Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,613 problems

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
Snail
Medium6
Math, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Difficult Problems
Medium6
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
The Last Battle
Medium6
Array, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cute Common Divisor
Medium6
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Robot
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
GCD and LCM
Medium6
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sequence Transformation
Medium6
Array, Sliding window+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bank
Medium6
Simulation, Heap+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two Prefixes
Medium6
String, String matching+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Currency Exchange
Medium6
Array, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Expedition
Medium6
Graph, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pizza Oven
Medium6
Greedy, Math+2
No attempts yet
Time limit
0.25s
Memory limit
256 MB
Judgeable
Substring
Medium6
String matching, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Station <<Sorting>>
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sudoku (Hard)
Medium6
Backtracking, Implementation+2
No attempts yet
Time limit
0.1s
Memory limit
512 MB
Judgeable
I Hate Change
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Delivering Rice Cakes
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Let's Kill the Monster!
Medium6
Brute force, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Wicked Lord Hyeyu
Medium6
Minimum spanning tree, Graph+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Advertising Billboard
Medium6
Union-find, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Square, Not Rectangle
Medium6
Stack, Array+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Road Reconstruction
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Robot on a Conveyor Belt
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Wizard Shark and Firestorm
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Paint By Numbers
Medium6
Dynamic programming, String+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hobanwoo and the Rhythm Game
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Parity Constraint Shortest Path
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fired Runner on the Construction Site
Medium6
Shortest path, BFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Wiggly Hoseok Caterpillar - Efficiency
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Alley Boss Hoseok - Efficiency 2
Medium6
Binary search, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Paper Folding
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Why Puang Crossed the Road
Medium6
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Calendar
Medium6
Implementation, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Jinwoo's Mint Chocolate Milk
Medium6
Backtracking, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Straight Switch Game
Medium6
BFS, Graph+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Binary Seating
Medium6
Probability, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
SBC Hangar
Medium6
Combinatorics, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ká entre Nós
Medium6
Graph, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lavaspar
Medium6
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sogang Muscle Man
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Halloween Bully
Medium6
Graph, Union-find+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Password Creation
Medium6
Bit manipulation, Binary search+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Great Flood
Medium6
Union-find, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fenomenalni Fenjer
Medium6
Geometry, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
MVP Diamond (Easy)
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
MVP Diamond (Normal)
Medium6
Dynamic programming, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
String Game 2
Medium6
String, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
🎵I hate you, hate you, hate you so much, hate you, don't come near me, stop bothering me🎵 - 1
Medium6
Sorting, Intervals+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Big Linear Collider
Medium6
Stack, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Royal Dynasty
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Birthday
Medium6
Intervals, Heap+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cosmic Settlement
Medium6
Binary search, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Hyper Checkers Score Counting
Medium6
Sorting, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Fortress Defense
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Communication Network Between Vertices
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1536 MB
Judgeable
Taeyoung Throws Bombs
Medium6
Prefix sum, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Recess Rocks
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Non-Trivial Common Divisor
Medium6
Number theory, Hash map+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Rooks Game
Medium6
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Spellbook
Medium6
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chrome
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Social Distancing
Medium6
BFS, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lookup Performance
Medium6
Tree, Binary search+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Colored Squares
Medium6
Two pointers, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Temple Maze
Medium6
BFS, Bit manipulation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Gaggle
Medium6
Greedy, Graph+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tram
Medium6
Math, Geometry+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Alloys
Medium6
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
TV Watching
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Group Division
Medium6
Greedy, Union-find+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Closing Ceremony
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fire Mountain
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tower Building
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Armrests
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pekgalsvalsen
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Walking Is Annoying
Medium6
Greedy, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Seongsipdang
Medium6
Bit manipulation, Greedy+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Composite Factorization
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Po
Medium6
Greedy, Stack+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Furniture
Medium6
Union-find, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Auction Market
Medium6
Greedy, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Prize Coupon
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Dominating Duos
Medium6
Stack, Array+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Early Orders
Medium6
Stack, Greedy+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Comfortable Cows
Medium6
Implementation, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Phone Hoseokman
Medium6
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Quiz
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
T-shirts
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hundraelva kronor
Medium6
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Buying Paintings
Medium6
Dynamic programming, Array
No attempts yet
Time limit
14s
Memory limit
1024 MB
Judgeable
Minigolf
Medium6
BFS, Graph+2
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Konami Code
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Average distance
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pachinko
Medium6
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ranking
Medium6
Sorting, Simulation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Fitness Club
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Racing
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Labyrinth
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
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
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
Difficult ProblemsGiven a string of lowercase letters and 'A's, split the 'A's into the maximum number of groups with distinct positive sizes, allowing lowercase letters between groups.	Medium6	GreedyMath+2	No attempts yet	1s	512 MB	Judgeable
The Last BattleA permutation a is fixed; rotating the identity arrangement right by k positions must satisfy a[i] != shifted value at each position. Find the smallest valid k, or -1.	Medium6	ArrayMath+2	No attempts yet	1s	512 MB	Judgeable
Cute Common DivisorGiven a and b up to 1e9, find a common divisor d whose digit sum is as large as possible, and print any such divisor.	Medium6	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
RobotGiven a sequence of signed step sizes, flip at most k signs to maximize the absolute value of the final position.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
GCD and LCMGiven a and b, find positive x <= y with the same gcd and lcm as a and b, minimizing y - x.	Medium6	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Sequence TransformationGiven a sequence of non-negative integers, find the minimum number of single increments needed so that 1,2,...,h appear consecutively as a block, or report that it is impossible.	Medium6	ArraySliding window+2	No attempts yet	2s	512 MB	Judgeable
BankGiven n dwarves with arrival times, employee service times, and accountant times, simulate a shared employee queue of m servers and a single accountant to find each dwarf's departure time.	Medium6	SimulationHeap+2	No attempts yet	2s	512 MB	Judgeable
Two PrefixesGiven strings s and t, count distinct strings formed by concatenating a non-empty prefix of s with a non-empty prefix of t.	Medium6	StringString matching+2	No attempts yet	1s	512 MB	Judgeable
Currency ExchangeGiven n tablet values and an integer rate p, find two distinct indices i and j so that the ratio c_i / c_j is as close to p as possible.	Medium6	ArrayBinary search+2	No attempts yet	2s	512 MB	Judgeable
ExpeditionEach candidate forbids at most one other candidate; choose the largest subset where no included candidate's forbidden partner is also included.	Medium6	GraphGreedy+2	No attempts yet	2s	512 MB	Judgeable
Pizza OvenFind the fewest button presses (ADDH, ADDT, MINT, ADDO, MINO) to reach a target time, breaking ties by lexicographically smallest press counts.	Medium6	GreedyMath+2	No attempts yet	0.25s	256 MB	Judgeable
SubstringGiven string s and n queries (l, r, t), for each one check whether t occurs as a substring of s from position l to r.	Medium6	String matchingBinary search+1	No attempts yet	2s	512 MB	Judgeable
Station <<Sorting>>Given n distinct masses in a row, you may swap two adjacent cars only when their total mass is at most M; decide whether sorting by increasing mass is reachable.	Medium6	SortingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Sudoku (Hard)Fill a 9x9 Sudoku grid so every row, column, and 3x3 box holds the digits 1 to 9 exactly once.	Medium6	BacktrackingImplementation+2	No attempts yet	0.1s	512 MB	Judgeable
I Hate ChangeGiven N fractions, find the largest fraction that divides every given fraction exactly, with the answer reduced to lowest terms.	Medium6	MathNumber theory+2	No attempts yet	1s	512 MB	Judgeable
Delivering Rice CakesGiven a weighted graph, a start house Y, and a daily walking limit X, find how many days it takes to visit every other house if each day's trip must return to Y and stay within X.	Medium6	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Let's Kill the Monster!Each skill takes 1 second to cast, then deals its damage; after casting you must wait out its cooldown. Find the earliest time the monster's HP reaches zero.	Medium6	Brute forceSimulation+2	No attempts yet	2s	512 MB	Judgeable
Wicked Lord HyeyuBuild a minimum spanning tree over N villages with K weighted edges, then report the largest shortest-path distance between any two villages in that tree.	Medium6	Minimum spanning treeGraph+2	No attempts yet	0.5s	512 MB	Judgeable
Advertising BillboardGiven k on/off patterns for an n by m grid of bulbs, partition the bulbs into the fewest groups so that within each pattern every group is uniformly on or uniformly off.	Medium6	Union-findImplementation+2	No attempts yet	2s	512 MB	Judgeable
Square, Not RectangleGiven bar heights of a histogram with unit widths, find the side length of the largest axis-aligned square that fits inside it.	Medium6	StackArray+2	No attempts yet	1.5s	1024 MB	Judgeable
Road ReconstructionGiven a grid where cells cost 0, 1, or 2 to cross and -1 is blocked, find the minimum total construction cost of a path from the top-left to the bottom-right cell.	Medium6	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Robot on a Conveyor BeltSimulate a rotating conveyor belt where robots load, advance when possible, and stop once K cells have zero durability, reporting the step count.	Medium6	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Wizard Shark and FirestormRepeat Q times: rotate every 2^L x 2^L block 90 degrees clockwise, then subtract 1 from each ice cell that has fewer than 3 ice neighbors. Output the total ice and the largest connected ice chunk.	Medium6	ImplementationSimulation+2	No attempts yet	1s	512 MB	Judgeable
Paint By NumbersGiven a row of n cells, clue block lengths, and some fixed cells, find which cells are black or white in every valid painting.	Medium6	Dynamic programmingString+1	No attempts yet	2s	512 MB	Judgeable
Hobanwoo and the Rhythm GameGiven note scores, choose which notes to miss so that no three consecutive notes are missed, maximizing the sum of combo times score over the notes that are hit.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	256 MB	Judgeable
Parity Constraint Shortest PathGiven an undirected weighted graph, find for every vertex the minimum cost of an even path and of an odd path from vertex 1, allowing repeated vertices and edges.	Medium6	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
Fired Runner on the Construction SiteFind the earliest time to reach the bottom-right cell, where each cell must be entered before its deadline and straight runs speed up.	Medium6	Shortest pathBFS+1	No attempts yet	1s	1024 MB	Judgeable
Wiggly Hoseok Caterpillar - EfficiencyChoose disjoint consecutive blocks of food, each summing to at least K, to maximize the total sum minus K times the number of blocks.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Alley Boss Hoseok - Efficiency 2Find the minimum possible maximum edge toll along a path from A to B whose total toll is at most C, or -1 if no path fits the budget.	Medium6	Binary searchGraph+2	No attempts yet	5s	512 MB	Judgeable
Paper FoldingGiven k, a sequence of 2k folds, and one punched corner of the final unit square, print the full grid of hole positions after unfolding.	Medium6	ImplementationSimulation+2	No attempts yet	0.5s	512 MB	Judgeable
Why Puang Crossed the RoadGiven a line Ax+By+C=0 and an axis-aligned rectangle, decide whether the line passes through the rectangle's interior; touching only a corner or edge does not count.	Medium6	GeometryMath+1	No attempts yet	1s	512 MB	Judgeable
CalendarPlace each schedule as high as possible on a 365-day calendar, group horizontally consecutive days into rectangles, and print the total coated area.	Medium6	ImplementationSorting+2	No attempts yet	1s	512 MB	Judgeable
Jinwoo's Mint Chocolate MilkOn an N x N grid with one home, at most ten milk spots, initial stamina M, and stamina gain H per drink, find the most bottles Jinwoo can drink and still return home.	Medium6	BacktrackingBFS+2	No attempts yet	1s	512 MB	Judgeable
Straight Switch GameEach switch adds its own index (mod 5) to the cubes it connects; find the fewest presses that make every cube's value equal, or report -1.	Medium6	BFSGraph+2	No attempts yet	1.5s	512 MB	Judgeable
Binary SeatingEach of n students independently picks room 0 or room 1 with equal probability; compute the expected maximum finish time among the students who pick room 1.	Medium6	ProbabilityDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
SBC HangarCount the K-element subsets of N distinct weights whose sum lies in [A, B], given that each weight is at least twice the next smaller one.	Medium6	CombinatoricsSorting+2	No attempts yet	2s	512 MB	Judgeable
Ká entre NósGiven an undirected graph with P vertices and F edges, decide whether the vertices can be split into at most two groups so that every vertex has an odd number of neighbors inside its own group.	Medium6	GraphMath+2	No attempts yet	2s	512 MB	Judgeable
LavasparCount grid cells that belong to at least one contiguous straight segment (row, column, or diagonal) whose letters form an anagram of some word in the given list.	Medium6	ImplementationBrute force+2	No attempts yet	2s	512 MB	Judgeable
Sogang Muscle ManPair up N machines into floor(N/2) pairs plus possibly one leftover so the largest pair sum is minimized, and report that smallest possible maximum.	Medium6	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Halloween BullyGiven a graph of friendships with candy amounts, pick groups (connected components) whose total size stays under K, maximizing total candy.	Medium6	GraphUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Password CreationGiven N and a set of M used passwords, choose a password from 0 to N maximizing the minimum Hamming distance to any used password.	Medium6	Bit manipulationBinary search+2	No attempts yet	1s	1024 MB	Judgeable
Great FloodGiven region heights and travel times, find for each region the highest region its residents can reach while the rising water stays below their path.	Medium6	Union-findSorting+1	No attempts yet	1s	1024 MB	Judgeable
Fenomenalni FenjerPlace a point on the x-axis so that a circle of radius r centered there covers as many of the n given points as possible, and print that maximum count.	Medium6	GeometrySorting+2	No attempts yet	1s	512 MB	Judgeable
MVP Diamond (Easy)Given each month's MVP grade, which depends on the sum paid over the current and previous month, find the maximum total amount paid over all N months.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
MVP Diamond (Normal)Given the monthly MVP tiers over N months and the tier thresholds, find the maximum total spending that produces exactly those tiers.	Medium6	Dynamic programmingBrute force+2	No attempts yet	1s	512 MB	Judgeable
String Game 2For each test case, find the shortest substring containing exactly K of some character, and the longest substring that both starts and ends with that character and contains exactly K of it.	Medium6	StringSliding window+2	No attempts yet	1s	1024 MB	Judgeable
🎵I hate you, hate you, hate you so much, hate you, don't come near me, stop bothering me🎵 - 1Given N half-open intervals [entry, exit), find the maximum number of simultaneously present mosquitoes and the earliest maximal interval achieving it.	Medium6	SortingIntervals+2	No attempts yet	1s	1024 MB	Judgeable
Big Linear ColliderParticles on a line move in fixed directions and annihilate when opposite charges meet; for each query time, count how many particles remain right after that moment.	Medium6	StackSorting+2	No attempts yet	1s	512 MB	Judgeable
Royal DynastyGiven a rooted tree and queries (v, k), count the descendants of node v exactly k generations below it.	Medium6	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
BirthdayPick the friends to invite so that each invited friend's share S/(k+1) lies within their [a_i, b_i] range and the total fun is maximized.	Medium6	IntervalsHeap+1	No attempts yet	2s	512 MB	Judgeable
Cosmic SettlementGiven n rectangles of size a by b and a w by h field, find the largest integer d such that n rectangles of size (a+2d) by (b+2d) fit in a grid on the field, in either orientation.	Medium6	Binary searchMath+1	No attempts yet	1s	512 MB	Judgeable
Hyper Checkers Score CountingCount distinct ordered triples (a,b,c) drawn from n given cards such that max(a,b,c) <= k * min(a,b,c).	Medium6	SortingTwo pointers+2	No attempts yet	1s	512 MB	Judgeable
Fortress DefenseDistribute exactly s defenders among wall sections, where each defender in section i repels k_i attackers, to minimize the total attackers that break through.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Communication Network Between VerticesGiven a rooted tree and a frequency per node, count ancestor-descendant pairs whose frequencies divide one another. Since every parent index is smaller than the child, nodes are already topologically ordered.	Medium6	MathNumber theory+2	No attempts yet	1s	1536 MB	Judgeable
Taeyoung Throws BombsGiven the altitude grid after all first explosions, recover how many bombs landed at each cell, where each bomb lowers an MxM square by 1.	Medium6	Prefix sumImplementation+2	No attempts yet	2s	512 MB	Judgeable
Recess RocksReorder the children so that the number who see someone ahead of them with at least as many rocks is minimized.	Medium6	GreedySorting+2	No attempts yet	3s	1024 MB	Judgeable
Non-Trivial Common DivisorPick a subset of the given numbers that all share a common divisor greater than 1, maximizing the subset's sum.	Medium6	Number theoryHash map+2	No attempts yet	3s	512 MB	Judgeable
Rooks GameGiven M rooks on an N x N board, a rook captures another when they share a row or column with nothing between them; find the minimum and maximum number of captures before no captures remain.	Medium6	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
The SpellbookGiven spell costs, up to k cookies that each lower one cost by 1, and starting MP m, find the minimum rest time to cast every spell once.	Medium6	GreedySorting	No attempts yet	2s	512 MB	Judgeable
ChromeGiven N tabs each with CPU and memory usage plus a priority, choose a subset whose total CPU and memory reach the targets M and K while minimizing the sum of priorities.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	512 MB	Judgeable
Social DistancingGiven a grid with patients, blocked seats, a start, and an end, find a walk from start to end that maximizes the minimum Chebyshev distance to any patient, or report safe or -1.	Medium6	BFSBinary search+2	No attempts yet	2s	512 MB	Judgeable
Lookup PerformanceGiven a binary search tree and range queries [L, R], count how many times the recursive lookup function is called for each query.	Medium6	TreeBinary search+1	No attempts yet	2s	512 MB	Judgeable
Colored SquaresDelete at most k squares from a colored row so that the longest run of one color is as large as possible, and output that maximum run length.	Medium6	Two pointersSliding window+2	No attempts yet	1s	512 MB	Judgeable
Temple MazeA square grid has walls, a start, a goal, up to 10 rune letters, and matching levers and gates; stepping on a lever opens every gate of that letter. Find the minimum number of moves to reach the goal, or IMPOSSIBLE.	Medium6	BFSBit manipulation+2	No attempts yet	3s	512 MB	Judgeable
GaggleGiven current mentor pointers, find the lexicographically best permutation with no fixed points that forms a single cycle through all Gagglers.	Medium6	GreedyGraph+1	No attempts yet	2s	512 MB	Judgeable
TramChoose the intercept a of the line y = x + a minimizing the sum of squared distances from given points to the line.	Medium6	MathGeometry+2	No attempts yet	1s	1024 MB	Judgeable
AlloysGiven a budget c per kilogram, choose titanium, aluminium, and magnesium ratios summing to 1 with x+y at most c to maximize hardness xy.	Medium6	MathGreedy+2	No attempts yet	1s	1024 MB	Judgeable
TV WatchingGiven parties on fixed days, each discussing certain TV series, decide whether Bob can watch every required series in time, at most 10 hours per day and no watching on party days.	Medium6	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Group DivisionAssign each chair to group 1 or 2 so that every prefix is balanced within 1 and paired chairs match, choosing the lexicographically smallest sequence.	Medium6	GreedyUnion-find+2	No attempts yet	1s	1024 MB	Judgeable
Closing CeremonyGiven a row of up to 30 seats labeled A to D, find the maximum number of adjacent equal-group pairs after each person swaps at most once with someone within K seats.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	1024 MB	Judgeable
Fire MountainIn a grid where some cells are flames, find the shortest path from the top-left to the bottom-right cell while stepping on at most K flames.	Medium6	BFSGraph+2	No attempts yet	1s	1024 MB	Judgeable
Tower BuildingGiven N blocks each with a square width and height, stack a subset so width strictly decreases upward while height weakly increases upward, maximizing the total tower height.	Medium6	Dynamic programmingSorting+2	No attempts yet	3s	1024 MB	Judgeable
ArmrestsPeople sit in a ring; each person wants a specific combination of left and right armrests, and we maximize how many preferences can be satisfied since each armrest holds at most one arm.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	1024 MB	Judgeable
PekgalsvalsenGiven a string with K distinct letters, choose the order to write the letters so that the total right-arrow distance is minimized, and print that minimum.	Medium6	GreedySorting+2	No attempts yet	2s	1024 MB	Judgeable
Walking Is AnnoyingGiven N rickshaws at sorted positions, each covering a range to its right, find the minimum number of transfers to reach point M without walking.	Medium6	GreedyBFS+2	No attempts yet	1s	1024 MB	Judgeable
SeongsipdangList all 2^N binary strings of length N, starting from a given string, so that the total number of matching positions between consecutive strings is minimized.	Medium6	Bit manipulationGreedy+2	No attempts yet	3s	1024 MB	Judgeable
Composite FactorizationFactor N into a product of composite numbers, choosing the lexicographically smallest such sequence, or report that none exists.	Medium6	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
PoGiven a nonnegative array built by adding positive values to nested or disjoint segments starting from zeros, find the minimum number of such segment additions needed.	Medium6	GreedyStack+2	No attempts yet	1s	512 MB	Judgeable
FurnitureGiven a grid with furniture, decide for each query cell whether placing furniture there keeps a south-and-east path from the top-left to the bottom-right corner.	Medium6	Union-findMatrix+1	No attempts yet	1s	512 MB	Judgeable
Auction MarketBuyers in fixed order scan items left to right and bid on the first item they can afford or outbid, and we count how many items end up with a bidder.	Medium6	GreedyBinary search+2	No attempts yet	1s	512 MB	Judgeable
Prize CouponEach student has 0 to 3 coupons and may write only their own or an adjacent student's ID; maximize the number of distinct students named on at least one coupon.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Dominating DuosCount pairs (i, j) in a permutation where both endpoints exceed every element strictly between them, with n up to 10^6.	Medium6	StackArray+1	No attempts yet	4s	512 MB	Judgeable
Early OrdersGiven a sequence where every value from 1 to k appears at least once, find the lexicographically smallest subsequence that contains each of those k values exactly once.	Medium6	StackGreedy+2	No attempts yet	4s	1024 MB	Judgeable
Comfortable CowsCows arrive one at a time on a grid; after each arrival, report how many cows have exactly three occupied orthogonal neighbors.	Medium6	ImplementationHash map+2	No attempts yet	1s	512 MB	Judgeable
Phone HoseokmanGiven the same number written in two unknown bases A and B, find the base-10 value X and the two bases, reporting Multiple or Impossible.	Medium6	MathBrute force+2	No attempts yet	1s	512 MB	Judgeable
QuizPick at most K questions out of N, where finishing every question in a category adds a bonus B, and maximize the total score.	Medium6	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
T-shirtsEach of N contestants accepts t-shirt sizes in an interval [L[i], H[i]], and N t-shirt sizes are given; match as many contestants to shirts as possible.	Medium6	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Hundraelva kronorGiven N, find the fewest notes with values 1, 11, 111, ... that sum exactly to N.	Medium6	Dynamic programmingMath+2	No attempts yet	1s	1024 MB	Judgeable
Buying PaintingsThe paintings sit in a line; walking between adjacent ones costs 1 second and buying painting i costs t_i. Choose k paintings to buy, starting and ending anywhere, so the total buying plus walking time is smallest.	Medium6	Dynamic programmingArray	No attempts yet	14s	1024 MB	Judgeable
MinigolfOn a grid with walls, a ball can be putted 1 to K cells in a straight line; find the fewest putts to reach the hole.	Medium6	BFSGraph+2	No attempts yet	4s	1024 MB	Judgeable
Konami CodeGiven a string over the buttons U, N, V, H, B, A, find the minimum number of extra presses inserted between the Konami code's characters, where presses before and after the code are free.	Medium6	Dynamic programmingString+2	No attempts yet	3s	1024 MB	Judgeable
Average distanceGiven a weighted tree, compute the average distance over all unordered pairs of vertices, within 1e-6 relative or absolute error.	Medium6	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
PachinkoGiven a grid with obstacles and numbered gates, drop a ball in one column to maximize expected winnings as it falls and splits 50/50 at each obstacle.	Medium6	Dynamic programmingProbability+2	No attempts yet	1s	1024 MB	Judgeable
RankingGiven contest runs, compute each team's solved count, total penalty time, and tie-break by the last moment their score differed, then output the ranking.	Medium6	SortingSimulation+2	No attempts yet	1s	1024 MB	Judgeable
Fitness ClubAssign k lockers to n groups of visitors so that the number of lockers still locked at day's end is maximized, given each group's counts of visitors who lock and do not lock.	Medium6	Dynamic programmingGreedy+1	No attempts yet	2s	1024 MB	Judgeable
RacingA car slides from its cell toward a chosen wall, stops half the remaining distance from the first obstacle, and we need the fewest presses to reach the target.	Medium6	BFSGraph+2	No attempts yet	2s	1024 MB	Judgeable
LabyrinthGiven a 3D grid of h levels with blocked cells, find the shortest time from the start on the top level to the goal on the bottom, where horizontal moves and floor-breaking drops each cost 5 seconds.	Medium6	BFSGraph+2	No attempts yet	2s	1024 MB	Judgeable