Interview core

Mediums from real onsites

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Still being built. Things may change

Total results3,612 problems

Reorganizing Bus Routes
Medium6
Sorting, Intervals+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
String Decompression
Medium6
String, Implementation+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Children and Gift Boxes
Medium6
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Picky Children and Gift Boxes
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Forming Badminton Doubles Teams
Medium6
Sorting, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Two-Step Shortest Path 2
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Enemy of My Enemy
Medium6
Union-find, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Matryoshka
Medium6
Dynamic programming, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Snowman
Medium6
Greedy, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Teacher Sorting
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Lonely Photo
Medium6
String, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Walking Home
Medium6
Dynamic programming, Matrix+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tire Tug
Medium6
Dynamic programming, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Plates
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Algorithm Class - Selection Sort 6
Medium6
Sorting, Implementation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Stable Wall
Medium6
Graph, Topological sort+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Perfect Subarray
Medium6
Prefix sum, Hash map+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Boring Numbers
Medium6
Dynamic programming, Math+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Food Stalls
Medium6
Heap, Sorting+1
No attempts yet
Time limit
30s
Memory limit
1024 MB
Judgeable
Cherries Mesh
Medium6
Minimum spanning tree, Union-find+2
No attempts yet
Time limit
15s
Memory limit
1024 MB
Judgeable
Teach Me
Medium6
Bit manipulation, Combinatorics+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Lucky Dip
Medium6
Dynamic programming, Probability+2
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
String Splitting
Medium6
Dynamic programming, String+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Product Triplets
Medium6
Array, Hash map+2
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Math Encoder
Medium6
Combinatorics, Math+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Centrists
Medium6
String, Sorting+2
No attempts yet
Time limit
20s
Memory limit
1024 MB
Judgeable
Baby Hongyoon
Medium6
Bit manipulation, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Inconstant Ordering
Medium6
Greedy, String+2
No attempts yet
Time limit
10s
Memory limit
1024 MB
Judgeable
Algorithm Class - Insertion Sort 6
Medium6
Array, Hash map+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Algorithm Class - Quick Sort 3
Medium6
Sorting, Divide and conquer+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Shiritori
Medium6
Graph, DFS
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Stairs
Medium6
Dynamic programming, Prefix sum+2
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Factorial (Factorial)
Medium6
Number theory, Math+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Elephant Handler (Route)
Medium6
Graph, Shortest path+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Meeting
Medium6
Sorting, Intervals+2
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Interpretation
Medium6
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Broken Tree
Medium6
Tree, DFS+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rectangles
Medium6
Hash map, Geometry+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
АВТОБУСИ
Medium6
Math, Number theory+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
School Concert
Medium6
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Number of zeros
Medium6
Math, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
МАГАЗИН
Medium6
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Counting substrings
Medium6
Backtracking, Combinatorics+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
123456789 Points
Medium6
Math, Binary search+2
No attempts yet
Time limit
0.2s
Memory limit
512 MB
Judgeable
Say xor NO!
Medium6
Trie, Bit manipulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Algorithm Class - Matrix Path Problem 3
Medium6
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Matrix Path Problem 6
Medium6
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Algorithm Class - Matrix Path Problem 7
Medium6
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Card Game
Medium6
Brute force, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Barista Power
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
I Want to Receive at Least a Special Prize
Medium6
Divide and conquer, Recursion+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Bottleneck Travelling Salesman Problem (Small)
Medium6
Graph, Brute force+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Zombie Virus
Medium6
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Road Information
Medium6
Prefix sum, Hash map+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Correct Parentheses
Medium6
String, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pinned Files
Medium6
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Square Pool
Medium6
Binary search, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sleeping in Class
Medium6
Array, Prefix sum+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Day Streak
Medium6
Two pointers, Sorting+1
No attempts yet
Time limit
4s
Memory limit
512 MB
Judgeable
Billboard Announcements
Medium6
Intervals, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Animal Observation (easy version)
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Moving Cells
Medium6
Dynamic programming, Sliding window
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Maximum Rest
Medium6
Binary search, Dynamic programming+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Center Stage
Medium6
Segment tree, Array
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Similar Spacing
Medium6
Dynamic programming, Brute force
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Unifying Values
Medium6
Prefix sum, Hash map+2
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Land Purchase
Medium6
Prefix sum, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Music Playlist
Medium6
Dynamic programming, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Chain Reactions
Medium6
Tree, Greedy+1
No attempts yet
Time limit
Not set
Memory limit
1024 MB
Judgeable
Controlled Inflation
Medium6
Dynamic programming, Array+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
TOO EASY Cookie Run
Medium6
Binary search, Two pointers+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Wooden Planks
Medium6
Sorting, Intervals+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Flexible Ficus
Medium6
Bit manipulation, Greedy+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Superheroes
Medium6
Stack, Intervals+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Cynical Frog
Medium6
BFS, Graph+1
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Rafting Trip
Medium6
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Transparency
Medium6
Graph, Shortest path+1
No attempts yet
Time limit
6s
Memory limit
1024 MB
Judgeable
Special Prize
Medium6
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Connected Car Experiment
Medium6
Graph, BFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Count of Integers Called Until the End
Medium6
Dynamic programming, Game theory+1
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Watt
Medium6
Segment tree, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Sticks
Medium6
Sorting, Segment tree+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Tree MEX
Medium6
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Gimbap
Medium6
Sorting, Prefix sum
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Toy Mixing
Medium6
Dynamic programming, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Choosing a Room
Medium6
Shortest path, Graph
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
One Dimensional
Medium6
Divide and conquer, Recursion+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
K-gap Subsequence
Medium6
Dynamic programming, Segment tree+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Mountain View
Medium6
Sliding window, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bouncing Bunnies
Medium6
BFS, Hash map+1
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Build a Staircase (Large)
Medium6
Dynamic programming, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Codepowers
Medium6
Prefix sum, Sorting+1
No attempts yet
Time limit
1.234s
Memory limit
1024 MB
Judgeable
Match of the Millennium
Medium6
Sorting, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Shuffle Game
Medium6
Dynamic programming, String
No attempts yet
Time limit
1.5s
Memory limit
1024 MB
Judgeable
Nonogram
Medium6
Dynamic programming, Prefix sum+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Avant-garde Autocorrect
Medium6
Trie, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cucumber
Medium6
Array, Stack+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Frizura
Medium6
Union-find, Sorting+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Suspects and Witnesses
Medium6
Graph, BFS
No attempts yet
Time limit
40s
Memory limit
1024 MB
Judgeable
Tax Collectors
Medium6
Tree, Dynamic programming
No attempts yet
Time limit
9s
Memory limit
1024 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Reorganizing Bus RoutesMerge overlapping intervals into their union, keeping the cheaper fare, then output the surviving intervals sorted by start.	Medium6	SortingIntervals+2	No attempts yet	2s	1024 MB	Judgeable
String DecompressionGiven patterns mapped to uppercase letters and a compressed string, expand it and print characters S through E of the original string.	Medium6	StringImplementation+2	No attempts yet	1s	1024 MB	Judgeable
Children and Gift BoxesGiven N boxes of gifts and M children with desired amounts in a fixed order, decide if each child in turn can take their amount from the currently fullest box.	Medium6	GreedyHeap+2	No attempts yet	1s	1024 MB	Judgeable
Picky Children and Gift BoxesEach child in order takes w_i gifts from the box ranked b_i-th largest by current count; decide if every child can succeed.	Medium6	SortingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Forming Badminton Doubles TeamsPartition some people into groups of four to minimize the total skill gap per group, and list anyone left out; output any valid choice.	Medium6	SortingDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Two-Step Shortest Path 2Given an undirected weighted graph, find the shortest distance from X to Z that passes through at least one of P given intermediate vertices.	Medium6	GraphShortest path+2	No attempts yet	1s	512 MB	Judgeable
Enemy of My EnemyGiven friend and enemy relations between people, derive implied relations using the enemy-of-my-enemy rule, then answer queries with Friend, Enemy, Unknown, or Error.	Medium6	Union-findGraph+2	No attempts yet	1s	512 MB	Judgeable
MatryoshkaPartition N dolls into groups, each group being a consecutive range of distinct sizes, and maximize the sum over groups of (largest size) times (group size).	Medium6	Dynamic programmingSorting+2	No attempts yet	1s	1024 MB	Judgeable
SnowmanGiven a string of section classes and a length k, find the lexicographically smallest length-k string you can form by walking on the string with possible repeats.	Medium6	GreedyString+2	No attempts yet	1s	512 MB	Judgeable
Teacher SortingGiven an array, decide whether it can be sorted by disjoint swaps (each index used at most once) and output such a swap sequence.	Medium6	SortingGreedy+2	No attempts yet	1s	512 MB	Judgeable
Lonely PhotoCount substrings of length at least three that contain exactly one G or exactly one H in a binary string of up to 5*10^5 characters.	Medium6	StringCombinatorics+2	No attempts yet	2s	1024 MB	Judgeable
Walking HomeCount monotone grid paths from top-left to bottom-right that avoid haybales and change direction at most K times, with K at most 3.	Medium6	Dynamic programmingMatrix+2	No attempts yet	2s	1024 MB	Judgeable
Tire TugDistribute M students across N tires, beating the opponent's count on chosen tires to maximize the score gap and report whether a win, draw, or loss is the best outcome.	Medium6	Dynamic programmingGreedy+2	No attempts yet	1s	1024 MB	Judgeable
PlatesChoose exactly P plates from N stacks of K plates, where taking a plate requires taking every plate above it, to maximize total beauty.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	20s	1024 MB	Judgeable
Algorithm Class - Selection Sort 6Given distinct arrays A and B, decide whether A equals B at some moment during selection sort, including before any swap.	Medium6	SortingImplementation+2	No attempts yet	3s	512 MB	Judgeable
Stable WallGiven a rectangular grid of letters where each letter is one polyomino, find an order in which the polyominoes can be placed so every piece is always supported from below, or report that no such order exists.	Medium6	GraphTopological sort+2	No attempts yet	20s	1024 MB	Judgeable
Perfect SubarrayCount the contiguous non-empty subarrays whose total sum is a perfect square, with array values between -100 and 100.	Medium6	Prefix sumHash map+2	No attempts yet	Not set	1024 MB	Judgeable
Boring NumbersCount numbers in [L, R] whose digits alternate odd, even, odd, even by position, using a digit-DP style prefix count.	Medium6	Dynamic programmingMath+2	No attempts yet	20s	1024 MB	Judgeable
Food StallsPick one warehouse spot and K stall spots from N candidates to minimize total cost, where each stall also pays its distance to the warehouse.	Medium6	HeapSorting+1	No attempts yet	30s	1024 MB	Judgeable
Cherries MeshEach pair of cherries is joined by a red strand of weight 2 or, if listed, a black strand of weight 1. Keep a spanning tree of minimum total weight.	Medium6	Minimum spanning treeUnion-find+2	No attempts yet	15s	1024 MB	Judgeable
Teach MeEach employee knows up to 5 skills. Count ordered pairs (i, j) where employee i knows some skill that employee j does not.	Medium6	Bit manipulationCombinatorics+2	No attempts yet	40s	1024 MB	Judgeable
Lucky DipWith N items in a bag and up to K redips, compute the expected value of the final item under the optimal stopping rule.	Medium6	Dynamic programmingProbability+2	No attempts yet	Not set	1024 MB	Judgeable
String SplittingCount the ways to cut a digit string into K nonempty contiguous pieces so that no piece starts with a 0 (the piece "0" alone is allowed).	Medium6	Dynamic programmingString+2	No attempts yet	1s	512 MB	Judgeable
Product TripletsCount index triplets where one value equals the product of the other two, handling zeros and duplicate values.	Medium6	ArrayHash map+2	No attempts yet	40s	1024 MB	Judgeable
Math EncoderGiven a sorted list, sum the difference between the largest and smallest element over all non-empty subsets, modulo 1000000007.	Medium6	CombinatoricsMath+2	No attempts yet	20s	1024 MB	Judgeable
CentristsGiven three distinct equal-length strings, decide for each whether some alphabet ordering makes that string the median when the three are sorted lexicographically.	Medium6	StringSorting+2	No attempts yet	20s	1024 MB	Judgeable
Baby HongyoonFind a contiguous subarray whose bitwise OR equals K, or report that none exists.	Medium6	Bit manipulationTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
Inconstant OrderingGiven block sizes, build the alphabetically smallest string starting with A where letters strictly increase in odd blocks and strictly decrease in even blocks.	Medium6	GreedyString+2	No attempts yet	10s	1024 MB	Judgeable
Algorithm Class - Insertion Sort 6Given arrays A and B, decide whether the array A ever equals B at any moment while insertion sort sorts A in ascending order.	Medium6	ArrayHash map+1	No attempts yet	3s	512 MB	Judgeable
Algorithm Class - Quick Sort 3Simulate the given quicksort (Lomuto partition, last element as pivot) on array A and report whether any intermediate state equals array B.	Medium6	SortingDivide and conquer+2	No attempts yet	1s	512 MB	Judgeable
ShiritoriOrder all N ten-digit words so each word begins with the last two-digit character of the previous word, choosing the dictionary-smallest valid sequence.	Medium6	GraphDFS	No attempts yet	5s	1024 MB	Judgeable
StairsCount the increasing sequences of steps from 1 to N whose total height difference is at most P, modulo 1234567.	Medium6	Dynamic programmingPrefix sum+2	No attempts yet	1.5s	1024 MB	Judgeable
Factorial (Factorial)Given n up to 1e8, find the smallest m such that m! is divisible by n.	Medium6	Number theoryMath+2	No attempts yet	0.5s	1024 MB	Judgeable
Elephant Handler (Route)Find the cheapest path from booth 1 to booth 2 in a geometric graph where each turn at a booth must not form an acute angle with the incoming road.	Medium6	GraphShortest path+2	No attempts yet	1s	1024 MB	Judgeable
MeetingEach member gives intervals during which they can attend if the meeting starts inside; find the start time covered by the most members' intervals.	Medium6	SortingIntervals+2	No attempts yet	6s	1024 MB	Judgeable
InterpretationGiven a string of 0s and 1s of length up to 300, count the valid bracket strings that encode to it, where each matched pair is written as 01 or 10.	Medium6	Dynamic programmingString	No attempts yet	1s	512 MB	Judgeable
Broken TreeGiven a tree whose edges are oriented, flip as few edges as possible so that some vertex can reach every other vertex.	Medium6	TreeDFS+2	No attempts yet	1s	512 MB	Judgeable
RectanglesCount how many distinct rectangles have all four vertices among N given lattice points.	Medium6	Hash mapGeometry+2	No attempts yet	2s	1024 MB	Judgeable
АВТОБУСИCount multiples of lcm(a,b,c) that fall inside day d's time window [dt, dt + t - 1], given three bus periods a, b, c.	Medium6	MathNumber theory+2	No attempts yet	1s	1024 MB	Judgeable
School ConcertGiven K burners with different speeds and N discs to burn, find the minimum time to finish all discs when each burner works continuously.	Medium6	Binary searchGreedy+2	No attempts yet	1s	1024 MB	Judgeable
Number of zerosGiven N and K, compute the binomial coefficient C(N,K) and count how many zero digits appear in its decimal representation.	Medium6	MathCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
МАГАЗИНSplit the given item prices across receipts so that on each receipt the floor(size/k) cheapest items are free, minimizing the total paid.	Medium6	GreedySorting+2	No attempts yet	1s	1024 MB	Judgeable
Counting substringsCount the distinct strings that can be built from some subset of the distinct letters of S and that contain P as a contiguous substring.	Medium6	BacktrackingCombinatorics+2	No attempts yet	1s	1024 MB	Judgeable
123456789 PointsGiven N notes and a target score S, find counts of Perfect, Great, Good judgments giving exactly S, or report -1.	Medium6	MathBinary search+2	No attempts yet	0.2s	512 MB	Judgeable
Say xor NO!Count the pairs of numbers from two lists whose bitwise XOR is smaller than K.	Medium6	TrieBit manipulation	No attempts yet	1s	1024 MB	Judgeable
Algorithm Class - Matrix Path Problem 3Given an n by n grid of positive integers, find the maximum right/down path score from (1,1) to (n,n) that passes through a given cell, and the maximum that avoids it.	Medium6	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Matrix Path Problem 6Given an n x n grid of positive integers and a set of P cells, find the maximum sum along a right/down path from (1,1) to (n,n) that visits every listed cell, or -1 if impossible.	Medium6	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Algorithm Class - Matrix Path Problem 7Given an n by n grid of 1s and 2s and a set of marked cells, find the maximum-sum right/down path from top-left to bottom-right, and among such paths the one visiting the most marked cells.	Medium6	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Card GameGiven Bob's row of digits and Alice's digits, find the largest number Alice can form (using at least one card) that is smaller than both readings of Bob's row.	Medium6	Brute forceGreedy+2	No attempts yet	1s	512 MB	Judgeable
Barista PowerIn a grid maze, find the shortest path from the top-left to the bottom-right, where you may clear all walls along one straight row or column direction at most once.	Medium6	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
I Want to Receive at Least a Special PrizeGiven an N x N grid of distinct numbers (N a power of two), recursively pick the second smallest survivor of each quadrant and output the final number.	Medium6	Divide and conquerRecursion+2	No attempts yet	1s	512 MB	Judgeable
Bottleneck Travelling Salesman Problem (Small)Given a small directed weighted graph, find a Hamiltonian cycle minimizing the largest edge cost on the cycle, and output that cost plus one optimal tour.	Medium6	GraphBrute force+2	No attempts yet	1s	1024 MB	Judgeable
Zombie VirusTwo viruses spread one cell per hour from fixed sources on a grid; when both reach a cell within the same hour, virus 3 forms there. Count final cells of each type.	Medium6	BFSGraph+2	No attempts yet	2s	1024 MB	Judgeable
Road InformationCount contiguous substrings of a string over T, G, F, P in which every character occurs a number of times divisible by 3.	Medium6	Prefix sumHash map+2	No attempts yet	1s	1024 MB	Judgeable
Correct ParenthesesCount how many single-character deletions from a bracket string leave a correct balanced parenthesis sequence.	Medium6	StringPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Pinned FilesGiven a start and target ordering of pinned and unpinned files, find the minimum number of pin/unpin toggles that transforms one into the other.	Medium6	Dynamic programmingArray+2	No attempts yet	1s	1024 MB	Judgeable
Square PoolGiven an N by N yard with T tree cells, find the side length of the largest axis-aligned square that contains no tree.	Medium6	Binary searchPrefix sum+2	No attempts yet	1s	1024 MB	Judgeable
Sleeping in ClassCombine adjacent entries of an array so all resulting values are equal, using the fewest merges.	Medium6	ArrayPrefix sum+2	No attempts yet	2s	1024 MB	Judgeable
Day StreakGiven solve times and a day length m, choose a shift t from 0 to m-1 to maximize the longest run of consecutive days with at least one solve.	Medium6	Two pointersSorting+1	No attempts yet	4s	512 MB	Judgeable
Billboard AnnouncementsEach billboard exists from day S_i until the next multiple of T; find the fewest visit days so every billboard is seen at least once.	Medium6	IntervalsGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Animal Observation (easy version)Place alternating red and blue k-wide camera windows over n days to maximize animals seen, where a cell watched by both cameras on the same day counts once.	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	3s	512 MB	Judgeable
Moving CellsEach column has one black segment that can be shifted up or down so that neighboring columns overlap. Find the minimum total number of shifts.	Medium6	Dynamic programmingSliding window	No attempts yet	1s	512 MB	Judgeable
Maximum RestChoose workdays, each capped at W_i, so total work reaches M while the smallest gap between chosen workdays is as large as possible.	Medium6	Binary searchDynamic programming+1	No attempts yet	2s	1024 MB	Judgeable
Center StageGiven an array with point updates, find for each range query the maximum of A_b - A_a - A_c over indices a < b < c inside the range.	Medium6	Segment treeArray	No attempts yet	2s	512 MB	Judgeable
Similar SpacingPick K of N sites on a road so that the largest gap minus the smallest gap between adjacent chosen sites is as small as possible.	Medium6	Dynamic programmingBrute force	No attempts yet	2s	1024 MB	Judgeable
Unifying ValuesCount the ways to split a sequence of N integers into two or more contiguous parts with equal sums, modulo 1,000,000,007.	Medium6	Prefix sumHash map+2	No attempts yet	0.5s	1024 MB	Judgeable
Land PurchaseGiven an r by s grid of cell prices and two numbers a and b, find the nonempty rectangle whose total price minimizes \|x-a\| + \|x-b\|.	Medium6	Prefix sumTwo pointers+1	No attempts yet	2s	512 MB	Judgeable
Music PlaylistFind the maximum sum of preference values when Mingyu can jump back to an earlier song at most two times, with no song heard three or more times.	Medium6	Dynamic programmingGreedy	No attempts yet	1s	1024 MB	Judgeable
Chain ReactionsGiven modules that each point to a lower-indexed module or the abyss, find the maximum sum of chain-reaction maxima over all orders of triggering the initiators.	Medium6	TreeGreedy+1	No attempts yet	Not set	1024 MB	Judgeable
Controlled InflationGiven customers whose products must be visited in customer order from a pump starting at 0, find the fewest up and down presses needed to hit every target pressure.	Medium6	Dynamic programmingArray+1	No attempts yet	5s	1024 MB	Judgeable
TOO EASY Cookie RunFind the smallest X added to every stage so that at least K contiguous sections have a sum of at least M.	Medium6	Binary searchTwo pointers+1	No attempts yet	2s	1024 MB	Judgeable
Wooden PlanksGiven vertical logs, find the lowest horizontal cut line where the total length of the shorter pieces equals k, or report -1 if none exists.	Medium6	SortingIntervals+1	No attempts yet	1.5s	1024 MB	Judgeable
Flexible FicusGiven a tree with node values F_i, keep at least k nodes in one connected piece and maximize the bitwise AND of their values.	Medium6	Bit manipulationGreedy+2	No attempts yet	1s	1024 MB	Judgeable
SuperheroesGiven skyscraper heights and hero positions, count the skyscrapers no hero can jump to, and find how many heroes can be removed without changing that count.	Medium6	StackIntervals+1	No attempts yet	2s	1024 MB	Judgeable
Cynical FrogFind the fewest jumps from the start cell to home on a grid where each cell fixes a jump length, with one skip that lets the frog move any distance in a straight line.	Medium6	BFSGraph+1	No attempts yet	1.5s	1024 MB	Judgeable
Rafting TripGiven a grid of river arrows and sightseeing spots, find the start cell whose raft path passes the most distinct spots adjacent to it.	Medium6	GraphDFS+1	No attempts yet	1s	1024 MB	Judgeable
TransparencyGiven a station graph with uppercase and lowercase edge labels, find the shortest pair of distinct accepted strings whose uppercase letters match, or report -1.	Medium6	GraphShortest path+1	No attempts yet	6s	1024 MB	Judgeable
Special PrizeChoose M special-prize works so that the top K judge scores among the rest get main prizes, maximizing the sum of host scores over all winners.	Medium6	SortingGreedy+2	No attempts yet	2s	1024 MB	Judgeable
Connected Car ExperimentGiven N cars on a line with positions and fuel, find every car that can be connected to the IoT after car S is connected first.	Medium6	GraphBFS+1	No attempts yet	2s	1024 MB	Judgeable
Count of Integers Called Until the EndTwo players alternately call integers from a window of size k, avoiding forbidden values, and the task is to output the total number of calls under the win and lose rules.	Medium6	Dynamic programmingGame theory+1	No attempts yet	3s	512 MB	Judgeable
WattGiven an array, handle range-assign updates and count the contiguous subarrays with an even sum inside a query interval.	Medium6	Segment treePrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
SticksCount the pairs of red horizontal and blue vertical sticks that cross or touch, given up to 500000 sticks with coordinates up to 10^6.	Medium6	SortingSegment tree+1	No attempts yet	2s	1024 MB	Judgeable
Tree MEXGiven a rooted tree with vertex values, print for each vertex the smallest non-negative integer missing from its subtree.	Medium6	TreeDFS+1	No attempts yet	2s	1024 MB	Judgeable
GimbapPick intervals so that one chosen interval contains all the others, and find the maximum total of their values.	Medium6	SortingPrefix sum	No attempts yet	3s	1024 MB	Judgeable
Toy MixingGiven N sequences of length M that cannot be split, find the order to join them so the concatenated sequence has the largest maximum subarray sum.	Medium6	Dynamic programmingBit manipulation+1	No attempts yet	1s	256 MB	Judgeable
Choosing a RoomGiven a graph with random edge weights, find all rooms from which some walk to school (vertex 1) has expected total time at most T.	Medium6	Shortest pathGraph	No attempts yet	2s	1024 MB	Judgeable
One DimensionalBuild a permutation of 1 to N where no element sits between two others at the average of their values.	Medium6	Divide and conquerRecursion+1	No attempts yet	1s	512 MB	Judgeable
K-gap SubsequenceFind the length of the longest subsequence in which every pair of consecutive elements differs by at least k.	Medium6	Dynamic programmingSegment tree+1	No attempts yet	1s	1024 MB	Judgeable
Mountain ViewGiven a piecewise linear mountain outline and a camera width W, find the maximum average elevation over any window of width W.	Medium6	Sliding windowPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Bouncing BunniesFind the fewest jumps from hill 1 to hill n where each jump changes temperature and humidity by the same amount, or report -1 if impossible.	Medium6	BFSHash map+1	No attempts yet	5s	1024 MB	Judgeable
Build a Staircase (Large)Given N column heights, find the fewest columns to change so that every pair of adjacent columns differs in height by at most 1.	Medium6	Dynamic programmingImplementation	No attempts yet	2s	512 MB	Judgeable
CodepowersGiven an initial rating X and per-round changes A, count how many ratings in each query range [l, r) fall below K.	Medium6	Prefix sumSorting+1	No attempts yet	1.234s	1024 MB	Judgeable
Match of the MillenniumGiven piles s_i and ratios p_i, find the fewest add or remove moves so every pile becomes a positive integer multiple of its p_i.	Medium6	SortingMath	No attempts yet	2s	1024 MB	Judgeable
Shuffle GameGiven deck X and two decks P1 and P2, find the maximum LCS length between X and any interleaving of P1 and P2.	Medium6	Dynamic programmingString	No attempts yet	1.5s	1024 MB	Judgeable
NonogramCount the ways to color one nonogram row so its runs match the hint, given cells already marked as must-color (O) or must-stay-empty (X).	Medium6	Dynamic programmingPrefix sum+1	No attempts yet	2s	1024 MB	Judgeable
Avant-garde AutocorrectGiven a frequency-ranked dictionary and a message, find the fewest key presses per word when autocomplete with tab, backspace, and single letters are allowed.	Medium6	TrieDynamic programming+1	No attempts yet	1s	1024 MB	Judgeable
CucumberCount the contiguous subarrays of a sequence whose maximum and minimum differ by an even number.	Medium6	ArrayStack+1	No attempts yet	1s	1024 MB	Judgeable
FrizuraGiven current and desired strand lengths, find the fewest contiguous cuts (each at one height) that turn the current lengths into the desired ones, or -1 if impossible.	Medium6	Union-findSorting+1	No attempts yet	1s	1024 MB	Judgeable
Suspects and WitnessesGiven witness statements that name innocent guests and a cap K on stealers, count the guests who are innocent in every consistent scenario.	Medium6	GraphBFS	No attempts yet	40s	1024 MB	Judgeable
Tax CollectorsFind the maximum total weight of a simple path with exactly four edges in a weighted tree of up to 200000 vertices.	Medium6	TreeDynamic programming	No attempts yet	9s	1024 MB	Judgeable