulo 1000000007.	Medium6	Number theoryDynamic programming	No attempts yet	4s	256 MB	Judgeable
House MovingPlace M families of given sizes into distinct houses 1 to N to maximize the total distance between all pairs of residents across different families.	Medium6	Dynamic programmingSorting+1	No attempts yet	1s	256 MB	Judgeable
Travel in Sugar CountryCount ordered sequences of K distinct towns on a line whose total travel distance is divisible by M.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	1s	256 MB	Judgeable
Battle simulationSimulate dash commands on a grid where units stop when they meet an enemy and cannot exceed their movement power, then print final positions.	Medium6	Shortest pathSimulation+1	No attempts yet	2s	1024 MB	Judgeable
Light Warrior CripureFind the fewest rays from the circle's center that together hit every rubber band chord, where a ray hitting a post also counts.	Medium6	GreedyIntervals+1	No attempts yet	1s	1024 MB	Judgeable
Subarray Average of a SequenceCount the contiguous subarrays of a given sequence whose elements have an average exactly equal to K.	Medium6	Prefix sumHash map+2	No attempts yet	1s	256 MB	Judgeable
DivisorGiven up to 5000 positive integers, change the fewest of them to any positive integers so that every pair is in a divisor-multiple relationship.	Medium6	SortingDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Hotel Room AssignmentCount the ways to place any number of guests on N floors of two rooms each so that no two guests share a floor or sit vertically adjacent, modulo 1e9+7.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
Card ShuffleGiven a deck of N cards, apply Q queries that move a range to the top or bottom or ripple-shuffle it, then print the final order.	Medium6	TreeSimulation	No attempts yet	10s	1024 MB	Judgeable
Unique CalculatorEvaluate an arithmetic expression by repeatedly reducing the operator at either end with the highest precedence and largest result, following the stated tie-break rules.	Medium6	ImplementationSimulation+2	No attempts yet	1s	1024 MB	Judgeable
SupercomputerChoose an order of N programs and one program to shorten to 1 hour, minimizing the maximum lateness relative to deadlines.	Medium6	GreedySorting+2	No attempts yet	1s	256 MB	Judgeable
Binary Ternary Search Play 1For every index in a sorted array of size N, compare the number of probes binary search and ternary search need to reach it, and count how often binary wins, ties, and loses.	Medium6	Divide and conquerBinary search+2	No attempts yet	1s	256 MB	Judgeable
Surmising a Sprinter's SpeedGiven N observations of time and position on a line, find the largest speed the sprinter must have reached at some moment.	Medium6	SortingMath+2	No attempts yet	2s	512 MB	Judgeable
Meeting Room Scheduling 2Given N meetings that overlap only with their immediate neighbors in the list, choose a non-overlapping subset maximizing total attendees.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	256 MB	Judgeable
Meeting Room Scheduling 3Choose non-overlapping meetings, where each meeting's time overlaps only its immediate neighbors in the input order, to maximize the total attendee count.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	256 MB	Judgeable
Marshmallow MoleculesFind the fewest skewers needed to include every required pair, so that for any a<b<c with skewers a-b and a-c there is also a skewer b-c.	Medium6	GraphUnion-find+1	No attempts yet	4s	512 MB	Judgeable
Centi and the Magic HammerRepeatedly halve the current tallest giant (floor division, stopping at 1) up to T times; report whether every giant ends below Centi's height, with the minimum hammer uses or the final tallest height.	Medium6	HeapGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Battle RoyaleJunseok starts with M health, must defeat X opponents and eat Y items in an order that keeps his health above 0, or report that none exists.	Medium6	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Restroom RulesEmployees are dealt into M lines round-robin; repeatedly the head with the largest D, then largest H, then smallest line index is served. Count who goes before Deka.	Medium6	SimulationHeap+2	No attempts yet	1s	1024 MB	Judgeable
Nested Set ModelRoot an undirected tree at S, traverse children in ascending order, and label each node with nested left/right interval numbers.	Medium6	DFSTree+2	No attempts yet	1s	1024 MB	Judgeable
TORIEGiven nested bracket trees with uppercase labels, remove the fewest TORIEs when the keyword matches a label or a label extended into child labels, then print what remains.	Medium6	TreeString matching+1	No attempts yet	1s	1024 MB	Judgeable
Zombies even at the machine gun nestGiven zombie healths at each distance on a road, decide whether a machine gun and limited mines can stop every zombie before one reaches the nest's front.	Medium6	GreedySimulation	No attempts yet	1s	1024 MB	Judgeable
Passing On a Good DeedGiven a directed graph and a subject K, find the start X (not K) with the most people on some path from X to K, and print X and that count.	Medium6	GraphBFS+1	No attempts yet	1s	1024 MB	Judgeable
Visiting SingaporeChoose which days to attend so the events match T in order, paying penalties for skipped events and long idle gaps, to maximize total happiness.	Medium6	Dynamic programmingString matching	No attempts yet	2s	256 MB	Judgeable
CryptographyGiven a permutation P of N distinct integers, output the 1-based rank of P among all permutations of its values, modulo 1,000,000,007.	Medium6	CombinatoricsSorting+2	No attempts yet	1s	512 MB	Judgeable
ShuffleRecover the episode number on each CD by grouping CDs into boxes and asking for the set of episodes in each box, using at most Q queries.	Medium6	ArrayBit manipulation+1	No attempts yet	1s	512 MB	Judgeable
Collecting MushroomsGiven a grid with mushrooms and sprinklers, count mushrooms covered by at least K sprinklers within Chebyshev distance D.	Medium6	Prefix sumMatrix+2	No attempts yet	1s	512 MB	Judgeable
JourneyCount itineraries from city 0 to city n-1 that visit only strictly nearer cities, for each total night count below m, capping each count at 500000001.	Medium6	Dynamic programmingGraph+1	No attempts yet	1s	512 MB	Judgeable
Lightning RodGiven N buildings with tops at (X_i, Y_i), find the fewest buildings to place lightning rods on so that every building lies under a rod's 45-degree protection cone.	Medium6	StackGreedy+1	No attempts yet	2.5s	512 MB	Judgeable
SnailGiven a daily cycle of N moves that can climb or slide (never below 0), find the day and phase when the snail first reaches height H, or -1 -1 if it never does.	Medium6	MathSimulation+2	No attempts yet	1s	512 MB	Judgeable
ClassSplit N students of distinct heights into the fewest teams so that in every team, each student has fewer than k_i taller teammates.	Medium6	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
FabricCount the axis-aligned sub-rectangles of an N by M grid that contain no holes and have area at least K.	Medium6	StackMatrix+1	No attempts yet	1s	512 MB	Judgeable
Unlucky FloorsConvert floor numbers between a conventional scheme and one that skips any number containing the substrings 4 or 13, answering queries or reporting -1.	Medium6	MathBinary search+2	No attempts yet	2.5s	512 MB	Judgeable