Problems

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Total results29,469 problems

Pink Bean Raid
Easy3
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Good Luck
Easy3
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Double Up
Easy3
Math, Hash map
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Very Hard Problem
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
LED Matrix
Easy3
Implementation, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Phoenix
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hanbit Media (Easy)
Easy3
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Apartment
Easy3
Sorting, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Grade Conversion
Easy3
String, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Best Chance
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Increase and Decrease
Easy3
Prefix sum, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Periodic Function (Easy)
Easy3
Prefix sum, Math
No attempts yet
Time limit
0.5s
Memory limit
1024 MB
Judgeable
Work-Study Student
Easy3
Hash map, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Alphabets and Queries (Easy)
Easy3
String, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Folding a String
Easy3
String, Brute force
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Convenience Zone
Easy3
BFS, Matrix
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Working Hard
Easy3
Heap, Simulation
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Senior, Please Buy Me Dinner!
Easy3
Sorting, Hash map+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Geunsu score
Easy3
Math, String
No attempts yet
Time limit
1s
Memory limit
512 MB
Judgeable
Couple Ring Match
Easy3
Hash map, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
APC2shake!
Easy3
Sorting, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Logpresso Maestro
Easy3
Brute force, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Deadly School Route
Easy3
Graph, BFS
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Double
Easy3
Greedy, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pleasant Meeting
Easy3
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Merging Sequences
Easy3
Implementation, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Talking About Numbers
Easy3
String, Math+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Haiku Formatting
Easy3
String, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
If You Sleep Now, You Dream
Easy3
Sorting, Greedy+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Misdelivered letters
Easy3
Array, Brute force
No attempts yet
Time limit
60s
Memory limit
1024 MB
Judgeable
Overtaking
Easy3
Simulation, Array
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Treasure Hunt
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Changes in Club Membership
Easy3
Array, Sliding window
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Simple Editor
Easy3
Stack, Simulation+1
No attempts yet
Time limit
8s
Memory limit
1024 MB
Judgeable
Not PlayStation
Easy3
String, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Card Game (Easy)
Easy3
Greedy, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hyeongwon and the Curious Sequence
Easy3
Simulation, Hash map
No attempts yet
Time limit
0.1s
Memory limit
1024 MB
Judgeable
Stacking Cups
Easy3
Dynamic programming
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dangling Else
Easy3
Recursion, Implementation
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Dream, Passion, Sharing
Easy3
Greedy, Sorting
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Questions Keep Coming
Easy3
Array, Prefix sum
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Events are coming (Easy)
Easy3
Dynamic programming, Simulation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Abo and KINTEX
Easy3
String, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Light ray polygon
Easy3
Math, Geometry
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Bingo Blocking
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pyramids
Easy3
Prefix sum, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Binary Sorting (Easy)
Easy3
Bit manipulation, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Difference between x and x+1
Easy3
Number theory, Math
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Injured Shoulder
Easy3
String, Hash map
No attempts yet
Time limit
5s
Memory limit
1024 MB
Judgeable
Hotel Rooms
Easy3
Segment tree, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Troublesome Keys
Easy3
Simulation, String+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Efficient Inspection
Easy3
Tree, DFS
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Drop the Bit
Easy3
Math, Greedy
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Artifact Excavation
Easy3
Array, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Honggik University
Easy3
String, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Space Archery
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Double Palindrome
Easy3
String, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Heavy-Light Composition
Easy3
String, Hash map
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rook
Easy3
Implementation, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Toy Lock
Easy3
Math, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
\frac{1}{2}(MatKor+ALPS)=AlKor
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Guess the Algorithms That Will Appear at KCPC
Easy3
Hash map, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Synchronizing Bulb Periods
Easy3
Number theory, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Enigma of the Jewelry Case
Easy3
Matrix, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Kingdom's Development Plan
Easy3
Topological sort, Graph+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Alien Attack 2
Easy3
Graph, Union-find+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Bookshelf Bottleneck
Easy3
Implementation, Greedy
No attempts yet
Time limit
3s
Memory limit
1024 MB
Judgeable
Musical Mending
Easy3
Sorting, Math+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Light Up
Easy3
Matrix, Simulation+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Raehwan's Mission to Get a Girlfriend
Easy3
Prefix sum, Two pointers
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Rehwan's Big Taxi Plan
Easy3
Greedy, Sorting
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Hierarchy
Easy3
Graph, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Dialling Digits
Easy3
Hash map, String
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Human Pyramid
Easy3
Math, Binary search
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Knitting Pattern
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Flag Bearer
Easy3
Implementation, String
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Flag Rotation
Easy3
Hash map, Array
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Road to SPC
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Cascade Centrality
Easy3
Tree, DFS+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Connectedness
Easy3
Union-find, Graph
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Garage Door Code
Easy3
Brute force, String matching+1
No attempts yet
Time limit
4s
Memory limit
1024 MB
Judgeable
Lego Lover's Triangle
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Pascal Multiple
Easy3
Dynamic programming, Math
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Split into Odd or Split into Even!
Easy3
Math, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Counting Cross Shapes in a Grid
Easy3
Matrix, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Numbers
Easy3
Sorting, Array+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Differences
Easy3
Sorting, Prefix sum+1
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Solving Sõnasnäkk
Easy3
String, Hash map
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Is it a sequence?
Easy3
Array, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Sequence, Again
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Big Integers
Easy3
String, Implementation
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
A Stack of Gold
Easy3
Math, Implementation
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Welcome Sign
Easy3
String, Implementation+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Office Building
Easy3
Brute force, Matrix+1
No attempts yet
Time limit
1s
Memory limit
2048 MB
Judgeable
Nobody Like That
Easy3
Simulation, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Restore the permutation
Easy3
Matrix, Sorting+1
No attempts yet
Time limit
2s
Memory limit
1024 MB
Judgeable
Piano
Easy3
Greedy, Array
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Paradox
Easy3
Simulation, Implementation
No attempts yet
Time limit
1s
Memory limit
1024 MB
Judgeable
Ordinal Number
Easy3
Recursion, String+1
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable
Faulty Traffic Light
Easy3
Brute force, Implementation
No attempts yet
Time limit
2s
Memory limit
2048 MB
Judgeable

Title	Level	Topics	Solved	Time limit	Memory limit	Judge
Pink Bean RaidGiven three mascots' skill intervals and damage values and Pink Bean's HP, find the second when cumulative damage first brings the HP to 0 or below.	Easy3	SimulationImplementation	No attempts yet	1s	1024 MB	Judgeable
Good LuckGiven A stems and B leaves, where each stem needs 3 or 4 leaves, find the fewest stems and leaves to add so that nothing is left over.	Easy3	MathGreedy	No attempts yet	1s	1024 MB	Judgeable
Double UpEach number can only be doubled into values that share its odd part, so the task is to find the largest group of numbers with the same odd part.	Easy3	MathHash map	No attempts yet	2s	1024 MB	Judgeable
Very Hard ProblemGiven N and M, find the remainder when N! is divided by M, where N can be as large as 10^18 and M as large as 10^7.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
LED MatrixDecide whether every lit pattern LED can be shown on a working matrix LED as the pattern scrolls across the matrix.	Easy3	ImplementationString	No attempts yet	1s	1024 MB	Judgeable
PhoenixGiven X and M, find the sum of magical power of all phoenixes alive after M commands, where each split keeps the total power unchanged.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Hanbit Media (Easy)Given N book prices, split the books into the fewest pages so that no page holds two prices that differ by a factor of two or more.	Easy3	GreedySorting	No attempts yet	1s	1024 MB	Judgeable
ApartmentGiven N and M participants with two hand heights each, find which participant drinks after the lowest hand is moved to the top N times.	Easy3	SortingSimulation	No attempts yet	1s	1024 MB	Judgeable
Grade ConversionGiven Eunseong's old-system grades for N semesters, convert each one to the new B, D, P, or E grade using the previous semester's grade where the rule requires it.	Easy3	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
Best ChanceGiven each item's profit and price, print each item's net profit, which equals its profit minus the largest profit among all other items.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Increase and DecreaseCount the increase-then-decrease numbers in each inclusive range [a, b] for up to 100000 queries, with a and b at most 10^6.	Easy3	Prefix sumImplementation	No attempts yet	1s	1024 MB	Judgeable
Periodic Function (Easy)Given the integral of a periodic function over each unit interval in one period, compute the integral over an arbitrary interval [a, b].	Easy3	Prefix sumMath	No attempts yet	0.5s	1024 MB	Judgeable
Work-Study StudentFor each sentence, output the meanings of dictionary words that start at each position, using the dictionary-smallest word on ties, or -1 if nothing matches.	Easy3	Hash mapString+1	No attempts yet	1s	1024 MB	Judgeable
Alphabets and Queries (Easy)Given a string, answer queries that count maximal runs of one repeated letter inside a range, or shift every letter in a range to the next letter.	Easy3	StringSimulation	No attempts yet	1s	1024 MB	Judgeable
Folding a StringGiven a substring of S, find the maximum number of equal character pairs that touch after folding the strip once between two adjacent characters.	Easy3	StringBrute force	No attempts yet	1s	1024 MB	Judgeable
Convenience ZoneGiven rooms and convenience stores on an N by M grid, find the minimum of (Manhattan distance to the nearest store) times monthly rent over all rooms.	Easy3	BFSMatrix	No attempts yet	2s	1024 MB	Judgeable
Working HardRepeatedly take the most important task, lower its score by M until it is K or lower, and print the day count and each day's satisfaction.	Easy3	HeapSimulation	No attempts yet	1s	512 MB	Judgeable
Senior, Please Buy Me Dinner!Given each senior's promised week, day, and dinner cost plus their money, find the longest run of consecutive days with a promise the senior can afford to pay.	Easy3	SortingHash map+1	No attempts yet	1s	1024 MB	Judgeable
Geunsu scoreGiven a digit string, sum the score of every substring of consecutive 2s, where each substring of length k adds k points.	Easy3	MathString	No attempts yet	1s	512 MB	Judgeable
Couple Ring MatchFind every ring feature worn by exactly two people and print those pairs of names, ignoring anyone whose feature is '-'.	Easy3	Hash mapImplementation	No attempts yet	1s	1024 MB	Judgeable
APC2shake!Pick up to 10 enrolled participants with no ICPC award and no past shake! top-3 finish, ranked by 2024 APC placement, and list their names sorted.	Easy3	SortingImplementation	No attempts yet	2s	1024 MB	Judgeable
Logpresso MaestroGiven timestamped file transfers and the infected computers, find the first computer whose spread through the transfers in time order infects exactly those computers.	Easy3	Brute forceSimulation+1	No attempts yet	1s	1024 MB	Judgeable
Deadly School RouteGiven a grid of red and gray blocks, the task checks whether a path of same-colored blocks with Manhattan jumps up to X connects the top-left and bottom-right corners.	Easy3	GraphBFS	No attempts yet	1s	1024 MB	Judgeable
DoubleGiven a sequence of positive integers, find the fewest doublings of single elements needed to make the sequence non-decreasing.	Easy3	GreedyMath	No attempts yet	1s	1024 MB	Judgeable
Pleasant MeetingFor each time slot from 0.5 to T-0.5, count the friend pairs who are both attending the meeting at that time.	Easy3	Prefix sumArray	No attempts yet	1s	1024 MB	Judgeable
Merging SequencesGiven N sequences, output their total length, the sum of distinct values shared by sequences A and B, and the final result of pairwise merging by larger values.	Easy3	ImplementationSimulation+1	No attempts yet	1s	1024 MB	Judgeable
Talking About NumbersGiven non-negative integers up to 999,999,999, print each one in English words, following the rules for hyphens, commas, and "and".	Easy3	StringMath+1	No attempts yet	1s	1024 MB	Judgeable
Haiku FormattingGiven a line of text, count the syllables in each word by the stated rules and check whether the words can be split into lines of 5, 7, and 5 syllables.	Easy3	StringSimulation	No attempts yet	1s	1024 MB	Judgeable
If You Sleep Now, You DreamGiven N task deadlines, choose a sleep reduction X so that each task takes A-X time after sleeping BX, and find the most tasks that can finish by their deadlines.	Easy3	SortingGreedy+1	No attempts yet	2s	1024 MB	Judgeable
Misdelivered lettersDan must find one house that received its own bill by asking residents which bill they got, using as few visits as possible.	Easy3	ArrayBrute force	No attempts yet	60s	1024 MB	Judgeable
OvertakingGiven each runner's distance per minute, count how many times the runner who was behind takes the lead.	Easy3	SimulationArray	No attempts yet	8s	1024 MB	Judgeable
Treasure HuntGiven treasure positions L and R and a start S, find the step where Dabin's zigzag search first lands on L or R.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Changes in Club MembershipGiven yearly counts of new members, where each cohort stays in the club for three years, find the largest membership in any year.	Easy3	ArraySliding window	No attempts yet	8s	1024 MB	Judgeable
Simple EditorApply each keystroke in order (insert a lowercase letter left of the cursor, or move the cursor left or right) and print the final string for each dataset.	Easy3	StackSimulation+1	No attempts yet	8s	1024 MB	Judgeable
Not PlayStationGiven a string of uppercase letters and digits, delete digits so that neither PS4 nor PS5 appears, keeping the longest such result.	Easy3	StringSimulation	No attempts yet	1s	1024 MB	Judgeable
Card Game (Easy)Given sorted attack values and H hit points, find the most cards you can attack with before the opponent dies, or -1 if they never die.	Easy3	GreedyPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Hyeongwon and the Curious SequenceGiven N, compute A_N, where A_0 is 0 and each step subtracts i from the previous value unless the result is negative or already used, in which case it adds i.	Easy3	SimulationHash map	No attempts yet	0.1s	1024 MB	Judgeable
Stacking CupsCount the ways to pick cups from N kinds, each in unlimited supply, so their rim heights sum to exactly H, modulo 1000000007.	Easy3	Dynamic programming	No attempts yet	1s	1024 MB	Judgeable
Dangling ElseRewrite a token sequence of if and else statements, where each else pairs with the nearest if, so that every body is wrapped in braces.	Easy3	RecursionImplementation	No attempts yet	2s	1024 MB	Judgeable
Dream, Passion, SharingPick Jaewon plus up to M-1 students whose stat totals do not exceed his own, so the team's combined total is maximized.	Easy3	GreedySorting	No attempts yet	2s	1024 MB	Judgeable
Questions Keep ComingEach question asks whether all earlier answers in a range x to y were Yes or all were No, and the task is to output the true answer to every question.	Easy3	ArrayPrefix sum	No attempts yet	1s	1024 MB	Judgeable
Events are coming (Easy)Given times T with forbidden open intervals (A, B), find the minimum distance Minjeong walks from 0 at speed at most 1 to avoid them, or report -1.	Easy3	Dynamic programmingSimulation	No attempts yet	1s	1024 MB	Judgeable
Abo and KINTEXGiven a string S of length N, count the distinct strings formed by inserting exactly one lowercase letter at the front, back, or between two characters of S.	Easy3	StringImplementation	No attempts yet	1s	1024 MB	Judgeable
Light ray polygonGiven the angles of incidence at mirrors A_1 to A_n of a convex polygon, the task is to find the angle at the laser pointer A_0.	Easy3	MathGeometry	No attempts yet	1s	1024 MB	Judgeable
Bingo BlockingFind the fewest cells to paint on an N by N grid so that every row, every column, and both length-N diagonals contain at least one painted cell.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
PyramidsGiven two equal-length ranges of arrays A and B, decide whether A[L..R] can be turned into B[X..Y] by moving stones between adjacent pyramids.	Easy3	Prefix sumArray	No attempts yet	1s	1024 MB	Judgeable
Binary Sorting (Easy)Given a binary string of length N, find its 0-based position after all length-N binary strings are sorted by popcount, then by their reversed value.	Easy3	Bit manipulationSorting	No attempts yet	1s	1024 MB	Judgeable
Difference between x and x+1Given x, list every k up to x where floor(x/k) and floor((x+1)/k) differ, which happens exactly when k divides x+1.	Easy3	Number theoryMath	No attempts yet	2s	1024 MB	Judgeable
Injured ShoulderGiven a dictionary and typed words, print 1 if a word is in the dictionary, 2 if it is two dictionary words joined without a space, and 0 otherwise.	Easy3	StringHash map	No attempts yet	5s	1024 MB	Judgeable
Hotel RoomsGiven n hotel rooms and a list of reservations, the task is to answer how many rooms in each queried range are still free.	Easy3	Segment treeArray	No attempts yet	1s	1024 MB	Judgeable
Troublesome KeysGiven the keys Alex pressed and the letters shown on screen, find the silly key with its wrong displayed letter and the quiet key, or report a dash if no quiet key was pressed.	Easy3	SimulationString+1	No attempts yet	1s	1024 MB	Judgeable
Efficient InspectionOn a tree, find the shortest closed walk from node 0 that visits every required node, and print its length and the route taken.	Easy3	TreeDFS	No attempts yet	1s	1024 MB	Judgeable
Drop the BitGiven N and the counts of 1 bits in two N-bit binary numbers x and y, find the maximum possible value of x XOR y.	Easy3	MathGreedy	No attempts yet	1s	1024 MB	Judgeable
Artifact ExcavationGiven the fragment coordinates of each artifact, find the artifact whose bounding rectangle has the largest area, breaking ties by smallest number.	Easy3	ArrayImplementation	No attempts yet	1s	1024 MB	Judgeable
Honggik UniversityCount the ways to split a word into contiguous segments that each contain exactly one vowel, modulo 10^9+7, or print -1 if the word has no vowels.	Easy3	StringMath	No attempts yet	1s	1024 MB	Judgeable
Space ArcheryGiven two axis-aligned cuboids, find the first frame where an arrow moving in the negative z direction overlaps the fixed target with positive volume, or -1 if never.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Double PalindromeCount ordered pairs of distinct strings where both X and Y are palindromes, because X1 Y X2 is a palindrome exactly then.	Easy3	StringMath	No attempts yet	1s	1024 MB	Judgeable
Heavy-Light CompositionGiven lowercase strings, check whether each string's letters alternate between light (appearing once) and heavy (appearing more than once).	Easy3	StringHash map	No attempts yet	1s	1024 MB	Judgeable
RookGiven a rook at (0,0), a target pawn at (a,b), and a friendly blocker at (x,y), find the fewest rook moves needed to capture the target.	Easy3	ImplementationMath	No attempts yet	1s	1024 MB	Judgeable
Toy LockDetermine whether a sequence can be sorted into ascending order when swaps are allowed only between positions exactly k apart.	Easy3	MathArray	No attempts yet	1s	1024 MB	Judgeable
\frac{1}{2}(MatKor+ALPS)=AlKorGiven N, output N+1 distinct integers where the last one equals the average of the first N.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Guess the Algorithms That Will Appear at KCPCGiven N problems, each with a list of tags, print the tag that appears on the most problems, or -1 if several tags tie for the top count.	Easy3	Hash mapString	No attempts yet	1s	1024 MB	Judgeable
Synchronizing Bulb PeriodsGiven N bulb periods and a target time T, find the fewest 1-second adjustments needed so that every period becomes a divisor of T.	Easy3	Number theoryImplementation	No attempts yet	1s	1024 MB	Judgeable
Enigma of the Jewelry CaseGiven an N by N grid that may have been rotated clockwise several times, find how many counterclockwise 90-degree turns restore the original orientation.	Easy3	MatrixImplementation	No attempts yet	1s	1024 MB	Judgeable
Kingdom's Development PlanGiven n projects and prerequisite pairs, output the lexicographically smallest valid completion order, or IMPOSSIBLE if the dependencies contain a cycle.	Easy3	Topological sortGraph+1	No attempts yet	2s	1024 MB	Judgeable
Alien Attack 2Given a friendship graph, find the size of the largest connected group, since each person's friends must be abducted together.	Easy3	GraphUnion-find+1	No attempts yet	4s	1024 MB	Judgeable
Bookshelf BottleneckEach book can be rotated so one side is at most H tall, and the task is to find the minimum total shelf width needed to place all n books in a line.	Easy3	ImplementationGreedy	No attempts yet	3s	1024 MB	Judgeable
Musical MendingGiven each key's pitch offset from the first key, find the minimal total absolute pitch change needed so consecutive keys differ by exactly one step.	Easy3	SortingMath+1	No attempts yet	2s	1024 MB	Judgeable
Light UpGiven an n by n Light Up grid with bulbs placed, the task checks whether every open cell is lit, no bulbs see each other, and every numbered wall has the right bulb count.	Easy3	MatrixSimulation+1	No attempts yet	1s	1024 MB	Judgeable
Raehwan's Mission to Get a GirlfriendGiven daily weight losses A_i, find the latest start day s such that dieting every day from s through N loses at least M units, or -1 if no start day works.	Easy3	Prefix sumTwo pointers	No attempts yet	1s	1024 MB	Judgeable
Rehwan's Big Taxi PlanGiven N desired departure times in HH:MM, find the fewest taxis, each carrying at most 3 students whose times fall within 10 minutes of each other.	Easy3	GreedySorting	No attempts yet	1s	1024 MB	Judgeable
HierarchyAfter each edge reversal, report whether the directed tree of superior-subordinate edges is a valid hierarchy with one root.	Easy3	GraphArray+1	No attempts yet	1s	1024 MB	Judgeable
Dialling DigitsGiven a sorted word list and phone numbers, list for each number the words whose keypad digits spell that number, in alphabetical order.	Easy3	Hash mapString	No attempts yet	2s	1024 MB	Judgeable
Human PyramidGiven n people, find the tallest human pyramid they can build, where a pyramid of height h needs h(h+1)/2 people.	Easy3	MathBinary search	No attempts yet	1s	1024 MB	Judgeable
Knitting PatternGiven N loops and a pattern of P loops, find how many loops stay empty at the back when patterns are placed symmetrically around the front.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Flag BearerDecode each 9x9 semaphore diagram into a letter, then shift every letter forward by C positions in the alphabet, wrapping around, and print the encrypted word.	Easy3	ImplementationString	No attempts yet	1s	1024 MB	Judgeable
Flag RotationGiven the stripe colours of a square flag, count the cells to repaint so the row stripes match the columns of a counter-clockwise rotation.	Easy3	Hash mapArray	No attempts yet	2s	1024 MB	Judgeable
Road to SPCGiven home, venue, and one blocked point, find the fewest turns in an axis-parallel walk from home to the venue.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Cascade CentralityGiven a tree, find the mean cascade centrality of its nodes, where each path adds the reciprocal of the product of degrees along it.	Easy3	TreeDFS+1	No attempts yet	1s	1024 MB	Judgeable
ConnectednessGiven N vertices and M edges added in order, find how many edges are drawn when the graph first becomes connected, or -1 if it never does.	Easy3	Union-findGraph	No attempts yet	1s	1024 MB	Judgeable
Garage Door CodeFind every K-digit code that appears as a subsequence of each observed keypad entry, and print them in sorted order.	Easy3	Brute forceString matching+1	No attempts yet	4s	1024 MB	Judgeable
Lego Lover's TriangleGiven the height and base of a triangular wall built from offset 2x4 Lego bricks, find the maximum number of whole bricks the wall can use.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Pascal MultipleCount the entries C(i,j) in the first N+1 rows of Pascal's triangle that are divisible by K, for given N and K.	Easy3	Dynamic programmingMath	No attempts yet	1s	1024 MB	Judgeable
Split into Odd or Split into Even!Given a sequence of positive integers, decide whether it can be split into an odd number of sets with odd sums, or an even number of sets with even sums.	Easy3	MathArray	No attempts yet	1s	1024 MB	Judgeable
Counting Cross Shapes in a GridCount the cells of an N by M binary grid that center a cross of size K, meaning all cells K steps up, down, left, and right are 1.	Easy3	MatrixPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
NumbersGiven the numbers players want, list every number between the smallest and largest wanted number that no player wanted.	Easy3	SortingArray+1	No attempts yet	1s	1024 MB	Judgeable
DifferencesGiven N scores, the task is to sum the absolute differences over all pairs of scores efficiently.	Easy3	SortingPrefix sum+1	No attempts yet	1s	1024 MB	Judgeable
Solving SõnasnäkkGiven a list of available letters and allowed words, print each word that can be spelled using the letters, using each letter at most once, in input order.	Easy3	StringHash map	No attempts yet	1s	1024 MB	Judgeable
Is it a sequence?Given an array, check whether rearranging only the elements from index L to R can make the whole array non-decreasing.	Easy3	ArrayImplementation	No attempts yet	1s	1024 MB	Judgeable
Sequence, AgainGiven N and K, build a sequence where each of 1 to N appears K times and every prefix of length i below N*K sums to i, or print -1 if impossible.	Easy3	MathImplementation	No attempts yet	1s	1024 MB	Judgeable
Big IntegersFor each pair of base 62 strings, check whether lexicographic order matches numeric order and print YES or NO.	Easy3	StringImplementation	No attempts yet	2s	2048 MB	Judgeable
A Stack of GoldGiven the scale reading w and stack count s, find which stack holds gold, when stack i contributes i coins and each gold coin adds 110 mg over tungsten.	Easy3	MathImplementation	No attempts yet	1s	2048 MB	Judgeable
Welcome SignCenter each of r words in a row of c columns, alternating the extra blank so the left gap is smaller on odd rows and larger on even rows.	Easy3	StringImplementation+1	No attempts yet	1s	2048 MB	Judgeable
Office BuildingGiven a grid of tree ages and a connected building shape that may be rotated but not flipped, find the placement that cuts down the least total age.	Easy3	Brute forceMatrix+1	No attempts yet	1s	2048 MB	Judgeable
Nobody Like ThatGiven a sequence of form submissions and payments, print the numbers of members who paid but still have not submitted the form after S other members submitted theirs since their payment.	Easy3	SimulationArray	No attempts yet	1s	1024 MB	Judgeable
Restore the permutationGiven an N by N comparison matrix, restore a permutation that produces it, or print -1 if no permutation matches.	Easy3	MatrixSorting+1	No attempts yet	2s	1024 MB	Judgeable
PianoGiven N keys to press in order and a hand span K, find the fewest hand moves needed, where the starting position is free.	Easy3	GreedyArray	No attempts yet	1s	1024 MB	Judgeable
ParadoxSimulate a five-player card game over N rounds and count the paradoxes, where a player replays a used card or plays a color they have already run out of.	Easy3	SimulationImplementation	No attempts yet	1s	1024 MB	Judgeable
Ordinal NumberGiven a nested set written with braces, print the integer n it encodes, where the set for n has exactly n elements.	Easy3	RecursionString+1	No attempts yet	2s	2048 MB	Judgeable
Faulty Traffic LightGiven which segments of a two-digit countdown light work, find the longest run of seconds where broken segments make the light look like it counts up by 1.	Easy3	Brute forceImplementation	No attempts yet	2s	2048 MB	Judgeable