Interview core

Mediums from real onsites

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Total results3,616 problems

An Unfair Puzzle
Medium6
String, String matching+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Vitcoin Lottery at Moloco (Easy)
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tap Titanz at Moloco (Easy)
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Array Manipulation at Moloco (Hard)
Medium6
Segment tree, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tournament Chart
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shredding Company
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cow Rental Service
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
MooTube (Silver)
Medium6
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Prices
Medium6
Dynamic programming, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fibonacci Number 7
Medium6
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Pepper Wreath
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Thinking Station
Medium6
String, Hash map+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Marble Escape 3
Medium6
BFS, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Farmer Juan is a barista
Medium6
Prefix sum, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Inserting Operators (2)
Medium6
Backtracking, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two teams with the smallest ability gap
Medium6
Bit manipulation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Room Number
Medium6
Brute force, Math+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Stacking dice
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The swimming pool owner
Medium6
Heap, Graph+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Reversing
Medium6
Array, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Directory Traversal
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sejin Virus
Medium6
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Anagrams
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Weekend Trip Plan
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Invader Jina
Medium6
Brute force, Math+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Genetics
Medium6
String, Brute force+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Ukje and Mysophobia
Medium6
Array, Sorting+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Pseudo-Banana Strings
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Building a Spaceship
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Lion Is the King of Travel!!
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hyunwook Is the Parenthesis King!!
Medium6
Stack, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Two Robots
Medium6
Tree, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
1, 2, 3 Sum 6
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
1, 2, 3 Sum 8
Medium6
Dynamic programming, Math+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Elevator 2
Medium6
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Skyscraper MinatoHarukas
Medium6
Math, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Recovery
Medium6
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Down the Pyramid
Medium6
Math, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Fighting Monsters
Medium6
Math, Number theory+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bracket
Medium6
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Lush Gears
Medium6
Dynamic programming, Array+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Drawn and Quartered
Medium6
Math, Bit manipulation+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Club Cheer Volume
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Subway in Seoul
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Noodle Team Contest
Medium6
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chinese ID Number
Medium6
String, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
MST Game
Medium6
Minimum spanning tree, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Meetings
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Medicine Delivery
Medium6
Shortest path, Graph+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Tree Investment
Medium6
Simulation, Implementation+2
No attempts yet
Time limit
0.3s
Memory limit
512 MB
Judgeable
Baby Shark
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Moving Company
Medium6
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Mortal Combat
Medium6
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Birthday Boy
Medium6
Array, Sorting+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Game Night
Medium6
String, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Memory Allocation
Medium6
Intervals, Simulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Circuits
Medium6
Sorting, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Starwars
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Prime Tree - 3
Medium6
Tree, Greedy+2
No attempts yet
Time limit
10s
Memory limit
512 MB
Judgeable
Racing Around the Alphabet
Medium6
Math, Geometry+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Escape
Medium6
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Prime Currency
Medium6
Dynamic programming, Number theory+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Cops and Robbers
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Paper Strips
Medium6
String, Dynamic programming
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
To Tell the Truth
Medium6
Brute force, Math+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Random Index Vectors
Medium6
Two pointers, Hash map+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Piglets and Wolves
Medium6
Simulation, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Marbles
Medium6
Game theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pizza Cutter
Medium6
Math, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Chick's Transformation Is Not Guilty
Medium6
Dynamic programming, Matrix+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Boy Jump
Medium6
Graph, BFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Sequences
Medium6
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Missing Bridges
Medium6
Graph, Union-find+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Chain
Medium6
Stack, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Oblongs and Right Triangles
Medium6
Brute force, Geometry+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Card Game
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
1.2s
Memory limit
512 MB
Judgeable
Linked List
Medium6
Linked list, Array+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Substring Permutation
Medium6
Hash map, Two pointers+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Collecting Stars
Medium6
Greedy, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hazardous Driving
Medium6
Graph, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ebony and Ivory
Medium6
Dynamic programming, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Generalized German Quotation
Medium6
Stack, Implementation+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Liars
Medium6
Hash map, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
JackRabbit Slim
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Arithmetic Progressions
Medium6
Array, Hash map+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Deblo
Medium6
Tree, Bit manipulation+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Circle Cross Stamps
Medium6
Dynamic programming, Greedy+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Colorful Drink
Medium6
Greedy, Binary search+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Watch Where You Step
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hotel Management
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding Crosses
Medium6
Implementation, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Making a Shape
Medium6
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Digit Rearrangement
Medium6
Backtracking, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Breaking a Wall and Moving 4
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Seoul Subway Line 2
Medium6
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
A → B
Medium6
Greedy, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Ball on a Chessboard
Medium6
Graph, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
DFS Special Judge
Medium6
DFS, Tree+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Rectangle Escape
Medium6
BFS, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Minhyuk's Game Party
Medium6
Union-find, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
An Unfair PuzzleGiven two permutations of 1..n, decide whether cyclic rotations and reversals can turn the first into the second, printing good puzzle or bad puzzle.	Medium6	StringString matching+2	No attempts yet	2s	256 MB	Judgeable
Vitcoin Lottery at Moloco (Easy)Order n tickets with prizes w_i and continuation probabilities p_i to maximize the expected sum of collected prizes, breaking ties by the lexicographically smallest permutation.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Tap Titanz at Moloco (Easy)On an n by n black/white board, each tap flips a whole same-color connected region; find the minimum taps to make the board one color.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Array Manipulation at Moloco (Hard)For each position i in a permutation-like array, count how many earlier elements are smaller than A[i], with n up to one million.	Medium6	Segment treeBinary search+2	No attempts yet	2s	512 MB	Judgeable
Tournament ChartParse a knockout bracket given as a string and decide whether the reported win counts for all players can be consistent with some assignment of match winners.	Medium6	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Shredding CompanySplit a digit string into contiguous pieces so their sum is as large as possible without exceeding a target, reporting rejection on ties and error when even the smallest sum is too big.	Medium6	BacktrackingBrute force+2	No attempts yet	2s	512 MB	Judgeable
Cow Rental ServiceChoose for each cow whether to milk it or rent it, matching milk to stores with limited quantity and price, to maximize total cents.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
MooTube (Silver)Given a weighted tree, for each query (k, v) count the vertices whose bottleneck distance (minimum edge on the path) from v is at least k.	Medium6	GraphDFS+1	No attempts yet	2s	512 MB	Judgeable
The PricesChoose for each product a wholesaler to buy it from, paying each visited wholesaler's round-trip cost once, to minimize the total.	Medium6	Dynamic programmingBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Fibonacci Number 7Compute the n-th Fibonacci number modulo 1,000,000,007 for n up to one million.	Medium6	Dynamic programmingMath+1	No attempts yet	1s	512 MB	Judgeable
Pepper WreathGiven a tree whose vertices carry non-negative weights and a cap k, find the minimum number of edges to cut so every resulting component has total weight at most k.	Medium6	TreeDFS+2	No attempts yet	1s	1024 MB	Judgeable
Thinking StationFor each K from 1 to N, split the first N cars into blocks of K (dropping the remainder) and count distinct blocks up to reversal; report the K values with the maximum count.	Medium6	StringHash map+2	No attempts yet	1s	256 MB	Judgeable
Marble Escape 3Tilt a small grid board to roll a red and a blue marble until one falls in the single hole; find the shortest tilt sequence that drops red and not blue, breaking ties lexicographically.	Medium6	BFSSimulation+2	No attempts yet	2s	512 MB	Judgeable
Farmer Juan is a baristaMaintain a grid under range-add rectangle updates and point queries, answering each point query using only earlier updates.	Medium6	Prefix sumMatrix+2	No attempts yet	2s	512 MB	Judgeable
Inserting Operators (2)Insert one of +, -, x, / between each adjacent pair from a limited supply, evaluating left to right with C++14 integer division, and report the largest and smallest results.	Medium6	BacktrackingBrute force+2	No attempts yet	2s	512 MB	Judgeable
Two teams with the smallest ability gapSplit N people into two nonempty teams so the difference between the two teams' pairwise ability sums is minimized, and print that minimum.	Medium6	Bit manipulationBrute force+2	No attempts yet	2s	512 MB	Judgeable
Room NumberFind natural numbers A and B with A + B = N, no leading zeros, and no digit repeated across both numbers, minimizing A.	Medium6	Brute forceMath+2	No attempts yet	1s	256 MB	Judgeable
Stacking dicePartition N dice into the fewest towers, where a tower lists dice top to bottom so the i-th die has at most s_i dice above it.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
The swimming pool ownerGiven an N by M grid of heights, compute how much water the terrain traps, where each cell's water level is the lowest possible maximum height along any path to the border.	Medium6	HeapGraph+2	No attempts yet	2s	128 MB	Judgeable
ReversingGiven prefix or suffix reversals applied to an array, track where the element originally at position K ends up after all operations.	Medium6	ArrayImplementation+2	No attempts yet	2s	512 MB	Judgeable
Directory TraversalGiven a directory tree, choose a directory that minimizes the total length of all relative paths from it to every file.	Medium6	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
Sejin VirusGiven a directed graph of facilities and pipes, find the minimum number of starting nodes from which all nodes are reachable.	Medium6	GraphDFS+1	No attempts yet	1s	512 MB	Judgeable
AnagramsGiven two equal-length uppercase strings A and B, find the minimum total number of cyclic letter increments applied to positions of A so the result is an anagram of B.	Medium6	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Weekend Trip PlanGiven a weighted graph and separate destination and lodging values at each location, find the maximum of w_a + w_b - dist(a, b) over all destination-lodging pairs.	Medium6	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Invader JinaPlace two poison sources on empty cells of an N by M grid so that the maximum Manhattan distance from any village to its nearest source is minimized.	Medium6	Brute forceMath+2	No attempts yet	2s	256 MB	Judgeable
GeneticsGiven N DNA strings of length M, find the one string that differs from every other string in exactly K positions.	Medium6	StringBrute force+2	No attempts yet	2s	1024 MB	Judgeable
Ukje and MysophobiaSort a permutation of 1 to N by repeatedly reversing intervals, using at most N*N reversals to make card i sit at position i.	Medium6	ArraySorting+2	No attempts yet	2s	256 MB	Judgeable
Pseudo-Banana StringsGiven a string of B, A, N, find the minimum number of character replacements that turn it into a concatenation of blocks of the form B+ANANA(NA)*.	Medium6	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Building a SpaceshipPartition the ordered parts into contiguous groups, paying for each group the product of its maximum weight and maximum energy; minimize the total cost.	Medium6	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
The Lion Is the King of Travel!!Given N days and M fixed non-overlapping-or-not travel intervals, choose a subset of disjoint intervals minimizing the longest gap of untraveled days.	Medium6	Binary searchGreedy+2	No attempts yet	2s	512 MB	Judgeable
Hyunwook Is the Parenthesis King!!Given a string of parentheses, find the length of the longest contiguous substring that forms a correct parenthesis string.	Medium6	StackString+2	No attempts yet	2s	512 MB	Judgeable
Two RobotsOn a weighted tree, two robots at given nodes must meet on some edge or its endpoints; find the minimum combined distance traveled.	Medium6	TreeDFS+2	No attempts yet	2s	512 MB	Judgeable
1, 2, 3 Sum 6Count the compositions of n into parts 1, 2, and 3 that read the same forwards and backwards, modulo 1,000,000,009.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	1s	512 MB	Judgeable
1, 2, 3 Sum 8For each n, count the ordered compositions of n into parts 1, 2, 3, reporting the number using an odd count of terms and the number using an even count, each modulo 1,000,000,009.	Medium6	Dynamic programmingMath+1	No attempts yet	1s	512 MB	Judgeable
Elevator 2Each elevator i stops on floors Xi, Xi+Yi, Xi+2Yi, ... Find the fewest elevator rides to travel from floor A to floor B and output one such sequence.	Medium6	BFSGraph+2	No attempts yet	1s	128 MB	Judgeable
Skyscraper MinatoHarukasFor each budget b, find the longest run of consecutive positive integers summing to b and print its first floor and length.	Medium6	MathTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
RecoveryGiven row and column parities of a lost 0/1 matrix, output the matrix with the most ones, and among those the lexicographically smallest row-major string, or -1 if none exists.	Medium6	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable
Down the PyramidCount non-negative integer sequences of length n+1 lying under a given length-n sequence, where each adjacent pair sums to the number above it.	Medium6	MathImplementation+2	No attempts yet	2s	512 MB	Judgeable
Fighting MonstersFind two monsters whose fight to the death leaves the survivor with exactly power 1, and report the starting index and the other index, or impossible.	Medium6	MathNumber theory+2	No attempts yet	2s	512 MB	Judgeable
BracketGiven a bracket pattern with some fixed brackets and some dots, count the ways to fill the dots so the whole string is a balanced bracket sequence.	Medium6	Dynamic programmingCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
Lush GearsPick one model per gear type so the total cost is as close to C as possible without exceeding it, and report the leftover coins.	Medium6	Dynamic programmingArray+1	No attempts yet	2s	512 MB	Judgeable
Drawn and QuarteredA fixed permutation is applied to a string K times; find where each index goes and output the rearranged string.	Medium6	MathBit manipulation+1	No attempts yet	2s	512 MB	Judgeable
Club Cheer VolumeGiven N ideal volumes, find the smallest shout volume D so that at least K members reach satisfaction at least X percent, and print D as an integer or reduced fraction.	Medium6	MathNumber theory+2	No attempts yet	1s	256 MB	Judgeable
Subway in SeoulGiven up to 10 subway lines, each listing stations (0 is the start), find the minimum number of transfers to reach a destination station.	Medium6	GraphBFS+2	No attempts yet	2s	128 MB	Judgeable
Noodle Team ContestGiven each member's pot time and seasoning time, order the members to minimize the total time until all noodles are finished.	Medium6	GreedySorting+1	No attempts yet	2s	512 MB	Judgeable
Chinese ID NumberCheck an 18-character Chinese ID: region code from a given list, birthday in 1900 to 2011, sequence code not 000, then for valid IDs report gender by odd/even sequence code. The checksum is a mod 11 weighted sum of the first 17 digits plus a digit x making the total 1, with x=10 written as 'X'.	Medium6	StringArray+2	No attempts yet	2s	512 MB	Judgeable
MST GameGiven an edge-weighted simple graph and a turn count K, find the MST cost each turn and delete the lightest MST edge after each turn, outputting 0 once the graph has no spanning tree.	Medium6	Minimum spanning treeGraph+2	No attempts yet	2s	512 MB	Judgeable
MeetingsEach person occupies an interval [Si, Ei]; pair up people whose intervals overlap into disjoint pairs and maximize the number of pairs.	Medium6	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Medicine DeliveryFind the fastest route from one settlement to the other along roads, pausing 5 minutes at equipment stations to wash whenever 100 minutes of driving would otherwise be exceeded.	Medium6	Shortest pathGraph+2	No attempts yet	1s	1024 MB	Judgeable
Tree InvestmentTrack trees by age on each cell of an N by N grid and run spring to winter nutrient cycles for K years to count survivors.	Medium6	SimulationImplementation+2	No attempts yet	0.3s	512 MB	Judgeable
Baby SharkOn a grid with fish and a baby shark that eats smaller fish and grows, simulate its BFS-driven meal choices and report the total time spent.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
Moving CompanyGiven counts of items weighing 1 to 5 kg, find the minimum number of 5 kg baskets needed to pack them all.	Medium6	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Mortal CombatSend heroes one at a time to kill the boss, choosing the order that loses the fewest heroes, or report -1 if the boss wins.	Medium6	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Birthday BoyGiven colleagues' birthdays on a non-leap calendar, pick a date not used by anyone that maximizes the gap just before it, breaking ties toward the earliest date after October 27.	Medium6	ArraySorting+2	No attempts yet	1s	512 MB	Judgeable
Game NightGiven a circular arrangement of A, B, and C seats, find the minimum people to move so each team forms one contiguous block.	Medium6	StringSliding window+2	No attempts yet	1s	512 MB	Judgeable
Memory AllocationSimulate first-fit malloc and free over 100,000 memory cells and print requested variable values in command order.	Medium6	IntervalsSimulation+2	No attempts yet	1s	512 MB	Judgeable
CircuitsGiven axis-aligned rectangles, choose two horizontal lines to maximize how many distinct rectangles they touch along a top or bottom side.	Medium6	SortingArray+2	No attempts yet	2s	512 MB	Judgeable
StarwarsGiven human systems, bases, and directed labeled wormholes, decide whether a nonhuman start yields a certificate sequence matching one produced by some human start reaching any base.	Medium6	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
Prime Tree - 3Relabel a tree's vertices with 1 to n to minimize edges whose endpoints share a prime factor, and output the labeling for every test case.	Medium6	TreeGreedy+2	No attempts yet	10s	512 MB	Judgeable
Racing Around the AlphabetCompute the running time for a player who follows a message's characters around 28 marks on a circle, using the shortest arc between marks and 1 second per pickup.	Medium6	MathGeometry+2	No attempts yet	2s	512 MB	Judgeable
EscapeFind the fewest presses of A (add 1) and B (double then cut the leading digit) turning N into G without passing 99999 in T steps, or report impossible.	Medium6	BFSGraph+1	No attempts yet	1s	256 MB	Judgeable
Prime CurrencyCount the unordered ways to make N with unlimited primes, using a coin-change DP, and print the count modulo 123,456,789.	Medium6	Dynamic programmingNumber theory+1	No attempts yet	1s	256 MB	Judgeable
Cops and RobbersBlock the robbers' escape from the bank at minimum cost by barricading priced terrain cells, treating it as a minimum vertex cut on the grid graph.	Medium6	GraphShortest path+2	No attempts yet	5s	512 MB	Judgeable
Paper StripsGiven a lowercase string, find the fewest cuts needed so that the cut pieces can be rearranged into a bitonic string.	Medium6	StringDynamic programming	No attempts yet	2s	512 MB	Judgeable
To Tell the TruthGiven n people each claiming the true count lies in [a,b], find the largest consistent truth-teller count or -1 if none exists.	Medium6	Brute forceMath+1	No attempts yet	2s	512 MB	Judgeable
Random Index VectorsMerge two sparse signed index lists to output their element-wise sum, product, and each list rotated left by k with wraparound.	Medium6	Two pointersHash map+2	No attempts yet	2s	512 MB	Judgeable
Piglets and WolvesGiven an N by M grid with grassland, ice, mountains and wolf starts, simulate wolf sliding on ice and mark unreachable grassland cells as P.	Medium6	SimulationBFS+2	No attempts yet	1s	256 MB	Judgeable
MarblesTreat marbles as Wythoff/Nim heap coordinates and compute Sprague-Grundy values to decide if the first player wins.	Medium6	Game theoryMath+2	No attempts yet	2s	512 MB	Judgeable
Pizza CutterCount the pieces made by H rightward and V upward cuts whose endpoints are given, using Euler's formula and inversion counting of crossing pairs.	Medium6	MathCombinatorics+2	No attempts yet	2s	512 MB	Judgeable
The Chick's Transformation Is Not GuiltyEach chick lays one egg daily and each egg hatches K days later. Find the chick count after N days modulo 100000007.	Medium6	Dynamic programmingMatrix+1	No attempts yet	1s	512 MB	Judgeable
Boy JumpGiven a grid maze and three start cells, find the meeting cell minimizing the maximum shortest-path distance from the three starts, and count all optimal cells or report -1 if unreachable.	Medium6	GraphBFS+2	No attempts yet	1s	512 MB	Judgeable
SequencesCount non-decreasing length-n sequences over 1 to m where each integer appears at most k times. Use DP over the largest value and its count.	Medium6	Dynamic programmingCombinatorics+1	No attempts yet	2s	512 MB	Judgeable
Missing BridgesFind the fewest new bridges so that every bridge can be crossed once in a closed walk back to the start, and print those bridges.	Medium6	GraphUnion-find+1	No attempts yet	2s	512 MB	Judgeable
ChainFor each position, repeatedly jump to the first strictly greater element on its right and report the length of that chain.	Medium6	StackDynamic programming+1	No attempts yet	2s	512 MB	Judgeable
Oblongs and Right TrianglesCount 4-black-point sets forming a non-square rectangle and 3-white-point sets forming a right triangle, disjoint and with positive area.	Medium6	Brute forceGeometry+2	No attempts yet	1s	256 MB	Judgeable
Card GameMinsu holds M distinct blue cards and must answer each of K plays by discarding the smallest blue card larger than Cheolsu's card, or answering 0 when none exists.	Medium6	Binary searchGreedy+2	No attempts yet	1.2s	512 MB	Judgeable
Linked ListMaintain a permutation of 1..N under slide(a,b) moves (move a to just after b), reporting how far a moves each time and printing the final list.	Medium6	Linked listArray+2	No attempts yet	1s	512 MB	Judgeable
Substring PermutationGiven strings S and P, decide whether some permutation of P is a substring of some permutation of S.	Medium6	Hash mapTwo pointers+1	No attempts yet	1s	512 MB	Judgeable
Collecting StarsGiven n stars with times and unlock thresholds, pick k in some order respecting the thresholds and minimize the total time.	Medium6	GreedyBinary search+2	No attempts yet	2s	512 MB	Judgeable
Hazardous DrivingGiven an undirected weighted graph, find an S to E route minimizing its maximum edge hazard, and among those the minimum total length.	Medium6	GraphBinary search+2	No attempts yet	2s	512 MB	Judgeable
Ebony and IvoryAssign fingers 1 to 5 to a monophonic piano passage given four ergonomic transition tables and output the minimum total difficulty of all adjacent intervals.	Medium6	Dynamic programmingImplementation	No attempts yet	2s	512 MB	Judgeable
Generalized German QuotationGiven a string of << and >> marks, decide whether it forms nested conventional or reversed German quotes and rewrite every mark as an opening [ or closing ], or report that none exists.	Medium6	StackImplementation+1	No attempts yet	3s	512 MB	Judgeable
LiarsGiven each person's claimed range for the truth-teller count, find the maximum possible number of truth-tellers within any consistent assignment.	Medium6	Hash mapPrefix sum+1	No attempts yet	1s	512 MB	Judgeable
JackRabbit SlimGiven sorted distinct carrot positions on a line, Slim repeatedly jumps to the nearest remaining carrot, breaking ties to the right; find the sum of total distances over all possible starting carrots.	Medium6	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Arithmetic ProgressionsGiven up to 5000 distinct numbers, find the length of the longest subset that forms an arithmetic progression.	Medium6	ArrayHash map+1	No attempts yet	5s	512 MB	Judgeable
DebloGiven a tree with numbers on its nodes, add up the XOR of every node-value along every path between two nodes, counting single-node paths too.	Medium6	TreeBit manipulation+2	No attempts yet	1s	512 MB	Judgeable
Circle Cross StampsGiven a row of O and X marks printed by single circles, single crosses, and two-mark circle-cross stamps in either orientation, find the largest possible count of circle-cross stamps.	Medium6	Dynamic programmingGreedy+1	No attempts yet	2s	512 MB	Judgeable
Colorful DrinkGiven colored liquids with densities and a top-to-bottom list of requested color layers, decide whether one liquid per layer has strictly decreasing densities.	Medium6	GreedyBinary search+2	No attempts yet	2s	512 MB	Judgeable
Watch Where You StepFind the maximum number of new one-way sidewalks you can add to a zoo graph without creating any new reachability between attractions.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Hotel ManagementEach room belongs to exactly two switches; find whether pressing some subset of switches turns every room's lock state to open.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Finding CrossesGiven a grid of stars and dots, decide whether it can be covered exactly by overlapping plus-shaped crosses, and if so output which crosses to draw.	Medium6	ImplementationBrute force+2	No attempts yet	2s	512 MB	Judgeable
Making a ShapeIn a grid of 0s and 1s, find the largest connected group of 1s obtainable by flipping exactly one 0 cell to 1.	Medium6	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
Digit RearrangementGiven A and B, rearrange the digits of A (no leading zero) to build the largest permutation that is still strictly less than B, or print -1.	Medium6	BacktrackingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Breaking a Wall and Moving 4For each wall cell in an N by M binary grid, break it and print the size of the reachable open region modulo 10, leaving empty cells as 0.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Seoul Subway Line 2Given a connected graph with N vertices and N edges (exactly one cycle), find each vertex's distance to the unique cycle.	Medium6	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
A → BUsing the operations double a number or append a digit 1, find the minimum number of steps to turn A into B, or report that it is impossible.	Medium6	GreedyBFS+2	No attempts yet	2s	512 MB	Judgeable
Ball on a ChessboardEach cell of an R by C board holds a distinct number; every ball rolls to the smallest neighbor until it reaches a local minimum, and we must count how many balls stop on each cell.	Medium6	GraphDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
DFS Special JudgeGiven a tree and a permutation of its vertices, decide whether that permutation can be the DFS visit order starting from vertex 1.	Medium6	DFSTree+2	No attempts yet	2s	512 MB	Judgeable
Rectangle EscapeA rectangle slides on a grid with walls; find the shortest sequence of unit moves taking its top-left cell from start to finish.	Medium6	BFSPrefix sum+2	No attempts yet	2s	512 MB	Judgeable
Minhyuk's Game PartyGiven people with game choices and cables added one at a time, report after which cable each game's buyers all become connected, or 0 or -1.	Medium6	Union-findGraph+2	No attempts yet	2s	512 MB	Judgeable