Problems

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Total results29,466 problems

Towers
Medium4
Stack, Array
No attempts yet
Time limit
1.5s
Memory limit
128 MB
Judgeable
Bracket Value
Medium4
Stack, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Budget Allocation
Medium4
Binary search, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Eating Pancakes
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Security Guard
Medium4
Math, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Colored Paper Perimeter
Medium4
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Climbing Stairs
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Finding Regions
Medium4
BFS, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fire Engines
Medium4
Greedy, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Treasure Island
Medium4
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Number Cards
Medium4
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Amusement Park
Medium4
Intervals, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Marble Game
Medium4
Dynamic programming, Game theory+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Meeting Preparation
Medium4
Graph, BFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Omok
Medium4
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Music Program
Medium4
Topological sort, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Changing a Bill with Coins
Medium4
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Balance Scale
Medium4
Dynamic programming, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Toy Assembly
Medium4
Graph, DFS+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Drawing Polygons
Medium4
String matching, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stacking Colored Paper
Medium4
Dynamic programming, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Clock Card Rank
Medium4
Brute force, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Selecting Numbers
Medium4
Graph, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Area of the Union of Four Rectangles
Medium4
Geometry, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Product of a Contiguous Subsequence
Medium4
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Maximum Number of Noncrossing Circle Chords
Medium4
Dynamic programming, Intervals+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Decoding EDSAC Data
Medium4
Bit manipulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Fax
Medium4
Simulation, String+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Nondecreasing Numbers
Medium4
Combinatorics, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Next Greater Number
Medium4
String, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Interior Points of a Convex Lattice Polygon
Medium4
Geometry, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Polycube Surface Area
Medium4
Simulation, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kyuhyun's Secret Text Message
Medium4
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chip Stack Shuffle
Medium4
Simulation, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number of Points Visible from the Origin
Medium4
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Brainf*ck Interpreter
Medium4
Stack, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Stacking Drums
Medium4
Geometry, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sum of Consecutive Natural Numbers
Medium4
Math, Number theory
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Lotto
Medium4
Dynamic programming, Combinatorics+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pancake Flipping
Medium4
Greedy, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Candy Sharing Game
Medium4
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number Play
Medium4
Greedy, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Surveyor Jiyoon
Medium4
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Horizontal and Vertical Puzzle
Medium4
Brute force, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Chains
Medium4
Greedy, Sorting+1
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Tree Cutting
Medium4
Binary search, Greedy
No attempts yet
Time limit
1s
Memory limit
256 MB
Judgeable
Make the Largest Number
Medium4
Stack, Greedy
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
ALPS-Style Voting
Medium4
Simulation, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
When Homework Feels Impossible
Medium4
Simulation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Apple Catching Game
Medium4
Dynamic programming, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Planet X3
Medium4
Bit manipulation, Math+1
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Box Sorting
Medium4
Array, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Basketball Lead Time
Medium4
Simulation, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Dormitory Floor
Medium4
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
A Library at Home
Medium4
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Graphics Quiz
Medium4
Array, Sliding window+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
4 and 7
Medium4
Math, Bit manipulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Seat War
Medium4
Array, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kayaks and the Strong Wind
Medium4
Greedy, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Frequency Sort
Medium4
Hash map, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Solve Sudoku by Cross-Hatching
Medium4
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Infinite Binary Tree Traversal
Medium4
Math, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Three Kangaroos
Medium4
Math, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Same Remainder Divisors
Medium4
Number theory, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Apple Trees
Medium4
Geometry, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Next Greater Number with the Same Digits
Medium4
Greedy, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Peg Move Count
Medium4
Simulation, Matrix+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Choosing a Name
Medium4
Array, Greedy+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Campfire
Medium4
Simulation, Hash map+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Firefly
Medium4
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Ants
Medium4
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Greedy Pigs
Medium4
Simulation, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Bridging Signals
Medium4
Binary search, Dynamic programming+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Galaxy Meeting
Medium4
Shortest path, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Battle Order Score
Medium4
Array, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Good Friends
Medium4
Sliding window, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Immigration Inspection
Medium4
Binary search, Math
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Candy Game
Medium4
Simulation, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Rabbit Movement
Medium4
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Inequality
Medium4
Math, Brute force+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Woncheol's Rebellion
Medium4
Simulation, Geometry+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Teams with Sum Zero
Medium4
Array, Two pointers+1
No attempts yet
Time limit
4s
Memory limit
128 MB
Judgeable
Remaining Letters in a Word Search
Medium4
Matrix, String matching+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Election Winners
Medium4
Simulation, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Sheep
Medium4
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Quiz Hints
Medium4
String, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Urinal Flush Schedule
Medium4
Simulation, String+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Kkung the Shepherd
Medium4
BFS, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Snake
Medium4
Simulation, Queue+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Magic Square
Medium4
Matrix, Math+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Race Ranking
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Programming Language Z
Medium4
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Breaking Couples
Medium4
Graph, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Download
Medium4
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
MO
Medium4
Simulation, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Who Wins Gold, Silver, and Bronze?
Medium4
Simulation, Array+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Card Pickup Game
Medium4
Queue, Simulation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Spies
Medium4
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
String Expansion and Distance
Medium4
Dynamic programming, String
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Molecular Mass
Medium4
Stack, Recursion+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
TowersFor each tower in a line, find the nearest tower to its left with height at least as large, using a monotonic stack approach.	Medium4	StackArray	No attempts yet	1.5s	128 MB	Judgeable
Bracket ValueParse a bracket string with two bracket types and compute its defined nested value, or output 0 if it is invalid.	Medium4	StackString+1	No attempts yet	1s	128 MB	Judgeable
Budget AllocationGiven budget requests and a total cap, find the maximum integer cap value such that capping requests at that value keeps the total within budget.	Medium4	Binary searchGreedy	No attempts yet	1s	128 MB	Judgeable
Eating PancakesGiven a box A×B×C and D unit-thickness slices removed one dimension at a time, maximize the remaining volume by choosing which dimension to shrink each cut.	Medium4	GreedyMath+1	No attempts yet	1s	128 MB	Judgeable
Security GuardConvert each point's side-based coordinates to a position along the rectangle's perimeter and sum the minimal clockwise/counterclockwise distances from a fixed point to every store.	Medium4	MathImplementation+1	No attempts yet	1s	128 MB	Judgeable
Colored Paper PerimeterGiven up to 100 axis-aligned 10x10 black squares on a 100x100 grid, compute the total perimeter of their union.	Medium4	MatrixSimulation+1	No attempts yet	1s	128 MB	Judgeable
Climbing StairsFind the maximum score reachable by climbing stairs one or two at a time without stepping on three consecutive stairs, ending on the last stair.	Medium4	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Finding RegionsGiven a grid with several rectangles marked as blocked, find the number of connected empty regions and output their areas sorted ascending.	Medium4	BFSArray+1	No attempts yet	1s	128 MB	Judgeable
Fire EnginesGiven sorted positions of pumps and fire engines on a line, assign each engine a distinct pump to minimize total distance connected.	Medium4	GreedyDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Treasure IslandGiven a grid of land and water cells, find the largest shortest-path distance between two connected land cells (grid diameter via multi-source BFS).	Medium4	BFSGraph+1	No attempts yet	1s	512 MB	Judgeable
Number CardsCount the ways to split a digit string into tokens each representing a valid card number from 1 to 34 (no leading zero issues implied).	Medium4	Dynamic programmingString	No attempts yet	1s	128 MB	Judgeable
Amusement ParkGiven ride schedules with 10-minute buffers before and after each, find the longest free interval within 10:00-22:00 where no ride's blocked window overlaps.	Medium4	IntervalsSorting+1	No attempts yet	1s	128 MB	Judgeable
Marble GameCompute Grundy-style win/lose states for a two-pile subtraction game with three fixed move sizes and report the winner for five given starting positions.	Medium4	Dynamic programmingGame theory+1	No attempts yet	1s	128 MB	Judgeable
Meeting PreparationFind connected components in a graph and for each pick the vertex minimizing the eccentricity (graph center).	Medium4	GraphBFS+1	No attempts yet	1s	128 MB	Judgeable
OmokGiven a 19x19 Omok board, detect whether black or white has an exact five-in-a-row (not six or more) and output the winning color and the starting coordinate of that line.	Medium4	MatrixSimulation+1	No attempts yet	1s	128 MB	Judgeable
Music ProgramMerge several partial orderings of singers into one total order using topological sort, or report impossibility if a cycle exists.	Medium4	Topological sortGraph+1	No attempts yet	1s	128 MB	Judgeable
Changing a Bill with CoinsCount the number of ways to make an exact target sum T using bounded quantities of k coin denominations.	Medium4	Dynamic programming	No attempts yet	1s	128 MB	Judgeable
Balance ScaleGiven a set of weights, determine for each marble weight whether it can be balanced using weights placed on either pan (subset sums with +/- coefficients).	Medium4	Dynamic programmingBrute force+1	No attempts yet	1s	128 MB	Judgeable
Toy AssemblyCompute how many units of each basic part are needed to build one finished toy given a DAG of assembly quantities.	Medium4	GraphDFS+1	No attempts yet	1s	128 MB	Judgeable
Drawing PolygonsGiven a reference closed-path digit sequence tracing a polygon, find which candidate sequences represent the same polygon allowing rotation of starting point and direction reversal but not geometric rotation or reflection.	Medium4	String matchingString+1	No attempts yet	1s	128 MB	Judgeable
Stacking Colored PaperGiven N rectangles with allowed 90-degree rotation, find the longest chain where each sheet fits entirely inside the previous one.	Medium4	Dynamic programmingSorting+1	No attempts yet	1s	128 MB	Judgeable
Clock Card RankGiven four clockwise digits on a card, compute the minimal rotation (clock number) and find its rank among all distinct clock numbers from digits 1-9.	Medium4	Brute forceSimulation+1	No attempts yet	1s	128 MB	Judgeable
Selecting NumbersGiven a functional graph i->A_i on 1..N, find the maximum set of indices closed under this mapping (union of cycles) and print it.	Medium4	GraphArray+1	No attempts yet	1s	128 MB	Judgeable
Area of the Union of Four RectanglesGiven four axis-aligned rectangles, compute the total area covered by their union.	Medium4	GeometryImplementation	No attempts yet	1s	128 MB	Judgeable
Maximum Product of a Contiguous SubsequenceGiven N decimal numbers between 0.0 and 9.9, find the contiguous subsequence with the maximum product and print it rounded to three decimals.	Medium4	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
Maximum Number of Noncrossing Circle ChordsGiven up to 50 chords on 100 circle points with distinct endpoints, find the maximum subset of chords with no two crossing.	Medium4	Dynamic programmingIntervals+1	No attempts yet	1s	128 MB	Judgeable
Decoding EDSAC DataDecode an EDSAC instruction (character opcode, address, word/double-word flag) into the fixed-point two's-complement decimal number its 17-bit binary pattern represents.	Medium4	Bit manipulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
FaxImplement run-length encoding with specific bit-packed run and literal prefix formats, splitting long runs and literal blocks according to size limits.	Medium4	SimulationString+2	No attempts yet	1s	128 MB	Judgeable
Nondecreasing NumbersCount the number of n-digit strings (digits 0-9, leading zeros allowed) that are nondecreasing, for n up to 64 requiring big integers.	Medium4	CombinatoricsMath	No attempts yet	1s	128 MB	Judgeable
Next Greater NumberGiven a large number as a digit string, find the smallest permutation of its digits that is greater than it, or report BIGGEST if none exists.	Medium4	StringGreedy+1	No attempts yet	1s	128 MB	Judgeable
Interior Points of a Convex Lattice PolygonGiven a convex lattice polygon, for every integer y-line find and report the leftmost and rightmost interior lattice points.	Medium4	GeometryImplementation+1	No attempts yet	1s	128 MB	Judgeable
Polycube Surface AreaValidate that unit cubes placed in a given order always connect by a face to a prior cube starting at the origin, then output the polycube's surface area or the index of the first invalid cube.	Medium4	SimulationHash map+1	No attempts yet	1s	128 MB	Judgeable
Kyuhyun's Secret Text MessageConvert each character to a 5-bit code, fill an R by C matrix in clockwise spiral order with the concatenated bits (padding with zeros), then print the matrix read row by row.	Medium4	MatrixSimulation+1	No attempts yet	1s	128 MB	Judgeable
Chip Stack ShuffleSimulate repeated riffle shuffles of two chip stacks and find the minimum number of shuffles to reach a target stack, or report -1.	Medium4	SimulationString	No attempts yet	1s	128 MB	Judgeable
Number of Points Visible from the OriginCount lattice points (x,y) with 0<=x,y<=N visible from the origin, meaning gcd(x,y)=1 or one coordinate is 0/1 edge case.	Medium4	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Brainf*ck InterpreterImplement a Brainfsck interpreter that parses a program per test case, checks bracket matching, and executes it printing output or a compile error.	Medium4	StackSimulation+1	No attempts yet	1s	128 MB	Judgeable
Stacking DrumsGiven bottom-row circle centers of drums stacked pyramid-style each resting on two below, compute the final top drum's center coordinates.	Medium4	GeometrySimulation+1	No attempts yet	1s	128 MB	Judgeable
Sum of Consecutive Natural NumbersFor numbers up to 2^31, count the ways each can be expressed as a sum of two or more consecutive positive integers.	Medium4	MathNumber theory	No attempts yet	1s	128 MB	Judgeable
LottoCount n-element increasing subsequences from 1..m where each next number is at least double the previous, using combinatorics or DP.	Medium4	Dynamic programmingCombinatorics+1	No attempts yet	1s	128 MB	Judgeable
Pancake FlippingSort a stack of N distinct pancakes into increasing order from top using prefix reversals, within a bound of 2N-3 flips.	Medium4	GreedySimulation+1	No attempts yet	1s	128 MB	Judgeable
Candy Sharing GameSimulate a circle of students repeatedly halving and passing candies right, rounding odd counts up, until all counts equalize, then report the round count and final value.	Medium4	SimulationArray	No attempts yet	1s	128 MB	Judgeable
Number PlayFor each N, greedily factor it into digits 9 down to 2 to find the minimum digit count of a number whose digits multiply to N, or report -1 if impossible.	Medium4	GreedyMath+1	No attempts yet	1s	128 MB	Judgeable
Surveyor JiyoonGiven three lines in ax+by+c=0 form, compute the area of the triangle they form, or 0 if they do not form one.	Medium4	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Horizontal and Vertical PuzzleGiven 6 three-letter words, choose 3 as rows and 3 as columns so the grid's columns also match the remaining words, outputting the lexicographically smallest valid arrangement.	Medium4	Brute forceString+1	No attempts yet	1s	128 MB	Judgeable
ChainsGiven lengths of N chains, find the minimum number of links to open and close so that all chains merge into a single chain.	Medium4	GreedySorting+1	No attempts yet	1s	256 MB	Judgeable
Tree CuttingBinary search for the maximum saw height H so that trimming all trees above H yields at least M meters of wood total.	Medium4	Binary searchGreedy	No attempts yet	1s	256 MB	Judgeable
Make the Largest NumberGiven an N-digit number, remove exactly K digits while keeping relative order to form the largest possible remaining number.	Medium4	StackGreedy	No attempts yet	1s	128 MB	Judgeable
ALPS-Style VotingSimulate a D'Hondt-style seat allocation: filter staff by a 5% vote threshold, generate divided scores, pick the top 14, and count chips per staff sorted by name.	Medium4	SimulationSorting+1	No attempts yet	1s	128 MB	Judgeable
When Homework Feels ImpossibleSimulate a die rolling boustrophedon-style across an R by C grid and sum the top face values recorded at each visited cell.	Medium4	SimulationMath+1	No attempts yet	1s	128 MB	Judgeable
Apple Catching GameMove a fixed-size basket left or right along N cells to catch a sequence of falling apples with minimum total movement distance.	Medium4	Dynamic programmingGreedy+1	No attempts yet	1s	128 MB	Judgeable
Planet X3Given up to a million numbers, compute the sum over all pairs of the XOR of their values by counting set bits per bit position.	Medium4	Bit manipulationMath+1	No attempts yet	1s	192 MB	Judgeable
Box SortingSort an array into increasing order using the minimum number of cyclic-rotation commands, following a specified cycle-decomposition construction.	Medium4	ArraySimulation+1	No attempts yet	1s	128 MB	Judgeable
Basketball Lead TimeGiven timestamped scoring events over a 48 minute game, compute the total time each team held the lead.	Medium4	SimulationSorting+1	No attempts yet	1s	128 MB	Judgeable
Dormitory FloorGiven counts of border tiles and interior tiles of a rectangle grid, find the rectangle's two integer side lengths.	Medium4	MathBrute force+1	No attempts yet	1s	128 MB	Judgeable
A Library at HomeFind the minimum number of top-moves needed so a pile of numbered books ends up sorted 1..N from top to bottom.	Medium4	GreedyArray	No attempts yet	1s	128 MB	Judgeable
Graphics QuizFor each of 5 grades, find the longest contiguous run of desks where at least one student has that grade, then output the best length and the smallest grade achieving it.	Medium4	ArraySliding window+1	No attempts yet	1s	128 MB	Judgeable
4 and 7Given K, output the K-th smallest positive integer whose digits are only 4 or 7, using a binary-representation-like construction.	Medium4	MathBit manipulation+1	No attempts yet	1s	128 MB	Judgeable
Seat WarGiven a grid of people and seats, count seats where two or more people are tied at the minimum distance to that seat.	Medium4	ArrayBrute force+1	No attempts yet	1s	128 MB	Judgeable
Kayaks and the Strong WindGiven broken and spare-carrying teams in a line, assign each spare kayak to an adjacent broken team to minimize the number of teams left unable to start.	Medium4	GreedyBrute force+1	No attempts yet	1s	128 MB	Judgeable
Frequency SortSort a sequence of up to 1000 integers by descending frequency, breaking ties by the value's first appearance order in the input.	Medium4	Hash mapSorting+1	No attempts yet	1s	128 MB	Judgeable
Solve Sudoku by Cross-HatchingSimulate repeated Sudoku cross-hatching (single-candidate-per-box scan) on a given grid, filling cells until no more moves apply, and detect rule violations or contradictions.	Medium4	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
Infinite Binary Tree TraversalGiven a string of L/R/P/* moves in an infinite binary tree, sum the node values over all traversals from expanding each '*' into L, R, or P.	Medium4	MathString+1	No attempts yet	1s	128 MB	Judgeable
Three KangaroosGiven three sorted integer positions, compute the maximum number of jumps where an outer point can move to any free integer strictly between the other two.	Medium4	MathGreedy+1	No attempts yet	1s	128 MB	Judgeable
Same Remainder DivisorsGiven N distinct integers, find all M greater than 1 for which all numbers share the same remainder mod M, output divisors of pairwise differences in increasing order.	Medium4	Number theoryMath+1	No attempts yet	1s	128 MB	Judgeable
Apple TreesCompute a triangle's area using the shoelace formula and count how many given points lie inside or on its boundary.	Medium4	GeometryMath+1	No attempts yet	1s	128 MB	Judgeable
Next Greater Number with the Same DigitsGiven an integer, find the smallest number larger than it using exactly the same multiset of digits, or print 0 if impossible.	Medium4	GreedyArray+1	No attempts yet	1s	128 MB	Judgeable
Peg Move CountGiven a 7-line cross-shaped peg board, count how many single peg-jump moves are currently legal.	Medium4	SimulationMatrix+1	No attempts yet	1s	128 MB	Judgeable
Choosing a NameGiven even integers and a range [A,B], find an odd integer in that range maximizing the minimum distance to all given even values.	Medium4	ArrayGreedy+1	No attempts yet	1s	128 MB	Judgeable
CampfireSimulate campfire nights where Sunyoung's presence introduces a new song and other nights merge attendees' known songs, then output everyone who ends up knowing all songs.	Medium4	SimulationHash map+1	No attempts yet	1s	128 MB	Judgeable
FireflyGiven alternating stalagmite and stalactite lengths in a cave, find the flight height destroying the fewest obstacles and how many heights tie for that minimum.	Medium4	Prefix sumArray	No attempts yet	1s	128 MB	Judgeable
AntsSimulate two colliding groups of ants swapping adjacent opposite-direction ants each second and output the arrangement after T seconds.	Medium4	SimulationArray	No attempts yet	1s	128 MB	Judgeable
Greedy PigsSimulate a circular 6-pig feeding process where each pig's next demand is the sum of 4 previous values, and find the first day the total demand exceeds the fixed daily feed supply N.	Medium4	SimulationMath	No attempts yet	1s	128 MB	Judgeable
Bridging SignalsGiven a permutation of wire connections between two ports, find the longest increasing subsequence to maximize non-crossing signals.	Medium4	Binary searchDynamic programming+1	No attempts yet	1s	128 MB	Judgeable
Galaxy MeetingGiven weighted graphs and multiple starting galaxies, find the meeting galaxy that minimizes the sum of squared shortest distances from all participants.	Medium4	Shortest pathGraph+1	No attempts yet	1s	128 MB	Judgeable
Battle Order ScoreCount pairs of items whose relative order matches between a reference sequence and a given permutation, and print as a fraction over N(N-1)/2.	Medium4	ArrayBrute force+1	No attempts yet	1s	128 MB	Judgeable
Good FriendsCount pairs of students within rank distance K whose names have equal length, given names in rank order.	Medium4	Sliding windowArray+1	No attempts yet	1s	128 MB	Judgeable
Immigration InspectionGiven N counters with per-person processing times and M travelers, find the minimum time to process everyone using binary search on the answer.	Medium4	Binary searchMath	No attempts yet	1s	128 MB	Judgeable
Candy GameGiven a colored N×N grid, determine the longest same-color run achievable in any row or column after performing exactly one swap of two adjacent different-colored cells.	Medium4	SimulationBrute force+1	No attempts yet	1s	128 MB	Judgeable
Rabbit MovementSimulate a rabbit walking on an N×N zigzag-diagonal numbered grid following given moves and sum all visited cell values.	Medium4	MatrixSimulation+1	No attempts yet	1s	128 MB	Judgeable
InequalityCount integer triples X, Y, Z with fixed denominators B, C, D that keep a chain of four strict fraction inequalities between two given bounds true.	Medium4	MathBrute force+1	No attempts yet	1s	128 MB	Judgeable
Woncheol's RebellionSimulate a grid walker's rotations and moves, then find the minimum distance to a target by optionally changing one command to another direction.	Medium4	SimulationGeometry+1	No attempts yet	1s	128 MB	Judgeable
Teams with Sum ZeroCount the number of index triples among N students whose skill values sum to exactly zero.	Medium4	ArrayTwo pointers+1	No attempts yet	4s	128 MB	Judgeable
Remaining Letters in a Word SearchGiven a letter grid and a word list, find every 8-direction occurrence of each word, cross out those letters, and print the remaining letters in row-major order.	Medium4	MatrixString matching+2	No attempts yet	1s	128 MB	Judgeable
Election WinnersGiven M ranked ballots over N candidates, compute pairwise head-to-head wins to find the candidate(s) with the highest number of defeated opponents.	Medium4	SimulationMath+1	No attempts yet	1s	128 MB	Judgeable
SheepUse flood fill to split a grid into fenced regions, then for each region compare sheep and wolf counts to decide survivors, ignoring regions touching the border.	Medium4	BFSGraph+1	No attempts yet	1s	128 MB	Judgeable
Quiz HintsGenerate three progressive hint strings for a text answer by masking letters with dots and revealing them in stages based on rounded fractional counts.	Medium4	StringSimulation+1	No attempts yet	1s	128 MB	Judgeable
Urinal Flush ScheduleSimulate a sensor log to detect when a urinal usage streak of K seconds is followed by an absence streak of L seconds, printing each flush time or NIKAD.	Medium4	SimulationString+1	No attempts yet	1s	128 MB	Judgeable
Kkung the ShepherdUsing grid flood-fill to find fenced regions, determine for each region whether sheep or wolves survive by comparing counts, then output totals.	Medium4	BFSArray+1	No attempts yet	1s	128 MB	Judgeable
SnakeSimulate a classic snake moving on an N x N grid with given apple positions and scheduled turn events, and output the second when it hits a wall or itself.	Medium4	SimulationQueue+1	No attempts yet	1s	128 MB	Judgeable
Magic SquareGiven a 3x3 magic square with up to three erased entries (marked 0), reconstruct the missing values so rows, columns, and diagonals share the same sum.	Medium4	MatrixMath+1	No attempts yet	1s	128 MB	Judgeable
Race RankingSimulate M checkpoint messages in order, keep only valid sequential checkpoint passes per driver, and print final ranking by progress and recency.	Medium4	SimulationImplementation+1	No attempts yet	1s	128 MB	Judgeable
Programming Language ZParse and simulate a tiny toy language with variable assignments, nested REPEAT loops, and PRINT statements, applying mod-10000 arithmetic.	Medium4	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
Breaking CouplesOrient every edge of an undirected graph so each vertex's in-degree and out-degree differ by at most 1, which is always possible via an Euler-tour style pairing on connected components.	Medium4	GraphDFS+1	No attempts yet	2s	128 MB	Judgeable
DownloadGiven download times and playback durations of sequential song pieces, compute the earliest start time so playback never stalls waiting for a piece.	Medium4	GreedyPrefix sum+1	No attempts yet	1s	128 MB	Judgeable
MOSimulate an alternating stone-placing game on a 1D board where placing a stone can capture an enclosed run of opponent stones, then count remaining stones of each color.	Medium4	SimulationArray+1	No attempts yet	1s	128 MB	Judgeable
Who Wins Gold, Silver, and Bronze?Given each athlete's live rank as they finish two sequential races, reconstruct final standings from the second race and output the top three athlete numbers.	Medium4	SimulationArray+1	No attempts yet	1s	128 MB	Judgeable
Card Pickup GameSimulate removing cards 1..N in order from a circular scan of a row, counting how many times the search wraps past the right end.	Medium4	QueueSimulation+1	No attempts yet	1s	128 MB	Judgeable
SpiesSimulate a walk on a grid and report which given spy coordinates ever fall within Chebyshev distance 1 of the walker's path.	Medium4	SimulationArray	No attempts yet	1s	128 MB	Judgeable
String Expansion and DistanceCompute the minimum alignment cost between two strings using edit-distance style dynamic programming with character mismatch costs and a fixed gap penalty K.	Medium4	Dynamic programmingString	No attempts yet	1s	128 MB	Judgeable
Molecular MassParse a nested chemical formula with parentheses and repeat counts, then compute the total molecular mass from atomic weights.	Medium4	StackRecursion+1	No attempts yet	1s	128 MB	Judgeable