Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,615 problems

Insiders' Rock-Paper-Scissors
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Baaaaaaaaaduk2 (Easy)
Medium6
Brute force, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Traveling Salesman 3
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sleepy Cow Sorting
Medium6
Array, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sleepy Cow Herding (Silver)
Medium6
Sorting, Sliding window+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Painting the Barn (Silver)
Medium6
Prefix sum, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Great Revegetation (Silver)
Medium6
Union-find, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Moving a Pipe 1
Medium6
Dynamic programming, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Why the Fox Climbed Information Island
Medium6
Sorting, Binary search+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Fishing King
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cake Cutting
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Comparing Strings
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Space Probe
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Nautilus
Medium6
Implementation, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Life Game
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Team Selection
Medium6
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Almost-K Increasing Subsequence
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Oh Right, the Umbrella
Medium6
BFS, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ssi Ssi
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Galactic Railway
Medium6
Union-find, Graph+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Tough Guy
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stock
Medium6
Sliding window, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Getting-Up Syndrome
Medium6
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Walk Only the Lightbulb Path
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Line Segment Intersection 2
Medium6
Geometry, Math+2
No attempts yet
Time limit
0.25s
Memory limit
512 MB
Judgeable
Finger Snap
Medium6
BFS, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
RGB Street 2
Medium6
Dynamic programming, Implementation+2
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Count of Increasing Subsequences
Medium6
Dynamic programming, Binary search+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sorting
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
0.5s
Memory limit
256 MB
Judgeable
Parallel Universe
Medium6
Math, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Jinwoo's Moon Trip (Small)
Medium6
Dynamic programming, Matrix+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Feeding the Cats
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stealing Snacks from Juniors
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Ringo and Permutation
Medium6
Greedy, Array+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Byte Coin
Medium6
Dynamic programming, Brute force+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Canal
Medium6
Binary search, Sorting+2
No attempts yet
Time limit
1.5s
Memory limit
512 MB
Judgeable
Star Trek
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Two Machines
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Getting Confidence
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Deceptive Dice
Medium6
Dynamic programming, Probability+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Exits in Excess
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Slow Leak
Medium6
Shortest path, Graph+2
No attempts yet
Time limit
14s
Memory limit
1024 MB
Judgeable
Zipline
Medium6
Geometry, Binary search+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two-Pan Balance
Medium6
Brute force, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gathering Balls
Medium6
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Colouring a rectangle
Medium6
Dynamic programming, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Count Squares
Medium6
Array, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
JOIOJI
Medium6
Prefix sum, Hash map+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Straps
Medium6
Dynamic programming, Tree+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Keep Him Inside
Medium6
Geometry, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Automatic Accountant
Medium6
Sorting, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Integral Pyramid
Medium6
Combinatorics, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Seungbeom's Interviews
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Bus Planning
Medium6
Bit manipulation, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Typo Squatting
Medium6
Hash map, String+2
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Streaming Services
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Haiku
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gazzzua
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Subway
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Domino Prediction
Medium6
Prefix sum, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Alehouse
Medium6
Intervals, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
One of Each
Medium6
Greedy, Stack+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sculptural Project
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Gluing Pictures
Medium6
Dynamic programming, String matching+2
No attempts yet
Time limit
0.3s
Memory limit
512 MB
Judgeable
Polygon
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Assessing Genomes
Medium6
String, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Binary Number Game
Medium6
BFS, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ggeureuda Gimgganom
Medium6
Binary search, Array+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Robot Assembly
Medium6
Union-find, Implementation+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
A Water Slide at Catholic University??
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two Coins Unlimited
Medium6
BFS, Graph+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Bob in Wonderland
Medium6
Tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fast Forwarding
Medium6
BFS, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rubber Duck Lovers Club
Medium6
Greedy, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Milk Pumping
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Milk Visits
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Swapping Places
Medium6
Topological sort, Greedy+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Splitting DNA
Medium6
Dynamic programming, Intervals+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gold Rush
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Password
Medium6
DFS, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
ASLRDR
Medium6
Greedy, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Avoiding Surveillance
Medium6
Brute force, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Weapon Engineering
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Two Teams
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mineral 2
Medium6
Simulation, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Deliveries
Medium6
Tree, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Just Shuffle the Input
Medium6
String matching, String+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Gotta Catch 'Em All
Medium6
Binary search, Sliding window+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Football Hooliganism
Medium6
Dynamic programming, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cat
Medium6
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Team Assignment
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
0.7s
Memory limit
256 MB
Judgeable
Triangles (Silver)
Medium6
Math, Geometry+2
No attempts yet
Time limit
1s
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
Bubble Bucket Sort
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Heroic Heist
Medium6
Graph, Greedy+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Readability
Medium6
Sorting, Greedy+1
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
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

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Insiders' Rock-Paper-ScissorsWith a fixed gesture matchup table and each player's throw sequence, decide whether Jiwoo can win while never repeating a gesture, given match order Jiwoo, Kyunghee, Minho and ties favoring the later player.	Medium6	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Baaaaaaaaaduk2 (Easy)Place exactly two own stones on empty cells of a board to maximize the number of opponent stones that become completely surrounded and captured.	Medium6	Brute forceSimulation+2	No attempts yet	2s	512 MB	Judgeable
Traveling Salesman 3Find the minimum-length round trip that visits all N cities exactly once and returns to the start, where N is at most 16.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Sleepy Cow SortingFind the minimum number of moves to sort a permutation, where each move takes the front element and inserts it k positions later, and output the move sizes.	Medium6	ArrayGreedy+2	No attempts yet	2s	512 MB	Judgeable
Sleepy Cow Herding (Silver)Find the minimum and maximum moves to make N cows on a number line occupy consecutive integers, moving only the leftmost or rightmost cow each turn.	Medium6	SortingSliding window+1	No attempts yet	2s	512 MB	Judgeable
Painting the Barn (Silver)Given N axis-aligned rectangles with coordinates in 0..1000, find the total area covered by exactly K of them.	Medium6	Prefix sumArray+2	No attempts yet	2s	512 MB	Judgeable
The Great Revegetation (Silver)Count the binary assignments of grass types to N pastures that satisfy M same-or-different constraints on pairs, and print the count in binary.	Medium6	Union-findGraph+2	No attempts yet	2s	512 MB	Judgeable
Moving a Pipe 1Count the ways to push a two-cell pipe (horizontal, vertical, or diagonal) across an N by N grid of walls until one end reaches (N, N).	Medium6	Dynamic programmingSimulation+2	No attempts yet	1s	512 MB	Judgeable
Why the Fox Climbed Information IslandCount triples of stars (s,t,u) with s.x < t.x < u.x and s.y > t.y < u.y, output the count modulo 1e9+7.	Medium6	SortingBinary search+2	No attempts yet	1s	256 MB	Judgeable
Fishing KingA fisherman sweeps columns left to right, catching the lowest shark in each column while the rest slide and bounce vertically or horizontally, merging sharks that collide.	Medium6	SimulationImplementation+2	No attempts yet	1s	512 MB	Judgeable
Cake CuttingGiven cut positions on a roll cake and several target piece counts, find the largest possible minimum piece length for each count.	Medium6	Binary searchGreedy+2	No attempts yet	1s	512 MB	Judgeable
Comparing StringsGiven two lowercase strings, align them by repeating characters of either string, keeping order, and minimize the sum of absolute alphabet-position differences over aligned pairs.	Medium6	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Space ProbeGiven travel times between N planets and a start planet, find the shortest route that visits every planet, with no need to return to the start.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
NautilusGiven an R by C water and island grid plus M move signals with wildcards, count how many cells can be the submarine's current position if it never enters an island.	Medium6	ImplementationSimulation+2	No attempts yet	2s	512 MB	Judgeable
Life GameSimulate Conway-style life on an N x M board for T steps using a (2K+1) square neighborhood with thresholds a and b, then print the final board.	Medium6	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
Team SelectionPick five of n candidates and assign each a distinct role among A to E so the total skill summed over roles is as large as possible.	Medium6	Dynamic programmingBit manipulation+1	No attempts yet	1s	256 MB	Judgeable
Almost-K Increasing SubsequenceFind the longest subsequence of a given sequence that has at most K positions where consecutive elements decrease.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	256 MB	Judgeable
Oh Right, the UmbrellaOn a grid with walls, find the shortest walk from S that picks up every X item (at most 5) and ends at E.	Medium6	BFSBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
Ssi SsiGiven M facts that two people have a certain kinship distance, answer Q queries asking the distance between two people, or -1 if it cannot be determined.	Medium6	GraphShortest path+2	No attempts yet	2s	256 MB	Judgeable
Galactic RailwayAdd up to M edges between N galaxies one at a time; after each edge print the total planet count in the merged component.	Medium6	Union-findGraph+2	No attempts yet	5s	512 MB	Judgeable
Tough GuyCount the cells reachable from a start on a grid where you move up and down freely but left and right at most L and R times total, with walls blocked.	Medium6	GraphBFS+2	No attempts yet	1s	256 MB	Judgeable
StockFind the shortest subarray whose sum minus y times its length is at least Z and whose length times y is at most X, breaking ties by the latest start.	Medium6	Sliding windowPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Getting-Up SyndromeChoose an initial integer x in [0, m] so that applying n bitwise OR/XOR/AND gates with given parameters maximizes the final value.	Medium6	Bit manipulationGreedy+2	No attempts yet	1s	512 MB	Judgeable
Walk Only the Lightbulb PathArrange N binary strings in some order so the concatenation has the fewest adjacent 01 or 10 transitions, and print that minimum count; N is at most 10.	Medium6	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Line Segment Intersection 2Given two line segments by their integer endpoints, decide whether they intersect, counting endpoint touching as an intersection.	Medium6	GeometryMath+2	No attempts yet	0.25s	512 MB	Judgeable
Finger SnapStarting from N, use halve, third, increment, and decrement operations to reach a prime in [A, B] with the fewest operations, or report -1.	Medium6	BFSNumber theory+2	No attempts yet	2s	512 MB	Judgeable
RGB Street 2Paint N houses in a cycle with three colors so that every adjacent pair differs, minimizing total cost.	Medium6	Dynamic programmingImplementation+2	No attempts yet	0.5s	128 MB	Judgeable
Count of Increasing SubsequencesCount the strictly increasing subsequences of length K in a sequence of N distinct values, reported modulo 1e9+7.	Medium6	Dynamic programmingBinary search+2	No attempts yet	1s	512 MB	Judgeable
SortingGiven N and M, construct a permutation of 1..N for which insertion sort performs exactly M shifts, or report that it is impossible.	Medium6	GreedySorting+2	No attempts yet	0.5s	256 MB	Judgeable
Parallel UniverseYou leave Earth at one initial speed, may only decrease it afterward, and each leg's speed must be a positive integer multiple of its required value. Find the smallest starting speed that lets you finish all n legs.	Medium6	MathGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Jinwoo's Moon Trip (Small)Given an N by M grid of fuel costs with N, M at most 6, find the minimum cost path from any cell in the top row to any cell in the bottom row, where each step moves downward and no two consecutive steps use the same direction.	Medium6	Dynamic programmingMatrix+1	No attempts yet	1s	256 MB	Judgeable
Feeding the CatsStarting at (0,0), visit all N cats on a grid, moving in Manhattan steps, and return to (0,0) in the shortest time.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
Stealing Snacks from JuniorsChoose a subset of snacks whose total fullness reaches M, minimizing total satisfaction, or report that it is impossible.	Medium6	Dynamic programmingGreedy+1	No attempts yet	1s	256 MB	Judgeable
Ringo and PermutationGiven N and K, construct a permutation of 1..N whose inversion count is exactly K, or report that none exists.	Medium6	GreedyArray+2	No attempts yet	1s	256 MB	Judgeable
Byte CoinGiven n up to 15 days of Byte Coin prices and initial cash W, buy and sell whole coins each day to maximize the cash held after selling everything on day n.	Medium6	Dynamic programmingBrute force+2	No attempts yet	0.5s	512 MB	Judgeable
CanalPlace one horizontal and one vertical line so the largest distance from any given point to the nearer line is minimized, and print that distance.	Medium6	Binary searchSorting+2	No attempts yet	1.5s	512 MB	Judgeable
Star TrekFind the minimum travel time from planet 1 to planet n, where you may switch ships at intermediate planets, paying a preparation time plus pace times distance for each leg.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Two MachinesAssign each of n tasks to machine A or B, minimizing the maximum total load across the two machines.	Medium6	Dynamic programmingGreedy+2	No attempts yet	0.5s	512 MB	Judgeable
Getting ConfidenceGiven an N by N matrix of confidence values, assign each of N ornaments to a distinct position so that the product of the chosen values is maximized, and output the assignment.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	0.5s	512 MB	Judgeable
Deceptive DiceGiven an n-sided die and at most k rolls, find the maximum expected final score when you may stop rolling at any point.	Medium6	Dynamic programmingProbability+2	No attempts yet	1s	512 MB	Judgeable
Exits in ExcessGiven a directed graph, choose at most half of its edges to delete so that the remaining graph has no directed cycle.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Slow LeakGiven weighted roads and refill stations, find the shortest school-to-home route where no stretch between refills exceeds distance d, or report stuck.	Medium6	Shortest pathGraph+2	No attempts yet	14s	1024 MB	Judgeable
ZiplineFor each zipline, find the minimum and maximum cable length so the rider's lowest point stays at least r meters above the flat ground.	Medium6	GeometryBinary search+2	No attempts yet	1s	1024 MB	Judgeable
Two-Pan BalanceGiven up to 13 distinct weights, count how many integers from 1 to their sum cannot be formed when each weight goes on the bowl side, the other pan, or unused.	Medium6	Brute forceBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Gathering BallsGiven a row of red and blue balls, find the minimum number of jumps (moving only one color) to group each color together.	Medium6	GreedyString+2	No attempts yet	1s	512 MB	Judgeable
Colouring a rectangleEvery cell must be covered by one of its two diagonals, one going in each direction. Find the minimum total cost of diagonals that covers the whole grid.	Medium6	Dynamic programmingGraph	No attempts yet	2s	512 MB	Judgeable
Count SquaresGiven coordinates of h horizontal and v vertical lines, count how many axis-aligned squares have all four sides drawn by those lines.	Medium6	ArrayHash map+2	No attempts yet	2s	512 MB	Judgeable
JOIOJIGiven a string of J, O, and I, find the longest contiguous substring with equal counts of all three letters.	Medium6	Prefix sumHash map+2	No attempts yet	1s	512 MB	Judgeable
StrapsChoose a set of straps forming a rooted tree: each strap occupies one port of its parent, one strap hangs from the phone, and total happiness is maximized.	Medium6	Dynamic programmingTree+2	No attempts yet	1s	512 MB	Judgeable
Keep Him InsideGiven a convex polygon of guard points and an interior prisoner point, assign nonnegative weights summing to 1 whose weighted average equals the prisoner.	Medium6	GeometryMath+2	No attempts yet	1s	512 MB	Judgeable
Automatic AccountantEach coin slides along a track and drops into the first slot whose width is at least the coin's thickness and whose trigger mass is at most the coin's mass; sum the drop positions.	Medium6	SortingBinary search+2	No attempts yet	2s	512 MB	Judgeable
Integral PyramidGiven n and x, decide whether positive integers can fill the bottom row of Pascal-style sums so the single top cell equals x, and print a valid pyramid.	Medium6	CombinatoricsMath+2	No attempts yet	2s	512 MB	Judgeable
Seungbeom's InterviewsGiven a directed weighted graph with several marked sites, find the city whose shortest distance to any site is largest, and report that distance.	Medium6	GraphShortest path+2	No attempts yet	1s	256 MB	Judgeable
Bus PlanningSplit n kids (n up to 17) into the fewest groups so no two enemies share a group and each group has at most c kids, then output one valid grouping.	Medium6	Bit manipulationDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Typo SquattingFor each domain name, count how many other given domains differ from it in exactly one character position.	Medium6	Hash mapString+2	No attempts yet	4s	512 MB	Judgeable
Streaming ServicesGiven the daily release days for two streaming services, find the fewest K-day subscriptions needed so every day has a subscribed service releasing an episode.	Medium6	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
HaikuGiven a set of syllables, decide whether the three input phrases can each be split into syllables so their syllable counts are 5, 7, and 5.	Medium6	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
GazzzuaGiven known future prices over N minutes, buy at most one coin per minute and sell any number at any time, maximizing total profit.	Medium6	GreedyImplementation+2	No attempts yet	1s	256 MB	Judgeable
SubwayEach station belongs to company A or B; find the route from station 0 to M that minimizes transfers first, then travel time, and report both.	Medium6	GraphShortest path+1	No attempts yet	1s	256 MB	Judgeable
Domino PredictionGiven XORs of consecutive domino numbers, answer queries for the XOR of positions x and y, or for the value at y when x holds d.	Medium6	Prefix sumBit manipulation+2	No attempts yet	1s	256 MB	Judgeable
AlehouseGiven n closed time intervals on a weekly circle, pick one interval of length at most k that intersects as many given intervals as possible.	Medium6	IntervalsSliding window+2	No attempts yet	1s	512 MB	Judgeable
One of EachGiven a sequence containing every value 1 to k at least once, find the lexicographically smallest subsequence that includes each value exactly once.	Medium6	GreedyStack+2	No attempts yet	2s	512 MB	Judgeable
Sculptural ProjectGiven a string of work and market days, cancel the fewest days so materials never run out and end at zero.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Gluing PicturesGiven a city string C, find for each friend name the fewest substrings of C that concatenate to form it, or -1 if impossible.	Medium6	Dynamic programmingString matching+2	No attempts yet	0.3s	512 MB	Judgeable
PolygonGiven segment lengths, choose a subset to form a non-degenerate convex polygon (largest side must be smaller than the sum of the rest) and report the maximum total length, or 0 if impossible.	Medium6	GreedySorting+2	No attempts yet	1s	512 MB	Judgeable
Assessing GenomesCompute each DNA string's smallest repeating unit length, then pair the two sets of scores to minimize the sum of squared differences.	Medium6	StringSorting+2	No attempts yet	2s	512 MB	Judgeable
Binary Number GameGiven two binary strings, find the minimum number of single-bit flips (never the leading bit), increments, and decrements to turn the start number into the target.	Medium6	BFSDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Ggeureuda GimgganomGiven N rolls, cut K cm off each end (one end if shorter than 2K, discard if at most K), then find the largest piece length P so the trimmed rolls yield at least M pieces.	Medium6	Binary searchArray+2	No attempts yet	1.5s	1024 MB	Judgeable
Robot AssemblyMaintain a growing set of unions between robot parts and answer, for each query part, how many parts currently belong to its robot.	Medium6	Union-findImplementation+1	No attempts yet	4s	1024 MB	Judgeable
A Water Slide at Catholic University??Given a directed graph, find the minimum number of starting vertices whose reachable sets cover every vertex.	Medium6	GraphBFS+2	No attempts yet	1s	1024 MB	Judgeable
Two Coins UnlimitedTwo coins sit on a grid with walls; each button press slides both coins the same direction, and you must find the fewest presses that drop exactly one coin off the board.	Medium6	BFSGraph+2	No attempts yet	0.5s	512 MB	Judgeable
Bob in WonderlandGiven a tree of N connected links, find the minimum number of link reconnections needed to turn it into a path (each vertex has degree at most two).	Medium6	TreeGreedy+1	No attempts yet	2s	512 MB	Judgeable
Fast ForwardingFind the minimum time to reach position t on a tape when speed can be tripled or divided by three once per second, and playback must end at normal speed.	Medium6	BFSDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Rubber Duck Lovers ClubPick exactly P of N members and assign each a value in [xi, yi] so the P values sum to E, or report that this is impossible.	Medium6	GreedyBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Milk PumpingGiven a graph with per-edge cost and flow, find the 1-to-N path maximizing (bottleneck flow)/(total cost), and print 10^6 times that value truncated.	Medium6	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Milk VisitsGiven a tree with each node labeled G or H, answer queries asking whether the path between two nodes contains at least one node of a given label.	Medium6	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
Swapping PlacesGiven a line of animals where adjacent friend species may swap places, print the alphabetically smallest checkout order that can result.	Medium6	Topological sortGreedy+1	No attempts yet	1s	512 MB	Judgeable
Splitting DNAGiven the lengths of N fragments in order, find the minimum total energy to split the original chain, where each cut costs the current chain length.	Medium6	Dynamic programmingIntervals+2	No attempts yet	1s	512 MB	Judgeable
Gold RushGiven c Oshloobs and the gold price for each of n days, find the maximum Oshloobs at the end of day n, buying and selling gold each day and cashing out at the end.	Medium6	Dynamic programmingGreedy	No attempts yet	2s	512 MB	Judgeable
PasswordCount the Android-style 3x3 patterns whose segment directions match a given string, allowing any segment lengths, with no self-intersection allowed.	Medium6	DFSBacktracking+2	No attempts yet	2s	512 MB	Judgeable
ASLRDRReorder a string with adjacent swaps so it becomes a palindrome, reporting the minimum number of swaps or Impossible.	Medium6	GreedyTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Avoiding SurveillancePlace exactly 3 obstacles on empty cells of an N x N grid so that no teacher can see any student along its row or column.	Medium6	Brute forceBacktracking+2	No attempts yet	2s	256 MB	Judgeable
Weapon EngineeringOn a grid of at most 5 by 5 cells, place L-shaped triominoes (with the corner counted twice) so the covered cells' score is maximized.	Medium6	BacktrackingBrute force+2	No attempts yet	2s	256 MB	Judgeable
Two TeamsChoose the order in which to reveal each team's hidden last-hour problems so that teams A and B swap rank as many times as possible.	Medium6	GreedySorting+1	No attempts yet	2s	512 MB	Judgeable
Mineral 2Throw sticks alternately from left and right; each destroys the first mineral hit, then any cluster left floating falls straight down until it lands.	Medium6	SimulationGraph+2	No attempts yet	1s	512 MB	Judgeable
DeliveriesGiven a tree of warehouses with road lengths, find the fewest stops on the path from S to F when the truck can drive at most T km per charge.	Medium6	TreeGreedy+1	No attempts yet	2s	512 MB	Judgeable
Just Shuffle the InputGiven strings s and t and a cyclic permutation p, find the fewest shuffles of t by p that make it a substring of s, or -1 if impossible.	Medium6	String matchingString+1	No attempts yet	3s	512 MB	Judgeable
Gotta Catch 'Em AllGiven N Pokemon points with types, find the smallest axis-parallel square that contains Pokemon of at least K different types.	Medium6	Binary searchSliding window+1	No attempts yet	2s	512 MB	Judgeable
Football HooliganismPartition a 2 by N grid of team labels into non-overlapping rectangles so that every rectangle is monochromatic, minimizing the number of 1 by 1 rectangles.	Medium6	Dynamic programmingImplementation+2	No attempts yet	2s	512 MB	Judgeable
CatCount how many distinct strings you can form by joining a non-empty suffix of a with a non-empty prefix of b.	Medium6	StringString matching+2	No attempts yet	2s	512 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
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
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
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
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
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
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
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