Interview core

Mediums from real onsites

Under construction

Still being built. Things may change

Total results3,612 problems

Credit Card Recovery
Medium5
Brute force, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Moocast
Medium5
Graph, Union-find+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Cities and States
Medium5
Hash map, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Banknotes and Roulette
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Graph Search 2
Medium5
BFS, Graph
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Emoticons
Medium5
BFS, Graph+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Ruthless Boss
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Score of a Subsequence
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Jump Jump 2
Medium5
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Connecting Edges 2
Medium5
Graph, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Phone Number Riddle (Small)
Medium5
String, Hash map+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Phone Number Riddle (Large)
Medium5
String, Hash map+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Paper Pieces
Medium5
Brute force, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Convenience Store 2
Medium5
Math, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sprinklers
Medium5
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Finding Prefixes
Medium5
Trie, String
No attempts yet
Time limit
1s
Memory limit
1536 MB
Judgeable
Integer Sequence
Medium5
Math, Dynamic programming+2
No attempts yet
Time limit
0.25s
Memory limit
512 MB
Judgeable
Cow Dance Show
Medium5
Binary search, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Why Did the Cow Cross the Road 6
Medium5
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Bulbs
Medium5
Greedy, Implementation
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flight Plan
Medium5
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Junoh Lives for Lunch!!
Medium5
Binary search, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
What Is Dynamic Programming?
Medium5
Dynamic programming, Matrix+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Tetromino
Medium5
Brute force, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Resignation
Medium5
Dynamic programming, Brute force+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Laboratory
Medium5
Brute force, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Connectivity Potential
Medium5
Graph, Shortest path+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Line Friends (Small)
Medium5
Graph, BFS+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Image Quilting (Small)
Medium5
Dynamic programming, Implementation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Flower Path
Medium5
Brute force, Backtracking+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Scallion Chicken
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Archers of the Geumgang Range
Medium5
Stack, Array+2
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Red Ginseng Game (Easy)
Medium5
BFS, Graph+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Reincarnated as a Slime Researcher (Easy)
Medium5
Greedy, Number theory+2
No attempts yet
Time limit
0.5s
Memory limit
512 MB
Judgeable
Rainwater
Medium5
Array, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Pony Express (Small)
Medium5
Dynamic programming, Shortest path+1
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Core Training (All Cores)
Medium5
Greedy, Math+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Rectangles and Queries
Medium5
Prefix sum, Matrix+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hamming distance queries
Medium5
Prefix sum, String+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Two water jugs
Medium5
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Slurpy
Medium5
Recursion, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Project Scheduling
Medium5
Topological sort, Dynamic programming+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Shoemaker's Job Order
Medium5
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Building a ranch
Medium5
Dynamic programming, Matrix+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Stone Skipping (SUJEBI)
Medium5
Math, Brute force+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Flea Market
Medium5
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Escaping the Barracks
Medium5
Binary search, BFS+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Deranging Hat
Medium5
Simulation, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Education
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
5s
Memory limit
512 MB
Judgeable
Delayed Work
Medium5
Math, Brute force+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Purple Rain
Medium5
Array, Greedy+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Front Nine
Medium5
Probability, Dynamic programming+2
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Candy Sales
Medium5
Array, Prefix sum+1
No attempts yet
Time limit
6s
Memory limit
512 MB
Judgeable
Exciting Startup
Medium5
Binary search, Math+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
3D Printed Statues
Medium5
Greedy, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Seat Assignment Algorithm
Medium5
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Easy Quest
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
3s
Memory limit
512 MB
Judgeable
Robot Energy Source Order
Medium5
Sorting, Greedy+2
No attempts yet
Time limit
0.2s
Memory limit
128 MB
Judgeable
Cakey McCakeFace
Medium5
Hash map, Array+2
No attempts yet
Time limit
7s
Memory limit
512 MB
Judgeable
Birthday Cake
Medium5
Geometry, Bit manipulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Imperfect GPS
Medium5
Geometry, Simulation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Sugoroku
Medium5
Dynamic programming, BFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Hangul LCS
Medium5
Dynamic programming, String+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Consultations before resignation
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Probability that the knight stays on the board
Medium5
Dynamic programming, Probability+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Pascal's triangle
Medium5
Array, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Calling Extraterrestrial Intelligence Again
Medium5
Number theory, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
The Stove
Medium5
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Art Exhibition
Medium5
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Maximum range sum? 1
Medium5
Array, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Cute Ryan
Medium5
Two pointers, Sliding window+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Signal 1
Medium5
Dynamic programming, Sorting+2
No attempts yet
Time limit
1.5s
Memory limit
128 MB
Judgeable
Largest average
Medium5
Greedy, Math+2
No attempts yet
Time limit
1s
Memory limit
64 MB
Judgeable
The Lawyer
Medium5
Sorting, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Africa
Medium5
Implementation, Greedy
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Roasting Emma is a barista too
Medium5
Tree, DFS+2
No attempts yet
Time limit
1.5s
Memory limit
128 MB
Judgeable
Gears (2)
Medium5
Simulation, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
CCTV Blind Spots
Medium5
Brute force, Backtracking+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Cowburger set discount
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rest Stops
Medium5
Greedy, Sorting+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Milking Order
Medium5
Topological sort, Greedy+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Family Tree
Medium5
Graph, DFS+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
QueryreuQ
Medium5
String, Dynamic programming+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Zigzag Sequence
Medium5
Array, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Counting the closest pair sums
Medium5
Sorting, Two pointers+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Miss That Bus and You Are Late!!
Medium5
Simulation, Queue+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Warring States
Medium5
Union-find, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balloon Factory
Medium5
Binary search, Greedy+2
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Drain Pipes
Medium5
Dynamic programming, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ah-Choo!
Medium5
Dynamic programming, Array+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Martian DNA
Medium5
Sliding window, Array+2
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Card merge game
Medium5
Greedy, Heap+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Gahui the Grappler!!
Medium5
Geometry, Math+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
Dolls
Medium5
Brute force, Prefix sum+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Rotating Sushi
Medium5
Sliding window, Two pointers+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Longest Consecutive Subsequence
Medium5
Dynamic programming, Hash map+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Meditation Disturber
Medium5
Prefix sum, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable
1, 2, 3 Sum 5
Medium5
Dynamic programming, Math+2
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
1, 2, 3 Addition 7
Medium5
Dynamic programming, Combinatorics+2
No attempts yet
Time limit
0.25s
Memory limit
512 MB
Judgeable
Missing Gnomes
Medium5
Greedy, Implementation+2
No attempts yet
Time limit
2s
Memory limit
512 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Credit Card RecoveryGiven a 16-digit encrypted string, find all original card numbers that the given encrypt rule (bump min up, max down, swap) would produce, printed in ascending order or banana.	Medium5	Brute forceImplementation+2	No attempts yet	1s	128 MB	Judgeable
MoocastGiven N cow coordinates, find the smallest integer X such that the graph connecting pairs whose squared distance is at most X is connected.	Medium5	GraphUnion-find+2	No attempts yet	2s	512 MB	Judgeable
Cities and StatesGiven up to 200,000 cities with names and two-letter state codes, count unordered pairs whose first two name letters match the other city's state code and vice versa, with different states.	Medium5	Hash mapString+2	No attempts yet	2s	512 MB	Judgeable
Banknotes and RouletteSplit banknotes so the two equal-sum groups leave the smallest leftover, then add half of twice that leftover to each person's total.	Medium5	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Graph Search 2After each of q planned roads is built, print each city's shortest-path distance to city 1, where it takes one edge.	Medium5	BFSGraph	No attempts yet	2s	512 MB	Judgeable
EmoticonsStarting from one emoticon on screen with an empty clipboard, find the minimum seconds to reach exactly S using copy, paste, and delete-one operations.	Medium5	BFSGraph+2	No attempts yet	2s	512 MB	Judgeable
The Ruthless BossGiven n distinct deadlines, find the largest integer k so that scheduling all jobs, each taking exactly k hours back to back, meets every deadline.	Medium5	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Score of a SubsequenceFind the maximum over all contiguous subarrays of the weighted sum where the k-th element from the subarray start contributes k times its value.	Medium5	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Jump Jump 2Given a walk that adds or subtracts A_i at each step, count the stones reachable from start s, excluding s unless a cycle returns to it.	Medium5	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
Connecting Edges 2Given a weighted edge list, pick the order of adding edges that makes the total weight added up to the moment s and t first become connected as small as possible.	Medium5	GraphSorting+2	No attempts yet	2s	512 MB	Judgeable
Phone Number Riddle (Small)Given a shuffled string formed from the English words of a phone number's digits, recover the digits, which are guaranteed to be in ascending order.	Medium5	StringHash map+2	No attempts yet	5s	512 MB	Judgeable
Phone Number Riddle (Large)A shuffled concatenation of the English words for a phone number's digits is given; recover the digits, which are in ascending order.	Medium5	StringHash map+2	No attempts yet	5s	512 MB	Judgeable
Paper PiecesCut an N x M digit grid into horizontal or vertical strips and maximize the sum of the numbers those strips form.	Medium5	Brute forceBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Convenience Store 2Given n customer points, place one store anywhere to minimize the total Manhattan distance to all customers and print that minimum sum.	Medium5	MathSorting+2	No attempts yet	2s	512 MB	Judgeable
SprinklersPlace two fixed sprinklers and choose radii so every flower is covered, minimizing the sum of squared radii; print that minimum as an integer.	Medium5	SortingGreedy+2	No attempts yet	2s	512 MB	Judgeable
Finding PrefixesGiven a set of N strings, count how many of M query strings appear as a prefix of at least one string in the set.	Medium5	TrieString	No attempts yet	1s	1536 MB	Judgeable
Integer SequenceGiven x, y, the last two digits of A0 and A1, and a large index n, print the last two digits of An where An = xAn-1 + yAn-2.	Medium5	MathDynamic programming+2	No attempts yet	0.25s	512 MB	Judgeable
Cow Dance ShowFind the smallest stage size K so that the total show time, where the next cow starts as soon as a dancer leaves, stays within T_max.	Medium5	Binary searchSimulation+2	No attempts yet	2s	512 MB	Judgeable
Why Did the Cow Cross the Road 6Given an N x N grid of pastures, some adjacent pairs blocked by roads, and K cows on distinct cells, count the pairs of cows that cannot reach each other without crossing a road.	Medium5	GraphBFS+2	No attempts yet	2s	512 MB	Judgeable
BulbsFind the fewest laser shots needed so every bulb is on, where each shot also toggles bulbs below it and to its left.	Medium5	GreedyImplementation	No attempts yet	2s	512 MB	Judgeable
Flight PlanFor each pair of latitude/longitude points on a sphere, compute the great-circle distance and the distance of the two-leg path that keeps latitude then longitude constant.	Medium5	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
Junoh Lives for Lunch!!Given each friend's starting position and running speed, decide whether all N friends can meet at one point within time T.	Medium5	Binary searchSorting+2	No attempts yet	2s	512 MB	Judgeable
What Is Dynamic Programming?Count paths from the top-left cell to the bottom-right cell of an n by m grid when each step moves right, down, or diagonally down-right, printed modulo 1e9+7.	Medium5	Dynamic programmingMatrix+1	No attempts yet	2s	512 MB	Judgeable
TetrominoGiven an N x M grid of positive integers, place one of the 5 tetrominoes (with rotations and reflections) to maximize the sum of covered cells.	Medium5	Brute forceImplementation+2	No attempts yet	2s	512 MB	Judgeable
ResignationGiven each day's consultation length and payment, pick a non-overlapping set of jobs that all finish before day N+1 to maximize total payment.	Medium5	Dynamic programmingBrute force+1	No attempts yet	2s	512 MB	Judgeable
LaboratoryPlace exactly 3 walls on empty cells of a small grid to maximize the number of cells the virus cannot reach.	Medium5	Brute forceBFS+2	No attempts yet	2s	512 MB	Judgeable
Connectivity PotentialGiven a directed graph as an adjacency matrix, compute the number of hops in the longest shortest path times the number of ordered pairs attaining it.	Medium5	GraphShortest path+2	No attempts yet	2s	512 MB	Judgeable
Line Friends (Small)Given N line segments, build a graph where segments are adjacent when they overlap, then answer shortest-path queries between pairs of segments.	Medium5	GraphBFS+2	No attempts yet	2s	256 MB	Judgeable
Image Quilting (Small)Given two H by W grayscale images, choose one pixel per row forming a connected seam (rows shift by at most one column) minimizing the sum of squared pixel differences, and output that minimum.	Medium5	Dynamic programmingImplementation	No attempts yet	1s	512 MB	Judgeable
Flower PathPlace three plus-shaped flowers of 5 cells each on an N x N grid so no two overlap, all stay inside, and the total rented-cell cost is minimal.	Medium5	Brute forceBacktracking+2	No attempts yet	2s	256 MB	Judgeable
Scallion ChickenFind the largest integer piece length x such that the scallions yield at least C pieces, then print the total leftover length.	Medium5	Binary searchGreedy+2	No attempts yet	2s	256 MB	Judgeable
Archers of the Geumgang RangeEach archer's dragon moves right and eats peaks lower than its start until it meets a taller peak; find the largest count any archer can eat.	Medium5	StackArray+2	No attempts yet	2s	256 MB	Judgeable
Red Ginseng Game (Easy)Two tokens move around a cycle, each jumping exactly D seats left or right per turn; find the fewest moves until a token lands on the other token's holder.	Medium5	BFSGraph+2	No attempts yet	1s	512 MB	Judgeable
Reincarnated as a Slime Researcher (Easy)Given a starting integer K, repeatedly factor it into two factors at least 2, minimizing the maximum number of splits along any root to leaf path.	Medium5	GreedyNumber theory+2	No attempts yet	0.5s	512 MB	Judgeable
RainwaterGiven stack heights across a 2D world, compute the total rainwater trapped between the blocks after heavy rain.	Medium5	ArrayTwo pointers+2	No attempts yet	1s	256 MB	Judgeable
Pony Express (Small)Cities lie on a line with a horse in each; find the minimum time from city 1 to city N, switching horses at intermediate cities, subject to each horse's endurance limit.	Medium5	Dynamic programmingShortest path+1	No attempts yet	5s	512 MB	Judgeable
Core Training (All Cores)With K = N, the AI works only if every core succeeds; split U training units among cores to maximize the product of final success probabilities.	Medium5	GreedyMath+2	No attempts yet	5s	512 MB	Judgeable
Rectangles and QueriesGiven an N by N matrix with values at most 10, answer many rectangle queries, each asking how many distinct integers appear inside the submatrix.	Medium5	Prefix sumMatrix+2	No attempts yet	2s	512 MB	Judgeable
Hamming distance queriesGiven binary strings a and b, answer queries asking for the Hamming distance between a substring of a and a substring of b.	Medium5	Prefix sumString+2	No attempts yet	6s	512 MB	Judgeable
Two water jugsGiven two jug capacities a and b, decide whether some sequence of fills, empties, and pours can leave exactly c liters in one jug.	Medium5	MathNumber theory+1	No attempts yet	2s	512 MB	Judgeable
SlurpyDecide whether each uppercase string is a Slurpy, meaning a Slimp immediately followed by a Slump, where both are defined by recursive grammar rules.	Medium5	RecursionString+2	No attempts yet	2s	512 MB	Judgeable
Project SchedulingGiven each task's duration and its prerequisite tasks, find the minimum total time to finish the whole project.	Medium5	Topological sortDynamic programming+2	No attempts yet	2s	512 MB	Judgeable
Shoemaker's Job OrderOrder N jobs to minimize the total fine paid while each job waits, using the shortest processing time per fine ratio first, with lexicographically smallest ties.	Medium5	GreedySorting	No attempts yet	2s	512 MB	Judgeable
Building a ranchGiven an M by N grid with trees and rocks as obstacles, find the side length of the largest square subgrid that contains no obstacle.	Medium5	Dynamic programmingMatrix+2	No attempts yet	1s	512 MB	Judgeable
Stone Skipping (SUJEBI)For each step size d, sum the cells at multiples of d and pick the d with the largest sum, printing 0 0 if that sum is not positive.	Medium5	MathBrute force+2	No attempts yet	2s	512 MB	Judgeable
Flea MarketEach person has a supply or demand of fleas at unit-distance positions; find the minimum total delivery cost.	Medium5	GreedyPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
Escaping the BarracksFind the minimum level needed to walk from (0,0) to (n-1,m-1) on an n by m grid, using at most one jump that skips over exactly one block in a straight line.	Medium5	Binary searchBFS+2	No attempts yet	1s	256 MB	Judgeable
Deranging HatGiven a string, find a sorting network that turns its sorted letters back into the original string, following a specified rule.	Medium5	SimulationSorting+2	No attempts yet	2s	512 MB	Judgeable
EducationAssign departments to buildings by a deterministic greedy rule after sorting students descending, matching each to the cheapest available building that fits.	Medium5	GreedySorting+2	No attempts yet	5s	512 MB	Judgeable
Delayed WorkChoose the integer number of painters that minimizes total cost X times painters plus K/P times P delay charge, then round to three decimals.	Medium5	MathBrute force+2	No attempts yet	1s	512 MB	Judgeable
Purple RainGiven a string of R and B characters, find the contiguous block maximizing \|r - b\|, breaking ties by westernmost start then westernmost end.	Medium5	ArrayGreedy+2	No attempts yet	1s	512 MB	Judgeable
Front NineGiven a clamped random walk on [0,h] with step probabilities, compute the expected area under the piecewise-linear terrain over n steps.	Medium5	ProbabilityDynamic programming+2	No attempts yet	6s	512 MB	Judgeable
Candy SalesFor each day j, print the minimum over all i at most j of w_i + (j - i).	Medium5	ArrayPrefix sum+1	No attempts yet	6s	512 MB	Judgeable
Exciting StartupFind the smallest number of pieces b so that a string of length t split into b ordered pieces, each carrying a suffix "_a/b", fits in n-character messages.	Medium5	Binary searchMath+2	No attempts yet	3s	512 MB	Judgeable
3D Printed StatuesWith one printer that prints a statue or a new printer each day, find the fewest days to produce at least n statues.	Medium5	GreedyMath+2	No attempts yet	2s	512 MB	Judgeable
Seat Assignment AlgorithmAssign n new passengers to seats in a 3-3-3 airplane layout by repeatedly applying an empty-seat and exit-row priority rule, then print the final layout.	Medium5	SimulationImplementation+1	No attempts yet	1s	512 MB	Judgeable
Easy QuestGiven a sequence of gifts (+type), costs (-type), and unicorns (0), decide if every cost can be paid and choose the lexicographically smallest item type for each unicorn.	Medium5	GreedyImplementation+2	No attempts yet	3s	512 MB	Judgeable
Robot Energy Source OrderReorder n energy sources, each with acceleration a_i and duration s_i, to maximize total distance, and print the gain over the given order.	Medium5	SortingGreedy+2	No attempts yet	0.2s	128 MB	Judgeable
Cakey McCakeFaceGiven sorted entry and exit timestamps, find the smallest nonnegative time difference d that maximizes how many entry times t satisfy t + d is an exit time.	Medium5	Hash mapArray+2	No attempts yet	7s	512 MB	Judgeable
Birthday CakeGiven up to 50 candle points and up to 15 cuts, decide whether the cuts carve the cake so that every resulting piece holds exactly one candle.	Medium5	GeometryBit manipulation+2	No attempts yet	2s	512 MB	Judgeable
Imperfect GPSGiven a running path and a recording interval t, compute the percentage of the real distance the GPS receiver loses by sampling positions at fixed times and joining them with straight lines.	Medium5	GeometrySimulation+2	No attempts yet	2s	512 MB	Judgeable
SugorokuSquares 2 to N+1 are each marked 0 or 1; find the smallest die size j such that some sequence of rolls from 1 to j reaches or passes square N+2 without landing on any square marked 1.	Medium5	Dynamic programmingBFS+2	No attempts yet	2s	512 MB	Judgeable
Hangul LCSGiven two Hangul strings of up to 1000 characters each, compute the length of their longest common subsequence in characters.	Medium5	Dynamic programmingString+2	No attempts yet	2s	512 MB	Judgeable
Consultations before resignationGiven up to 1.5 million days, each with a job of length T_i and pay P_i, pick jobs that fit before day N+1 to maximize total pay.	Medium5	Dynamic programmingArray+2	No attempts yet	2s	512 MB	Judgeable
Probability that the knight stays on the boardA knight on an N by N board makes K random moves, each of the eight directions equally likely; find the probability it is still on the board after K moves.	Medium5	Dynamic programmingProbability+2	No attempts yet	2s	512 MB	Judgeable
Pascal's triangleBuild Pascal's triangle and sum all entries inside the equilateral sub-triangle whose top cell is row R, position C, with side length W.	Medium5	ArrayDynamic programming+2	No attempts yet	1s	512 MB	Judgeable
Calling Extraterrestrial Intelligence AgainFor each query with m and fraction a/b, find primes p and q with pq <= m and a/b <= p/q <= 1 that maximize the product pq.	Medium5	Number theoryMath+2	No attempts yet	2s	512 MB	Judgeable
The StoveEach visitor stays for one time unit at a distinct arrival time; with at most K lights, minimize total stove-on time by skipping the largest idle gaps.	Medium5	GreedySorting+1	No attempts yet	1s	256 MB	Judgeable
Art ExhibitionChoose a subset of artworks maximizing the sum of values minus the difference between the largest and smallest sizes in the subset.	Medium5	SortingPrefix sum+1	No attempts yet	1s	256 MB	Judgeable
Maximum range sum? 1Maintain an array under point updates. For each range query, find the maximum of U times a subarray sum plus V times its length over all subarrays inside the range.	Medium5	ArrayBrute force+2	No attempts yet	1s	128 MB	Judgeable
Cute RyanGiven a row of N dolls labeled 1 or 2, find the length of the shortest contiguous block containing at least K dolls labeled 1.	Medium5	Two pointersSliding window+2	No attempts yet	1s	256 MB	Judgeable
Signal 1Choose a subset of points with distinct x-coordinates; maximize the total Euclidean length of the polyline joining them in increasing x order.	Medium5	Dynamic programmingSorting+2	No attempts yet	1.5s	128 MB	Judgeable
Largest averageGiven N grades, repeatedly replace any two numbers with their average until one remains; find the largest possible final value.	Medium5	GreedyMath+2	No attempts yet	1s	64 MB	Judgeable
The LawyerFor each day, decide whether two of that day's meetings are disjoint and, if so, output the pair with the smallest earlier-meeting index, then smallest later index.	Medium5	SortingGreedy+2	No attempts yet	2s	512 MB	Judgeable
AfricaGiven N African countries in visit order, find the minimum total visa fee in dollars, counting Namibia's cheaper Cape Town visa when South Africa comes first.	Medium5	ImplementationGreedy	No attempts yet	1s	256 MB	Judgeable
Roasting Emma is a barista tooGiven a weighted tree, compute for every vertex the sum of shortest distances to all other vertices.	Medium5	TreeDFS+2	No attempts yet	1.5s	128 MB	Judgeable
Gears (2)Simulate K turns on a row of 8-tooth gears where a turning gear rotates its neighbor only if the touching teeth have opposite poles, then count gears whose top tooth is S.	Medium5	SimulationImplementation+2	No attempts yet	2s	512 MB	Judgeable
CCTV Blind SpotsPlace each of up to 8 cameras in one of its allowed rotations on an 8x8 grid so that the fewest cells stay unwatched, given walls block sight.	Medium5	Brute forceBacktracking+2	No attempts yet	1s	512 MB	Judgeable
Cowburger set discountGiven prices for burgers, sides, and drinks, report the undiscounted total and the minimum total after forming disjoint triples where each item in a set is sold at 10% off.	Medium5	GreedySorting+2	No attempts yet	1s	128 MB	Judgeable
Rest StopsBessie rests at grass stops along a trail and must never fall behind Farmer John; maximize total tastiness of eaten grass.	Medium5	GreedySorting+2	No attempts yet	2s	512 MB	Judgeable
Milking OrderGiven a partial order between some cows and fixed positions for others, find the earliest position cow 1 can occupy.	Medium5	Topological sortGreedy+2	No attempts yet	2s	512 MB	Judgeable
Family TreeGiven a set of mother-child pairs, classify the relationship between two cows as siblings, direct ancestor, aunt, cousins, or unrelated, following a fixed rule order.	Medium5	GraphDFS+2	No attempts yet	2s	512 MB	Judgeable
QueryreuQMaintain a string under append and pop-back operations, and after each operation print the number of palindromic substrings it contains.	Medium5	StringDynamic programming+2	No attempts yet	1s	1024 MB	Judgeable
Zigzag SequenceGiven a sequence, find the longest contiguous block in which no three consecutive terms are monotone increasing or monotone decreasing.	Medium5	ArrayTwo pointers+2	No attempts yet	1s	1024 MB	Judgeable
Counting the closest pair sumsGiven n integers and a target v, count how many index pairs have a sum whose distance from v is as small as possible.	Medium5	SortingTwo pointers+2	No attempts yet	2s	512 MB	Judgeable
Miss That Bus and You Are Late!!Simulate a single-lane bus stop where each bus parks in the frontmost free spot, waits if a bus ahead is still parked, and departs after its dwell time; report the parking spot of the m-th bus.	Medium5	SimulationQueue+1	No attempts yet	1s	512 MB	Judgeable
Warring StatesProcess alliance and war records between groups, merging by sum for alliances and subtracting troops for wars, then report surviving groups sorted by troop count.	Medium5	Union-findImplementation+2	No attempts yet	1s	128 MB	Judgeable
Balloon FactoryFind the minimum time for N workers, each producing one balloon every A_i minutes, to finish M balloons in parallel.	Medium5	Binary searchGreedy+2	No attempts yet	1s	256 MB	Judgeable
Drain PipesCount the number of ways to pick quantities of each pipe type, within the given stock, so the chosen pipes sum to exactly x.	Medium5	Dynamic programmingArray+2	No attempts yet	1s	128 MB	Judgeable
Ah-Choo!Compute the least Dynamic Time Warping distance between two equal-length integer sequences, where every point must match at least one point of the other and matches cannot cross.	Medium5	Dynamic programmingArray+1	No attempts yet	1s	512 MB	Judgeable
Martian DNAGiven a string over K symbols and minimum counts for R of them, find the length of the shortest contiguous substring meeting all the quotas, or report impossible.	Medium5	Sliding windowArray+2	No attempts yet	2s	1024 MB	Judgeable
Card merge gameEach merge replaces two chosen cards with their sum; after exactly m merges, minimize the total sum of all cards.	Medium5	GreedyHeap+2	No attempts yet	1s	512 MB	Judgeable
Gahui the Grappler!!Given a piecewise linear function through points (i, y_i) with y_0=0, decide whether the ray y=kx meets it anywhere besides the origin.	Medium5	GeometryMath+2	No attempts yet	2s	512 MB	Judgeable
DollsGiven N numbers in a fixed order, find a contiguous segment of at least K numbers whose standard deviation is minimized, and output that standard deviation.	Medium5	Brute forcePrefix sum+2	No attempts yet	1s	512 MB	Judgeable
Rotating SushiOn a circular belt of N sushi plates, find the maximum number of distinct kinds in any k consecutive plates, counting the coupon kind c once more if it is not already present.	Medium5	Sliding windowTwo pointers+2	No attempts yet	1s	512 MB	Judgeable
Longest Consecutive SubsequenceGiven an integer sequence, find the longest subsequence whose values form an arithmetic run with common difference 1, keeping the original order.	Medium5	Dynamic programmingHash map+1	No attempts yet	2s	256 MB	Judgeable
Meditation DisturberEach bird on the left or right chirps on some seconds; remove one bird so the peak absolute value of the running signed sum over M seconds is minimized, and report its index and that value.	Medium5	Prefix sumImplementation+2	No attempts yet	2s	512 MB	Judgeable
1, 2, 3 Sum 5Count the ordered sums of 1, 2, and 3 that add to n, with no equal value adjacent, modulo 1,000,000,009.	Medium5	Dynamic programmingMath+2	No attempts yet	1s	512 MB	Judgeable
1, 2, 3 Addition 7Count ordered compositions of n into exactly m parts, where each part is 1, 2, or 3, modulo 1,000,000,009.	Medium5	Dynamic programmingCombinatorics+2	No attempts yet	0.25s	512 MB	Judgeable
Missing GnomesGiven a subsequence of 1..n, find the lexicographically smallest permutation of 1..n that contains it as a subsequence.	Medium5	GreedyImplementation+2	No attempts yet	2s	512 MB	Judgeable