Problems

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Total results29,478 problems

Decimal Digit
Easy3
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Knight Tour
Easy3
Simulation, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Missed Call
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Arithmetic Progression
Easy3
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maze Construction
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Hockey
Easy3
Geometry, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Lottery
Easy3
Combinatorics, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Binary to Octal Conversion
Easy3
Bit manipulation, Math+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Messages
Easy3
Simulation, Array+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Six Degrees of Kevin Bacon
Easy3
BFS, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Eumha Railway 998
Easy3
Geometry, Math
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
K-Sejun Numbers
Easy3
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Serial Numbers
Easy3
Sorting, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Repairing Pipe Leaks
Easy3
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Walking
Easy3
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Make It One
Easy3
Dynamic programming, Math
No attempts yet
Time limit
0.15s
Memory limit
128 MB
Judgeable
Date Cycle Calculation
Easy3
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
4 MB
Judgeable
Diet
Easy3
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Guitar Concert
Easy3
Bit manipulation, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maximum Product
Easy3
Math, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Largest Lucky Number
Easy3
Recursion, Brute force+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Count Numbers Made Only of 4 and 7
Easy3
Brute force, Combinatorics+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Transparent Mosaic
Easy3
Array, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Greeting
Easy3
Dynamic programming
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Lost Parentheses
Easy3
Greedy, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cyclic Words
Easy3
String, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Yongsik Goes to Camp
Easy3
Simulation, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Youngsik and Friends' Ball Toss
Easy3
Simulation, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
I Am Pokemon Master Dasom
Easy3
Hash map, Implementation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Common Permutation
Easy3
Hash map, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Modular Exponentiation
Easy3
Math, Number theory+1
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Lucky Ticket
Easy3
Prefix sum, Brute force+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
DNA Decoding
Easy3
Simulation, String+1
No attempts yet
Time limit
5s
Memory limit
16 MB
Judgeable
Seongjun and Chocolate
Easy3
Simulation, Brute force+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Number of Trailing Zeros in a Factorial
Easy3
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Garbage Collection
Easy3
Simulation, Implementation+2
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Hide and Seek
Easy3
BFS, Graph
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Crossword
Easy3
String, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Card Bundle Sorting
Easy3
Heap, Greedy
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Disjoint Set Operations
Easy3
Union-find
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Cipher
Easy3
String, Simulation+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Woodcut Traces
Easy3
Simulation, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Avoiding Food Waste
Easy3
BFS, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Prime Palindrome
Easy3
Math, Brute force+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Number Word Sort
Easy3
Sorting, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Password Generation
Easy3
Backtracking, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Common Names
Easy3
Hash map, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Multiple of Three
Easy3
String, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Firework Show
Easy3
Array, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Extended Fibonacci Numbers
Easy3
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Distinct Numbers
Easy3
Math, Binary search+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Logic Professor
Easy3
Brute force, Math
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Encryption Key
Easy3
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Set Difference
Easy3
Hash map, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Safe Password Check
Easy3
Number theory, Math+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Cipher
Easy3
Simulation, Matrix+2
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Broken Odometer
Easy3
Math, Implementation+1
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Median Filter
Easy3
Matrix, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
01 Tiles
Easy3
Dynamic programming, Math
No attempts yet
Time limit
0.75s
Memory limit
256 MB
Judgeable
Carbon Compounds
Easy3
Brute force, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Repairing a Mud Road
Easy3
Greedy, Intervals
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Maximum Subarray Sum
Easy3
Dynamic programming, Array
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Tower of Hanoi
Easy3
Recursion, Math+1
No attempts yet
Time limit
6s
Memory limit
128 MB
Judgeable
Finding Numbers
Easy3
Binary search, Sorting+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Triangle
Easy3
Geometry, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Painted Areas
Easy3
BFS, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minimum Heap
Easy3
Heap, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Find Prime Numbers
Easy3
Math, Number theory+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Meeting Room Scheduling
Easy3
Greedy, Sorting+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Integer Triangle
Easy3
Dynamic programming, Matrix
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Postfix Expression Evaluation 2
Easy3
Stack, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Jumong's Armor Materials
Easy3
Two pointers, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Snail 2
Easy3
Simulation, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Printer Queue
Easy3
Queue, Simulation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
DNA
Easy3
String, Greedy+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Surprising String
Easy3
String, Brute force+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Travel Plan
Easy3
Union-find, Graph+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Tree Traversal
Easy3
Tree, DFS+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Minesweeper
Easy3
Matrix, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Overtaking
Easy3
Dynamic programming, Array+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Sum of Numbers 2
Easy3
Two pointers, Prefix sum+1
No attempts yet
Time limit
0.5s
Memory limit
128 MB
Judgeable
Counting Consecutive Sums
Easy3
Math, Number theory
No attempts yet
Time limit
2s
Memory limit
32 MB
Judgeable
Rounding
Easy3
Math, Implementation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Text Message
Easy3
Simulation, String+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Completing a Magic Square
Easy3
Math, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
IP Network Address
Easy3
Bit manipulation, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Negative Binary
Easy3
Math, Implementation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Downward Game
Easy3
Dynamic programming, Matrix
No attempts yet
Time limit
1s
Memory limit
4 MB
Judgeable
Pebbles
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Statistics
Easy3
Array, Sorting+1
No attempts yet
Time limit
2s
Memory limit
256 MB
Judgeable
Picture Comparison
Easy3
Brute force, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Card 1
Easy3
Queue, Simulation
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Card 2
Easy3
Queue, Simulation+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Polygon Area
Easy3
Geometry, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
2D Array Range Sum
Easy3
Prefix sum, Matrix+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable
Diagonal Across Tiles
Easy3
Math, Number theory
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Drawing Lines
Easy3
Intervals, Sorting+1
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Maze Search
Easy3
BFS, Graph+1
No attempts yet
Time limit
1s
Memory limit
192 MB
Judgeable
Magic Square Classification
Easy3
Matrix, Implementation+1
No attempts yet
Time limit
1s
Memory limit
128 MB
Judgeable
Pinary Numbers
Easy3
Dynamic programming, Math+1
No attempts yet
Time limit
2s
Memory limit
128 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Decimal DigitSimulate long division of A by B to output the N-th digit after the decimal point.	Easy3	SimulationMath+1	No attempts yet	2s	128 MB	Judgeable
Knight TourCheck whether a given sequence of 36 squares on a 6x6 board forms a valid closed knight's tour with legal moves between consecutive squares and back to the start.	Easy3	SimulationArray+1	No attempts yet	2s	128 MB	Judgeable
Missed CallSimulate an album of N songs with 5-second gaps and a phone ringing every D seconds to find the first ring Kangto can actually hear.	Easy3	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
Arithmetic ProgressionGiven a sequence S and starting value A0, find the smallest common difference d >= 0 of an arithmetic progression so that floor(A0+(i+1)d) equals S_i for every index.	Easy3	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Maze ConstructionSimulate a sequence of forward moves and turns on a grid, then print the smallest rectangular map marking visited cells as passable and the rest as walls.	Easy3	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
HockeyCount how many given points lie inside or on the boundary of a stadium shape formed by a rectangle and two semicircular ends.	Easy3	GeometryImplementation	No attempts yet	2s	128 MB	Judgeable
LotteryGiven N, M, K, compute the probability that two random M-subsets of 1..N share at least K numbers using the hypergeometric distribution.	Easy3	CombinatoricsMath+1	No attempts yet	2s	128 MB	Judgeable
Binary to Octal ConversionConvert a binary number with up to 1,000,000 digits into its octal representation.	Easy3	Bit manipulationMath+2	No attempts yet	1s	128 MB	Judgeable
MessagesGiven sheets of names passed around a circle with P/N marks, find who wrote each hurtful (N) message and about whom.	Easy3	SimulationArray+2	No attempts yet	1s	128 MB	Judgeable
Six Degrees of Kevin BaconGiven an unweighted friendship graph, find the vertex whose sum of shortest distances to all others is minimal, breaking ties by smallest index.	Easy3	BFSGraph+1	No attempts yet	2s	128 MB	Judgeable
Eumha Railway 998Find the point on the train's straight-line path where it comes closest to a given station, guaranteed to have integer coordinates.	Easy3	GeometryMath	No attempts yet	2s	128 MB	Judgeable
K-Sejun NumbersCount integers from 1 to N whose every prime factor is at most K, given N up to 100000 and K up to 100.	Easy3	MathNumber theory+1	No attempts yet	2s	128 MB	Judgeable
Serial NumbersSort serial numbers by length, then digit-sum, then a custom lexicographic rule where digits precede letters.	Easy3	SortingString+1	No attempts yet	2s	128 MB	Judgeable
Repairing Pipe LeaksGiven leak positions and a fixed tape length, compute the minimum number of length-L tapes needed so each leak is covered with at least 0.5 margin on both sides.	Easy3	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
WalkingCompute the minimum time to walk from (0,0) to (X,Y) on a grid where straight moves cost W and diagonal moves cost S.	Easy3	MathGreedy	No attempts yet	2s	128 MB	Judgeable
Make It OneCompute the minimum number of divide-by-3, divide-by-2, or subtract-1 operations needed to reduce N to 1.	Easy3	Dynamic programmingMath	No attempts yet	0.15s	128 MB	Judgeable
Date Cycle CalculationFind the smallest year whose Earth, Sun, and Moon cycle counters, each resetting at fixed limits, match a given triple of values.	Easy3	SimulationMath+1	No attempts yet	2s	4 MB	Judgeable
DietGiven G, find all natural numbers a such that a^2 minus some natural number's square equals G, printing them in increasing order or -1 if none exist.	Easy3	MathNumber theory+1	No attempts yet	2s	128 MB	Judgeable
Guitar ConcertGiven up to 10 guitars each covering a subset of up to 50 songs, find the minimum number of guitars needed to play the maximum possible number of songs.	Easy3	Bit manipulationBrute force+1	No attempts yet	2s	128 MB	Judgeable
Maximum ProductSplit S into K positive integers as equal as possible to maximize their product, given S and K up to 100 and 20.	Easy3	MathGreedy	No attempts yet	2s	128 MB	Judgeable
Largest Lucky NumberGiven N up to 1,000,000, find the largest number no greater than N whose digits are only 4s and 7s.	Easy3	RecursionBrute force+1	No attempts yet	2s	256 MB	Judgeable
Count Numbers Made Only of 4 and 7Count integers between A and B (up to 1e9) whose digits are all 4s and 7s.	Easy3	Brute forceCombinatorics+2	No attempts yet	2s	128 MB	Judgeable
Transparent MosaicGiven N rectangular paper sheets on a 100x100 grid, count cells covered by more than M sheets.	Easy3	ArraySimulation+1	No attempts yet	2s	128 MB	Judgeable
GreetingGiven health costs and joy values for up to 20 people, pick a subset maximizing total joy while keeping total health loss below 100.	Easy3	Dynamic programming	No attempts yet	2s	128 MB	Judgeable
Lost ParenthesesGiven an arithmetic expression with only plus and minus signs, place parentheses to minimize the evaluated result.	Easy3	GreedyString+1	No attempts yet	2s	128 MB	Judgeable
Cyclic WordsCount how many words are distinct once each is allowed to be read starting from any position around a circle.	Easy3	StringBrute force+1	No attempts yet	2s	128 MB	Judgeable
Yongsik Goes to CampFor N bus schedules given by first departure, interval, and count, find the minimum wait until Yongsik can board any bus after arriving at time T, or -1 if none is available.	Easy3	SimulationMath+1	No attempts yet	2s	128 MB	Judgeable
Youngsik and Friends' Ball TossSimulate a ball being passed clockwise or counterclockwise by L seats depending on parity of catch count, counting throws until someone catches it M times.	Easy3	SimulationImplementation+1	No attempts yet	2s	128 MB	Judgeable
I Am Pokemon Master DasomBuild a bidirectional mapping between Pokemon numbers and names, then answer up to 100,000 lookup queries either way.	Easy3	Hash mapImplementation+1	No attempts yet	2s	256 MB	Judgeable
Common PermutationFor each pair of input strings, count letter frequencies and output the multiset intersection sorted alphabetically as the longest common rearranged subsequence.	Easy3	Hash mapString+1	No attempts yet	2s	128 MB	Judgeable
Modular ExponentiationCompute A raised to the power B modulo C efficiently using fast modular exponentiation.	Easy3	MathNumber theory+1	No attempts yet	0.5s	128 MB	Judgeable
Lucky TicketFind the longest even-length substring of a digit string whose first half digit sum equals its second half digit sum.	Easy3	Prefix sumBrute force+2	No attempts yet	2s	128 MB	Judgeable
DNA DecodingRepeatedly merge the last two bases of a DNA string using a fixed lookup table until one base remains, then output it.	Easy3	SimulationString+1	No attempts yet	5s	16 MB	Judgeable
Seongjun and ChocolateGiven chocolate and coffee doses with time-decaying effect radii, sum the positive radii (minimum 1) for each query time.	Easy3	SimulationBrute force+2	No attempts yet	1s	128 MB	Judgeable
Number of Trailing Zeros in a FactorialCount the trailing zeros of N! for N up to 500 by counting factors of 5.	Easy3	MathNumber theory+1	No attempts yet	2s	128 MB	Judgeable
Garbage CollectionSimulate a garbage truck visiting points in order, returning to the dump when its load is full or would overflow, and compute the total distance traveled.	Easy3	SimulationImplementation+2	No attempts yet	1s	128 MB	Judgeable
Hide and SeekCompute the minimum number of moves to reach position K from N on the number line using BFS with steps +1, -1, or doubling.	Easy3	BFSGraph	No attempts yet	2s	128 MB	Judgeable
CrosswordGiven a filled crossword grid, extract every maximal horizontal or vertical run of letters of length at least two and output the lexicographically smallest such word.	Easy3	StringImplementation+1	No attempts yet	2s	128 MB	Judgeable
Card Bundle SortingGiven N sorted card bundle sizes, find the minimum total comparisons to merge them all into one bundle using an optimal merge strategy (classic huffman-like heap problem).	Easy3	HeapGreedy	No attempts yet	2s	128 MB	Judgeable
Disjoint Set OperationsImplement a union-find structure that merges sets and answers whether two elements share a set across a sequence of operations.	Easy3	Union-find	No attempts yet	2s	128 MB	Judgeable
CipherEncrypt a lowercase text by shifting each letter backward in the alphabet by the position value of a repeating key letter, leaving spaces unchanged but still consuming a key character.	Easy3	StringSimulation+1	No attempts yet	2s	256 MB	Judgeable
Woodcut TracesSimulate a tool moving on an N by N grid following U/D/L/R commands, ignoring out-of-bounds moves, and mark each point as unvisited, vertical-only, horizontal-only, or both.	Easy3	SimulationMatrix+1	No attempts yet	2s	128 MB	Judgeable
Avoiding Food WasteGiven a grid marked with food waste cells, find the size of the largest 4-directionally connected component using BFS/DFS or union-find.	Easy3	BFSDFS+1	No attempts yet	2s	128 MB	Judgeable
Prime PalindromeFind the smallest number greater than or equal to N that is both a prime and a palindrome.	Easy3	MathBrute force+1	No attempts yet	2s	256 MB	Judgeable
Number Word SortSort integers from M to N by comparing their digits spelled out as English words rather than by numeric value, then print 10 per line.	Easy3	SortingString+1	No attempts yet	2s	128 MB	Judgeable
Password GenerationGenerate all length-L increasing letter combinations from a given set of C letters that contain at least one vowel and two consonants, printed in lexicographic order.	Easy3	BacktrackingBrute force+1	No attempts yet	2s	128 MB	Judgeable
Common NamesGiven two lists of unique lowercase names, find and print the count and sorted list of names common to both.	Easy3	Hash mapSorting+1	No attempts yet	2s	256 MB	Judgeable
Multiple of ThreeGiven a huge number as a digit string, repeatedly sum its digits until one digit remains, then report how many steps it took and whether the number is divisible by 3.	Easy3	StringMath+1	No attempts yet	2s	128 MB	Judgeable
Firework ShowGiven N firework periods and an end time C, count how many distinct seconds from 1 to C have at least one firework fired by any student.	Easy3	ArrayMath+1	No attempts yet	2s	128 MB	Judgeable
Extended Fibonacci NumbersCompute the sign and absolute value modulo 1e9 of the Fibonacci sequence extended to negative indices for a given n up to 1,000,000 in absolute value.	Easy3	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Sum of Distinct NumbersGiven a sum S, find the largest number of distinct positive integers that can add up to exactly S.	Easy3	MathBinary search+1	No attempts yet	2s	128 MB	Judgeable
Logic ProfessorGiven N statements each claiming exactly x of them are true, find the largest consistent count of true statements or -1 if none works.	Easy3	Brute forceMath	No attempts yet	2s	128 MB	Judgeable
Encryption KeyDetermine for each large number S whether all its prime factors exceed one million, using trial division up to that bound.	Easy3	Number theoryMath+1	No attempts yet	2s	128 MB	Judgeable
Set DifferenceGiven two sets of up to 500,000 natural numbers each, output the count and sorted list of elements present in A but not in B.	Easy3	Hash mapSorting+1	No attempts yet	2s	256 MB	Judgeable
Safe Password CheckGiven a number P equal to the product of two primes and a threshold K, decide if both primes are at least K, otherwise output the smaller prime.	Easy3	Number theoryMath+1	No attempts yet	2s	256 MB	Judgeable
CipherGiven an encrypted string built by zigzag row reading of a column-filled table, reconstruct the original string for a given number of columns.	Easy3	SimulationMatrix+2	No attempts yet	2s	128 MB	Judgeable
Broken OdometerConvert an odometer reading that skips the digit 4 back into the real distance traveled, using a base-9-like digit mapping.	Easy3	MathImplementation+1	No attempts yet	0.5s	128 MB	Judgeable
Median FilterApply a 3x3 median filter over an image and count filtered pixels whose median value is at least a given threshold.	Easy3	MatrixSorting+1	No attempts yet	2s	128 MB	Judgeable
01 TilesCount length-N binary strings tileable by '1' and '00' pieces, modulo 15746, which reduces to a Fibonacci recurrence.	Easy3	Dynamic programmingMath	No attempts yet	0.75s	256 MB	Judgeable
Carbon CompoundsParse three molecules of C,H,O atoms and find coefficients 1 to 10 for each side that balance atom counts, lexicographically smallest.	Easy3	Brute forceString+1	No attempts yet	2s	128 MB	Judgeable
Repairing a Mud RoadGiven non-overlapping puddle intervals and fixed-length planks, find the minimum number of planks needed to cover all puddles.	Easy3	GreedyIntervals	No attempts yet	2s	128 MB	Judgeable
Maximum Subarray SumGiven up to 100,000 integers, compute the maximum sum of a non-empty contiguous subarray.	Easy3	Dynamic programmingArray	No attempts yet	1s	128 MB	Judgeable
Tower of HanoiPrint the minimum move count for Tower of Hanoi with N disks, using big-integer count for N up to 100 and the explicit move sequence when N is at most 20.	Easy3	RecursionMath+1	No attempts yet	6s	128 MB	Judgeable
Finding NumbersGiven N integers and M queries, output for each query whether it exists in the array, requiring an efficient lookup method.	Easy3	Binary searchSorting+1	No attempts yet	1s	128 MB	Judgeable
TriangleGiven three points, classify the triangle they form as degenerate, equilateral, isosceles or scalene, and further by its largest angle type.	Easy3	GeometryImplementation+1	No attempts yet	2s	128 MB	Judgeable
Painted AreasCount connected components of 1-cells in a grid (4-directional adjacency) and output the count and the size of the largest component.	Easy3	BFSDFS+1	No attempts yet	2s	128 MB	Judgeable
Minimum HeapImplement a min-heap to support inserting natural numbers and repeatedly extracting the smallest, printing 0 when empty.	Easy3	HeapImplementation	No attempts yet	1s	128 MB	Judgeable
Find Prime NumbersPrint all prime numbers between two given bounds M and N, one per line, using an efficient sieve up to 1,000,000.	Easy3	MathNumber theory+1	No attempts yet	2s	256 MB	Judgeable
Meeting Room SchedulingGiven N meetings with start and end times, select the maximum number of non-overlapping meetings using a classic greedy interval scheduling approach.	Easy3	GreedySorting+1	No attempts yet	2s	128 MB	Judgeable
Integer TriangleGiven a triangle of up to 500 rows, compute the maximum sum path from top to bottom moving diagonally at each step.	Easy3	Dynamic programmingMatrix	No attempts yet	2s	128 MB	Judgeable
Postfix Expression Evaluation 2Evaluate a postfix expression using given operand values and print the result rounded to two decimal places.	Easy3	StackString+1	No attempts yet	2s	128 MB	Judgeable
Jumong's Armor MaterialsCount how many pairs of given numbers sum to a target value M, using each material at most once per pair.	Easy3	Two pointersArray+1	No attempts yet	2s	128 MB	Judgeable
Snail 2Simulate a snail-like spiral fill on an M by N grid and count how many times the path turns before every cell is visited.	Easy3	SimulationMatrix+1	No attempts yet	2s	128 MB	Judgeable
Printer QueueSimulate a queue where documents are printed only when no higher-priority document remains, and find the print order of a specific document.	Easy3	QueueSimulation	No attempts yet	2s	128 MB	Judgeable
DNAGiven N DNA strings of length M, construct the string minimizing total Hamming distance to all, breaking ties lexicographically, and output that distance.	Easy3	StringGreedy+1	No attempts yet	2s	128 MB	Judgeable
Surprising StringFor each string, check for every gap size whether all pairs of letters at that fixed distance are distinct, and report if the string is 'surprising'.	Easy3	StringBrute force+1	No attempts yet	2s	128 MB	Judgeable
Travel PlanGiven an adjacency matrix of cities, decide if consecutive cities in a given visit order all lie in the same connected component.	Easy3	Union-findGraph+1	No attempts yet	2s	128 MB	Judgeable
Tree TraversalBuild a binary tree from parent-child input and print its preorder, inorder, and postorder traversals.	Easy3	TreeDFS+1	No attempts yet	2s	128 MB	Judgeable
MinesweeperGiven an N x N minesweeper grid with mine counts (possibly multi-mine cells), output each empty cell's summed adjacent mine count, capping at 'M' for 10+.	Easy3	MatrixSimulation+1	No attempts yet	2s	128 MB	Judgeable
OvertakingGiven entry and exit orders of N cars, count how many cars are not part of the longest common subsequence, meaning they overtook someone.	Easy3	Dynamic programmingArray+1	No attempts yet	2s	128 MB	Judgeable
Sum of Numbers 2Given N positive integers and a target M, count contiguous subarrays whose sum equals M.	Easy3	Two pointersPrefix sum+1	No attempts yet	0.5s	128 MB	Judgeable
Counting Consecutive SumsCount the number of ways to express a given natural number N as a sum of one or more consecutive natural numbers.	Easy3	MathNumber theory	No attempts yet	2s	32 MB	Judgeable
RoundingGiven an integer up to 99,999,999, repeatedly round its digits at increasing place values (tens, hundreds, etc.) using standard rounding rules and print the final result.	Easy3	MathImplementation+1	No attempts yet	2s	128 MB	Judgeable
Text MessageSimulate typing a message on a numeric keypad, summing key press costs and extra wait times when consecutive characters share a key (except spaces).	Easy3	SimulationString+1	No attempts yet	2s	128 MB	Judgeable
Completing a Magic SquareGiven a 3x3 magic square with up to three cells erased (marked 0), fill in the missing positive integers so all rows, columns, and diagonals share the same sum.	Easy3	MathMatrix+1	No attempts yet	2s	128 MB	Judgeable
IP Network AddressGiven a list of IPv4 addresses, compute the smallest common network address and its mask that covers them all using bitwise operations.	Easy3	Bit manipulationImplementation	No attempts yet	2s	128 MB	Judgeable
Negative BinaryConvert a given decimal integer into its base -2 (negabinary) representation.	Easy3	MathImplementation	No attempts yet	2s	128 MB	Judgeable
Downward GameGiven an N x 3 grid with limited column transitions between rows, compute the maximum and minimum total path sums from top to bottom.	Easy3	Dynamic programmingMatrix	No attempts yet	1s	4 MB	Judgeable
PebblesGiven N pebbles to place on grid points, compute the minimum possible perimeter of the smallest bounding rectangle covering all of them.	Easy3	MathImplementation	No attempts yet	1s	128 MB	Judgeable
StatisticsGiven N odd integers, compute and print the rounded mean, median, mode (second smallest if tied), and range.	Easy3	ArraySorting+1	No attempts yet	2s	256 MB	Judgeable
Picture ComparisonGiven N small 5x7 grids, find the pair of pictures with the fewest differing cells and output their indices.	Easy3	Brute forceMatrix+1	No attempts yet	2s	128 MB	Judgeable
Card 1Simulate a queue where you discard the front card then rotate the next card to the back, printing the discard order and final survivor.	Easy3	QueueSimulation	No attempts yet	2s	128 MB	Judgeable
Card 2Simulate the Josephus-style card elimination process to find which card number remains last for a given N.	Easy3	QueueSimulation+1	No attempts yet	2s	128 MB	Judgeable
Polygon AreaGiven the ordered vertices of a simple polygon, compute its area using the shoelace formula, rounded to one decimal place.	Easy3	GeometryMath+1	No attempts yet	2s	128 MB	Judgeable
2D Array Range SumBuild a 2D prefix sum over an N by M grid and answer up to 10,000 rectangle sum queries in O(1) each.	Easy3	Prefix sumMatrix+1	No attempts yet	2s	128 MB	Judgeable
Diagonal Across TilesGiven a grid of x by y unit tiles, count how many tiles a diagonal from corner to corner passes through using the gcd formula.	Easy3	MathNumber theory	No attempts yet	1s	128 MB	Judgeable
Drawing LinesGiven N line segments on a number line, compute the total length covered by at least one segment, merging overlaps.	Easy3	IntervalsSorting+1	No attempts yet	1s	192 MB	Judgeable
Maze SearchFind the minimum number of cells traversed on a grid path from top-left to bottom-right using BFS shortest path.	Easy3	BFSGraph+1	No attempts yet	1s	192 MB	Judgeable
Magic Square ClassificationRead multiple square matrices and classify each into one of five magic square categories based on row, column, diagonal sums, distinctness, and consecutiveness.	Easy3	MatrixImplementation+1	No attempts yet	1s	128 MB	Judgeable
Pinary NumbersCount binary strings of length N that start with 1 and have no two consecutive 1s, using Fibonacci-style counting with big integers up to N=90.	Easy3	Dynamic programmingMath+1	No attempts yet	2s	128 MB	Judgeable