Interview warm-up

Short whiteboard warmups

Under construction

Still being built. Things may change

Total results4,880 problems

Darts
Medium4
Prefix sum, Matrix
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rally
Medium4
Graph, Brute force
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Sieve Game
Medium4
Number theory, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mysterious words
Medium4
Dynamic programming, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Oak Tree Heights
Medium4
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Stubborn Little Frog
Medium4
Dynamic programming, Sliding window
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Lietus (Rain)
Medium4
Array, Two pointers
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Snake
Medium4
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Break a Prison
Medium4
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ducks and the Clapping Chunbae
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Museum Tour
Medium4
Prefix sum, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Chunbae Who Stole Nabi's Snack
Medium4
Dynamic programming, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rebirth
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jamboree
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Symmetry of Stars
Medium4
Hash map, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Group Jump Rope
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hanging a Banner
Medium4
Brute force, Binary search+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Switch
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fishing
Medium4
Prefix sum, Matrix
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
K-String
Medium4
Bit manipulation, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Why Hoban-woo Was Late to School 4
Medium4
Union-find, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Inversions
Medium4
Math, String+1
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Geometry Game
Medium4
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
SASA Manito
Medium4
Implementation, Graph
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hate Stagnant Water
Medium4
BFS, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Prof. Fumblemore and the Collatz Conjecture
Medium4
Brute force, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Klyukalo
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
First Solved, Last Coded
Medium4
Stack, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Alloys
Medium4
Sorting, Array
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Heavy Rainfall
Medium4
Array, Two pointers+1
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Variable Assignments
Medium4
Union-find
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Constructive
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dance Time
Medium4
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
March First
Medium4
BFS, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sorting the Strip
Medium4
Array, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Count of Maximum-Sum Same-Value Pairs
Medium4
Hash map, Prefix sum
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Labirint
Medium4
Bit manipulation, Union-find+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sum of Consecutive Primes
Medium4
Prefix sum, Math+1
No attempts yet
Time limit
0.7s
Memory limit
1024 MB
Judgeable
Trapping the Star
Medium4
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maze Repair
Medium4
Graph, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Unusual competitions
Medium4
String, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Watching TV Series
Medium4
Simulation, Binary search
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sowing Work
Medium4
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Maximum Sum with Equal Endpoints
Medium4
Hash map, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Gahee and Travel
Medium4
Minimum spanning tree, Sorting+1
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Fruit Tanghulu
Medium4
Sliding window, Hash map
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gunggong Punch Arithmetic Sequence
Medium4
Array, Greedy+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Magic Cards
Medium4
Hash map, Bit manipulation+1
No attempts yet
Time limit
3s
Memory limit
2048 MB
Judgeable
Shark Growing
Medium4
Greedy, Sorting
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Yukhoe Bibimbap
Medium4
Dynamic programming, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cupid of Love
Medium4
Graph, DFS
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
ESC
Medium4
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
String Construction
Medium4
Math, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Weighted Lottery
Medium4
Math, Probability+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Heiroglyphics
Medium4
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Corrupted Gradebook
Medium4
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Unique Dice
Medium4
Hash map, Implementation
No attempts yet
Time limit
7s
Memory limit
1024 MB
Judgeable
Dao's Race Competition
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Uncle Fyodor's Candies
Medium4
Math, Binary search
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Rooks
Medium4
Sorting, Hash map+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gas and Minerals
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Autobiography
Medium4
Graph, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Expedition
Medium4
Sorting, Binary search+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Numbers
Medium4
Implementation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sequence and Easy Queries
Medium4
Array, Prefix sum
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Another Sequence Problem
Medium4
Number theory, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mobis Study
Medium4
Graph, Shortest path
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Postman
Medium4
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Company
Medium4
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Contest Advancement
Medium4
Greedy, Hash map
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Horns and Hooves
Medium4
Sorting, Prefix sum
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Nano alarm-clocks
Medium4
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Superfactorial Numeral System
Medium4
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Microcircuits
Medium4
Combinatorics, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
KSA String
Medium4
String, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Yanggallae Rescue
Medium4
Tree, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fractal Sequence
Medium4
Math, Combinatorics
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
DP (Small)
Medium4
Dynamic programming, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Candy Factory
Medium4
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Training
Medium4
Greedy, Simulation
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Jaewoo's Retake 1
Medium4
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sequence Rotation and Queries
Medium4
Array, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Play Onwards
Medium4
Graph, String matching+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shopping 2
Medium4
Array, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Seats 2
Medium4
Sorting, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Many Digits
Medium4
Sorting, Binary search+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Special Oreum Climb
Medium4
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Special Cake
Medium4
Array, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Books
Medium4
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
KMOP
Medium4
Dynamic programming, String
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Walking Along a Fence
Medium4
Prefix sum, Array+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sequence and Queries
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fix the Expression
Medium4
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Making a Timetable with 22 Credits
Medium4
Backtracking, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Warehouse Keeper
Medium4
BFS, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sloppy Acorn Classifier
Medium4
Array, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
The Jade Mask
Medium4
Geometry, Brute force+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Password Generation
Medium4
Dynamic programming, Prefix sum
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The True FA Student
Medium4
Dynamic programming, Simulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Ternary OR and Queries
Medium4
Trie, Greedy
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
DartsGiven an N by N grid of scores and an accuracy L, find the cell whose clipped (2L+1) by (2L+1) neighborhood has the highest average score.	Medium4	Prefix sumMatrix	No attempts yet	1s	1024 MB	Judgeable
RallyGiven an undirected road graph, find four distinct cities forming a cycle, or report that no such track exists.	Medium4	GraphBrute force	No attempts yet	0.5s	1024 MB	Judgeable
Sieve GameGiven a target array t, find the fewest operations that add or subtract 1 on all multiples of an index i to reach t, or print -1 if impossible.	Medium4	Number theoryImplementation	No attempts yet	1s	1024 MB	Judgeable
Mysterious wordsGiven a dictionary of words, find the longest chain of dictionary words where each one is formed by deleting a single letter from the previous one, and output the chain's length.	Medium4	Dynamic programmingHash map+1	No attempts yet	1s	1024 MB	Judgeable
Oak Tree HeightsGiven N oak heights and a neighbor distance D, find the oak whose height exceeds the average height of its neighbors by the largest margin.	Medium4	Prefix sumArray	No attempts yet	1s	1024 MB	Judgeable
Stubborn Little FrogFind the least total fly-catching time for a frog to hop from leaf 0 to the shore leaf, jumping at most L leaves at a time.	Medium4	Dynamic programmingSliding window	No attempts yet	1s	1024 MB	Judgeable
Lietus (Rain)Given the heights of N columns in a box, find how many unit cubes of rainwater stay trapped between the columns.	Medium4	ArrayTwo pointers	No attempts yet	1s	1024 MB	Judgeable
SnakeGiven a screen of width N and height M filled by a spiral snake with its head at (0, 0), find the length in cells from the head to body cell (X, Y).	Medium4	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Break a PrisonFind the fewest moves from S to E on a grid where two consecutive moves may not turn right, and surveillance cells are blocked.	Medium4	BFSGraph+1	No attempts yet	2s	1024 MB	Judgeable
Ducks and the Clapping ChunbaeGiven N quack times and a window K, find the fewest claps so that every interval [X_i, X_i+K] contains at least one clap.	Medium4	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Museum TourGiven each kitten's viewing order, find the hall where the entrance minimizes the total walking distance for all kittens, choosing the smallest number on ties.	Medium4	Prefix sumGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Chunbae Who Stole Nabi's SnackChunbae picks Crouch, Walk on all fours, or Scare Nabi each turn to keep the most HP after N punches, with damage reduced by distance.	Medium4	Dynamic programmingBrute force	No attempts yet	1s	1024 MB	Judgeable
RebirthDecide whether choosing Correct or Wrong for each of K problems can move Sii from dimension M to 0 while avoiding L unstable dimensions.	Medium4	Dynamic programmingArray	No attempts yet	1s	512 MB	Judgeable
JamboreeSplit N item sizes among M scouts, each taking one or two items, and find the smallest possible largest total carried.	Medium4	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Symmetry of StarsGiven n stars, find the point p that maximizes how many stars have a partner whose midpoint with them is p, and output that count.	Medium4	Hash mapSorting+1	No attempts yet	2s	1024 MB	Judgeable
Group Jump RopeGiven student heights, find the largest group that can line up so heights strictly rise toward the middle and then strictly fall, so no one faces someone as tall or taller.	Medium4	Dynamic programmingArray	No attempts yet	1s	1024 MB	Judgeable
Hanging a BannerGiven pole positions and flagpole lengths, pick two poles and one flagpole to get the largest triangle area that does not exceed R.	Medium4	Brute forceBinary search+2	No attempts yet	1s	1024 MB	Judgeable
SwitchChoose windows of three consecutive seconds, none overlapping, to double their points, and find the maximum total score.	Medium4	Dynamic programmingArray	No attempts yet	1s	1024 MB	Judgeable
FishingFor each query (W, P), the task is to sum the fish caught by bait placed at (W, P) that is reeled diagonally up-left until it leaves the grid.	Medium4	Prefix sumMatrix	No attempts yet	2s	1024 MB	Judgeable
K-StringCount the index pairs of 10-digit strings whose concatenation contains exactly K distinct digits.	Medium4	Bit manipulationHash map+1	No attempts yet	1s	1024 MB	Judgeable
Why Hoban-woo Was Late to School 4Given N king slimes and M items, report the total slime count after each item, where merging groups of sizes s and t adds s+t-1 mini slimes.	Medium4	Union-findImplementation	No attempts yet	1s	1024 MB	Judgeable
InversionsGiven a string S and an integer N, count the inversions in S repeated N times, modulo 10^9+7.	Medium4	MathString+1	No attempts yet	0.5s	1024 MB	Judgeable
Geometry GameGiven four points in clockwise order, report whether the quadrilateral is a square, rectangle, rhombus, parallelogram, trapezium, kite, or none.	Medium4	GeometryImplementation	No attempts yet	1s	1024 MB	Judgeable
SASA ManitoGiven the revealed Manito pairs, count the students who can be Sejong's Manito, printing NOJAM when exactly one is possible.	Medium4	ImplementationGraph	No attempts yet	1s	1024 MB	Judgeable
Hate Stagnant WaterCount the h by w rectangles on an N by M grid that contain no standing water, where drained cells spread to neighbors at equal or higher height.	Medium4	BFSPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Prof. Fumblemore and the Collatz ConjectureGiven a string of E and O letters, find the smallest positive integer whose Collatz sequence type matches it, or report INVALID for a malformed string.	Medium4	Brute forceSimulation+1	No attempts yet	1s	1024 MB	Judgeable
KlyukaloFind the fewest 1-gram weight changes that bring the total weighted deviation of N parts down to at most K.	Medium4	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
First Solved, Last CodedGiven sequences a and b, find push and pop actions on a stack that turn a into b, or report NO if impossible.	Medium4	StackGreedy+1	No attempts yet	2s	1024 MB	Judgeable
AlloysGiven n points with flexibility and conductivity, list the IDs of points that no other point beats on both values, sorted as strings.	Medium4	SortingArray	No attempts yet	15s	1024 MB	Judgeable
Heavy RainfallGiven mountain heights, sum the sizes of the lakes that can form between higher peaks, excluding any lake that touches ground (height 0).	Medium4	ArrayTwo pointers+1	No attempts yet	10s	1024 MB	Judgeable
Variable AssignmentsGiven M equations of the form x_i = x_j or x_i = -x_j, mark each as new, existing, or contradicting, stopping at the first contradiction.	Medium4	Union-find	No attempts yet	4s	1024 MB	Judgeable
ConstructiveFind a permutation of 1 to N that maximizes the total of all contiguous subarray sums.	Medium4	GreedySorting+1	No attempts yet	1s	1024 MB	Judgeable
Dance TimeCount the dance choices Hoyeong can make over N rounds so that he errs at most once, where the correct move depends on Woojin's facing direction.	Medium4	Dynamic programmingImplementation	No attempts yet	1s	1024 MB	Judgeable
March FirstMove water between three sukwoo, where each move cools the water by 5 degrees, to reach the target temperatures and final arrangement in at most 40 moves.	Medium4	BFSSimulation	No attempts yet	1s	1024 MB	Judgeable
Sorting the StripGiven N distinct numbers on a strip, find the fewest cuts so that pieces, each reversible, can be rearranged into ascending order.	Medium4	ArraySorting	No attempts yet	1s	1024 MB	Judgeable
Count of Maximum-Sum Same-Value PairsGiven an array, find the largest sum of a subarray whose two endpoints hold equal values, and count how many such subarrays reach that sum.	Medium4	Hash mapPrefix sum	No attempts yet	1s	1024 MB	Judgeable
LabirintGiven a grid of rooms joined by doors in four colors, find the fewest door colors needed to connect two rooms for each query.	Medium4	Bit manipulationUnion-find+1	No attempts yet	1s	1024 MB	Judgeable
Sum of Consecutive PrimesGiven n up to 1,000,000, decide whether n is the sum of q consecutive primes for some prime q, across multiple test cases.	Medium4	Prefix sumMath+1	No attempts yet	0.7s	1024 MB	Judgeable
Trapping the StarCounts the first-column cells where a star that moves by each cell's value and turns clockwise never leaves the grid, and lists their rows.	Medium4	SimulationImplementation	No attempts yet	1s	512 MB	Judgeable
Maze RepairEach cell points to a neighbor or outside the grid. Find the minimum cost of jump pads so that every starting cell escapes, which means hitting every cycle.	Medium4	GraphImplementation	No attempts yet	2s	1024 MB	Judgeable
Unusual competitionsGiven a bracket string of length up to 10^6, find the minimum total length of subsegment reorders needed to make it correct, or -1 if impossible.	Medium4	StringPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Watching TV SeriesGiven ad start times on two channels, find the total time Alyona spends on each channel when she switches at every ad on the channel she is watching.	Medium4	SimulationBinary search	No attempts yet	2s	1024 MB	Judgeable
Sowing WorkGiven a w by h garden, find the maximum total area covered by one or two non-overlapping axis-aligned integer squares.	Medium4	MathGreedy	No attempts yet	2s	1024 MB	Judgeable
Maximum Sum with Equal EndpointsGiven an array, find the contiguous subarray with equal first and last elements that has the maximum sum, and report the sum and its endpoints.	Medium4	Hash mapPrefix sum+1	No attempts yet	3s	1024 MB	Judgeable
Gahee and TravelConnect city 1 to all other cities using purchasable railway lines at minimum total cost, and report the latest build time among the chosen lines.	Medium4	Minimum spanning treeSorting+1	No attempts yet	1.5s	512 MB	Judgeable
Fruit TanghuluGiven a sequence of N fruit types (1 to 9), find the longest contiguous subarray that contains at most two distinct values.	Medium4	Sliding windowHash map	No attempts yet	2s	1024 MB	Judgeable
Gunggong Punch Arithmetic SequenceGiven a sequence A, find the fewest +1 increments that turn it into an arithmetic sequence with common difference K.	Medium4	ArrayGreedy+1	No attempts yet	1s	1024 MB	Judgeable
Magic CardsGiven K cards that each list numbers from 1 to N, and each friend's yes/no answers, find the number each friend picked, or 0 if it is not unique.	Medium4	Hash mapBit manipulation+1	No attempts yet	3s	2048 MB	Judgeable
Shark GrowingShak starts at size T and may eat at most K sharks strictly smaller than its current size, growing by each one. Find the largest reachable size.	Medium4	GreedySorting	No attempts yet	1.5s	1024 MB	Judgeable
Yukhoe BibimbapBosun must visit all N stations in some order where consecutive glare products stay at most K, maximizing the sum of A of the previous station times B of the next.	Medium4	Dynamic programmingBit manipulation	No attempts yet	1s	512 MB	Judgeable
Cupid of LoveGiven heights and height thresholds for female and male students, find the maximum number of pairs where each partner prefers the other.	Medium4	GraphDFS	No attempts yet	1s	512 MB	Judgeable
ESCGiven n, output a_n + b_n + c_n for the n-th derivative of e^x sin x cos x, written in the basis e^x sin^2 x, e^x cos^2 x, e^x sin x cos x.	Medium4	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
String ConstructionCount the pairs of length-N uppercase strings whose longest common subsequence made only of 'A' has length exactly M, modulo 998244353.	Medium4	MathCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
Weighted LotteryGiven the other players' picks and K draws, choose 3 distinct numbers that maximize Haru's probability of winning the lottery.	Medium4	MathProbability+1	No attempts yet	1s	1024 MB	Judgeable
HeiroglyphicsCounts the distinct words that fit a tablet pattern with '?' gaps, where no two vowels are adjacent and at least one vowel appears.	Medium4	Dynamic programmingCombinatorics+1	No attempts yet	1s	1024 MB	Judgeable
Corrupted GradebookSplit each digit string into exactly G grades from 0 to 100 with no leading zeros, then print the largest possible average rounded to the nearest integer.	Medium4	Dynamic programmingString	No attempts yet	1s	1024 MB	Judgeable
Unique DiceGiven n dice with six face values each, find the largest group of dice that match after some rotation.	Medium4	Hash mapImplementation	No attempts yet	7s	1024 MB	Judgeable
Dao's Race CompetitionFind the fewest tracks to extend by K (each at most once) so the lengths strictly increase, or report -1 if impossible.	Medium4	Dynamic programmingArray	No attempts yet	1s	1024 MB	Judgeable
Uncle Fyodor's CandiesGiven n candies, decide whether they can form a truncated tetrahedral pyramid of consecutive triangular layers, where each layer's side is one less than the layer above.	Medium4	MathBinary search	No attempts yet	2s	1024 MB	Judgeable
RooksGiven two players' rooks on a plane, find each rook that has an opposing rook as its nearest neighbor in the same row or column.	Medium4	SortingHash map+1	No attempts yet	2s	1024 MB	Judgeable
Gas and MineralsGiven minerals and gas budgets and n building types with costs and defense values, unbounded knapsack with two resource constraints finds the maximum total defense.	Medium4	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
AutobiographyCount the ordered paths u-v-w-x of four distinct vertices in an undirected graph whose colors alternate b, o, b, o.	Medium4	GraphImplementation	No attempts yet	1s	1024 MB	Judgeable
ExpeditionFor each target point on a road, find the minimum fuel to land on one pad and then walk to the target, where walking costs C per unit of length.	Medium4	SortingBinary search+1	No attempts yet	1s	1024 MB	Judgeable
NumbersGiven x and a flag k, find the smallest y at least x whose digits are all equal, or all equal except one digit when k is 1.	Medium4	ImplementationBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Sequence and Easy QueriesWith point updates on an array, count the maximal runs of equal adjacent values inside each queried subarray.	Medium4	ArrayPrefix sum	No attempts yet	2s	1024 MB	Judgeable
Another Sequence ProblemPrint N distinct integers from 1 to 10^9 so that for every pair, the sum of the two does not divide their product.	Medium4	Number theoryMath	No attempts yet	1s	1024 MB	Judgeable
Mobis StudyFind every city that lies on at least one shortest road path from city A to city B, and print them in ascending order.	Medium4	GraphShortest path	No attempts yet	2s	1024 MB	Judgeable
PostmanPencho starts at house K and always walks to the nearest unvisited house, with ties going to the lower number. Find the total distance he walks.	Medium4	GreedySimulation	No attempts yet	1s	1024 MB	Judgeable
CompanyGiven a company tree, print the lexicographically smallest seating order where each manager sits left of their subordinates and every team occupies a contiguous block.	Medium4	TreeDFS+1	No attempts yet	1s	1024 MB	Judgeable
Contest AdvancementGiven teams in rank order with their school IDs and a per-school cap c, pick the k teams to advance, filling leftover slots with the highest-ranked remaining teams.	Medium4	GreedyHash map	No attempts yet	2s	2048 MB	Judgeable
Horns and HoovesGiven horn types and hoof types, each with a cost and a count, count the pairs where the horn costs more, costs the same, or costs less than the hoof.	Medium4	SortingPrefix sum	No attempts yet	2s	1024 MB	Judgeable
Nano alarm-clocksGiven n clocks on a 12-hour dial, find the target time that minimizes the total forward shift needed to reach it, and print that total as h m s.	Medium4	SortingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Superfactorial Numeral SystemConvert the fraction p/q into superfactorial digits a_1, a_2, ... where each a_k is below k and is weighted by 1/k!.	Medium4	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
MicrocircuitsCount the ways to draw exactly k non-crossing lines between n contacts placed on a circle, where each line joins two contacts.	Medium4	CombinatoricsMath	No attempts yet	2s	1024 MB	Judgeable
KSA StringGiven a string X, find the fewest deletions and front or end insertions that turn it into the KSA-periodic string of the same length.	Medium4	StringGreedy	No attempts yet	1s	1024 MB	Judgeable
Yanggallae RescueGiven a tree rooted at room 1, find the minimum total thickness of vines to cut so that no leaf room stays connected to room 1.	Medium4	TreeDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
Fractal SequenceCount the sequences A of N distinct positive integers whose sorted version B satisfies the fixed-point condition, printed modulo M.	Medium4	MathCombinatorics	No attempts yet	1s	1024 MB	Judgeable
DP (Small)For each queried problem, find the longest sequence ending at it where both the problem numbers and the difficulties strictly increase.	Medium4	Dynamic programmingArray	No attempts yet	2s	1024 MB	Judgeable
Candy FactoryGiven each factory's candy count, find the fewest extra candies needed so all candies can be packed into full packs of k distinct types with none left over.	Medium4	MathGreedy	No attempts yet	1s	2048 MB	Judgeable
TrainingGiven problems with skill ranges [l, r] in a fixed order, choose which to solve so the final skill level is maximized, where a solve needs the current skill inside the range.	Medium4	GreedySimulation	No attempts yet	1s	2048 MB	Judgeable
Jaewoo's Retake 1Find the minimum time to swim from (0,0) to (w,d) in a pool where each lane has its own cost per unit distance, moving only parallel to the axes.	Medium4	Dynamic programmingGreedy	No attempts yet	1s	1024 MB	Judgeable
Sequence Rotation and QueriesGiven an array with right and left rotation queries, answer range sum queries over positions a to b after each rotation.	Medium4	ArrayPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Play OnwardsSplit N words into two non-empty lists so that no two words in the same list share a length-K substring, or report that no split exists.	Medium4	GraphString matching+1	No attempts yet	1s	512 MB	Judgeable
Shopping 2Given item prices and types, each query asks the total paid for items L to R on day T, when only items of type T are half price that day.	Medium4	ArraySorting+1	No attempts yet	2s	1024 MB	Judgeable
Seats 2For each player, find the smallest seat distance to a player from a different country when N players sit on a line.	Medium4	SortingArray	No attempts yet	2s	1024 MB	Judgeable
Many DigitsGiven arrays A and B, count the total number of decimal digits across all N^2 sums A_i + B_j for every pair (i, j).	Medium4	SortingBinary search+1	No attempts yet	2s	1024 MB	Judgeable
Special Oreum ClimbFind the highest y coordinate on any valid path from (0, 0) to (2N, 0) that avoids teacher points, or report -1 if no such path exists.	Medium4	Dynamic programmingImplementation	No attempts yet	1s	1024 MB	Judgeable
Special CakeGiven N statements about a cake thief, find every student who could be the culprit if all others tell the truth and the culprit lies on every statement.	Medium4	ArrayImplementation	No attempts yet	1s	1024 MB	Judgeable
BooksPick which books to read in full (a minutes each) and which by cover only (b minutes each) within t minutes to maximize the total attraction of fully read books.	Medium4	GreedyPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
KMOPPick a prefix of 1 to 3 letters from each word so the concatenated acronym has no three consonants in a row, minimizing its length.	Medium4	Dynamic programmingString	No attempts yet	0.5s	1024 MB	Judgeable
Walking Along a FenceGiven a rectilinear fence loop and each cow's start and end points on it, find the shorter walking distance along the fence for each cow.	Medium4	Prefix sumArray+1	No attempts yet	2s	1024 MB	Judgeable
Sequence and QueriesCount triples (i, j, k) where the length-k runs starting at positions i and j satisfy s[i+t] <= s[j+t] for every offset t below k.	Medium4	Dynamic programmingArray	No attempts yet	1s	1024 MB	Judgeable
Fix the ExpressionGiven a T/F expression with \| and & evaluated left to right, find the fewest value or operator changes needed to reach the desired result C.	Medium4	Dynamic programming	No attempts yet	2s	1024 MB	Judgeable
Making a Timetable with 22 CreditsCount the ways to pick at most one course per group so that no two chosen courses overlap in time and the credits total exactly 22.	Medium4	BacktrackingBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Warehouse KeeperGiven a row of 10 cells with a robot, a box, and a target, find the fewest robot commands needed to push the box onto the target, or -1 if impossible.	Medium4	BFSImplementation	No attempts yet	1s	1024 MB	Judgeable
Sloppy Acorn ClassifierFor each acorn, find the first hole it falls out of, given that the acorn shrinks by 1 after each hole it passes.	Medium4	ArrayBinary search	No attempts yet	1s	1024 MB	Judgeable
The Jade MaskGiven N points with no three collinear, count the four-point subsets that form a convex quadrilateral.	Medium4	GeometryBrute force+1	No attempts yet	1s	1024 MB	Judgeable
Password GenerationCount the length-M strings over letters A to Z where each pair of adjacent letters is at least N apart, modulo 1,000,000,007.	Medium4	Dynamic programmingPrefix sum	No attempts yet	1s	512 MB	Judgeable
The True FA StudentFind the minimum time to reach zone N, choosing at each crosswalk whether to wait for the green signal or take the footbridge.	Medium4	Dynamic programmingSimulation	No attempts yet	1s	512 MB	Judgeable
Ternary OR and QueriesMaintain a set S of integers and, for each query x, print the largest OR_3(a, x) over all a in S, where OR_3 takes digit-wise maxima in base 3.	Medium4	TrieGreedy	No attempts yet	4s	1024 MB	Judgeable