Problems
Pick a problem and write your solution in the built-in editor. The judge runs it against real test cases while you watch, and the wider archive is open to read whenever you like.
Total results2,994 problems
| Title | Level | Topics | Solved | Time limit | Memory limit | Judge |
|---|---|---|---|---|---|---|
| Pattern Word BankingAdd the PIN digits picked by lowercase pattern letters and print non sequitur if the letter values do not match the PIN length. | Easy2 | SimulationString | No attempts yet | 2s | 256 MB | Judgeable |
| Secret MessagePad each message with asterisks to a square, rotate the square 90 degrees clockwise, then read it row by row without asterisks. | Easy2 | MatrixSimulation | No attempts yet | 2s | 256 MB | Judgeable |
| Negative People in Da HouseGiven each test case's sequence of entries and exits, compute the smallest initial occupancy that keeps the count nonnegative throughout. | Easy2 | Prefix sumSimulation | No attempts yet | 1s | 256 MB | Judgeable |
| Toilet Seat PoliciesCount seat moves under leave-up, leave-down, and leave-as-preferred policies given the initial seat position and each person in order. | Easy2 | Simulation | No attempts yet | 1s | 256 MB | Judgeable |
| GraphsPrint the equation line and an 11-column asterisk grid showing the y axis, the x axis, and the line y = Ax + B for each test case. | Easy2 | ImplementationSimulation | No attempts yet | 1s | 256 MB | Judgeable |
| SolitaireSimulate token moves on cells 0 to N with a repeating six-roll generator and sum landed values until reaching N. | Easy2 | Simulation | No attempts yet | 1s | 256 MB | Judgeable |
| Orc PopulationGiven two consecutive yearly populations and c, print the population c years later where each year equals the sum of the two before it. | Easy2 | ImplementationSimulation | No attempts yet | 1s | 256 MB | Judgeable |
| Distribution in MetagoniaRepeatedly peel off 2^a times the largest power of 3 fitting the odd part of the remainder until it hits zero, then print the pieces sorted. | Easy2 | SimulationMath+1 | No attempts yet | 2s | 256 MB | Judgeable |
| Mountain BikingFor each segment top, starting from rest, accumulate slope acceleration to compute the arrival speed at the foot. | Easy2 | MathSimulation | No attempts yet | 1s | 256 MB | Judgeable |
| Hidden PasswordDecide if scanning the message and skipping letters outside the remaining password set reproduces the password in order. | Easy2 | SimulationString | No attempts yet | 1s | 256 MB | Judgeable |
| D as in DaedalusGiven each round budget and the cards played, compute the extra points the first player could have won by playing the best card each round. | Easy2 | Simulation | No attempts yet | 3s | 256 MB | Judgeable |
| Magic TrickCount how many starting values from 1 to 100 turn negative or fractional when the given operations are applied in order. | Easy2 | SimulationBrute force | No attempts yet | 2s | 256 MB | Judgeable |
| Easy ProblemsetSimulate judges proposing problems in turn and keep each proposal whose hardness reaches the running total until k problems are chosen. | Easy2 | Simulation | No attempts yet | 1s | 256 MB | Judgeable |
| Tiling recordGiven a floor tiled with 1 by n tiles labeled by number, list each tile as h or v in row-major order of its first cell. | Easy2 | SimulationMatrix+1 | No attempts yet | 1s | 256 MB | Judgeable |
| Donation PackagingTrack the stock of three relief sets day by day, ship every packable trio once at least 30 are ready, and print the shipped count or NO. | Easy2 | SimulationMath | No attempts yet | 1s | 256 MB | Judgeable |
| YODACompare two numbers digit by digit from the right and drop the smaller digit at each position, printing YODA for a number left with no digits. | Easy2 | StringSimulation | No attempts yet | 1s | 64 MB | Judgeable |
| Nothing but BallsGiven N pitches of balls, hit batters, and wild pitches, simulate the runners on base and count the runs scored. | Easy2 | Simulation | No attempts yet | 1s | 64 MB | Judgeable |
| Number tag exchangeSimulate M bubble passes over the line, swapping neighbors when the front tag has the larger remainder modulo the pass number. | Easy2 | SimulationImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| Speed ViolationTwo speed profiles split the same 100 km road at different points, and you report the largest amount by which the driven speed exceeds the limit. | Easy2 | Two pointersSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| Circular BarnChoose the entry room on a circular barn so cows walking clockwise to their assigned rooms cover the smallest total distance. | Easy2 | Brute forceSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| Dance Around the Clock (Small)Simulate up to 10 rounds of alternating pairwise swaps around a circle of at most 10 dancers and report the two neighbors of dancer K. | Easy2 | Simulation | No attempts yet | 5s | 512 MB | Judgeable |
| Moist's Card SortingCount the cards a robot moves while it insertion sorts each deck of names into lexicographic order. | Easy2 | SimulationSorting | No attempts yet | 5s | 512 MB | Judgeable |
| Read Phone Number (Small)Split each digit string into the given group lengths and read each run of equal digits with count words such as double and triple. | Easy2 | SimulationString+1 | No attempts yet | 5s | 512 MB | Judgeable |
| Hedgemony (Small)Simulate a single left-to-right pass that trims each bush to the average of its current neighbors and output the final height of bush N-1. | Easy2 | SimulationMath | No attempts yet | 5s | 512 MB | Judgeable |
| Card Shuffle (Small)Simulate C segment-to-top cuts on a deck of M ordered cards and report the card at position W. | Easy2 | SimulationArray | No attempts yet | 5s | 512 MB | Judgeable |
| T9 Spelling (Small)Map each letter of a short message to its keypad digit and repeat count, inserting a space between consecutive letters that share the same key. | Easy2 | StringImplementation+2 | No attempts yet | 5s | 512 MB | Judgeable |
| Changyong's ClockTrack a clock's time on a 24-hour dial, turning it forward or backward by c seconds and answering queries for the current time. | Easy2 | SimulationMath+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Router 4Print the fixed two-layer router built from N inputs, r merge nodes, r split nodes, and N outputs, with M = 2N + r^2 connections. | Easy2 | ImplementationSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| Chop CupTrack which of three cups hides the ball after a sequence of swaps given as letters A, B, and C. | Easy2 | SimulationImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| Collatz SequenceStarting from n, repeatedly apply the Collatz rule (halve evens, 3n+1 for odds) and print every value from n down to 1 on one line. | Easy2 | SimulationImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| ChessboardPrint an N by M grid of asterisks and dots where the top left cell is an asterisk and adjacent cells always differ. | Easy2 | ArrayImplementation+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Sub-primeGiven each bank's reserve and a list of debentures between banks, check whether every bank ends with a nonnegative balance after all debentures settle at once. | Easy2 | ArrayImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| HolesCount the holes in each of N lines of uppercase text, where B counts as two, A D O P Q R count as one, and the rest count as zero. | Easy2 | StringImplementation+2 | No attempts yet | 2s | 512 MB | Judgeable |
| VirusGiven a key and one line of ciphertext, undo a Caesar variant whose shift grows by one per letter and resets after 25. | Easy2 | StringSimulation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Alpha PuzzleAssign numbers 1 to 26 to letters by scanning the grid and numbering each letter at its first appearance. | Easy2 | SimulationString+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Farm robot scarecrowCount how many times a robot moving clockwise or counter-clockwise around N stations visits a given station, starting at station 1. | Easy2 | SimulationImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| Luhn AlgorithmGiven a sixteen-digit card number as a string, check whether it passes the Luhn checksum and print DA or NE. | Easy2 | StringImplementation+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Counting Sheep (Large)For each N, find the first multiple of N that contains all ten digits, or report that no such multiple exists (only N = 0). | Easy2 | MathSimulation+1 | No attempts yet | 5s | 512 MB | Judgeable |
| MicrowaveGiven a start temperature below target, compute total heating time using per-degree rates for frozen and unfrozen states plus a fixed thawing time. | Easy2 | MathImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Grid PatternFor each case, print a text grid with pipe, minus, and plus lines and asterisk-filled cells of size w by h. | Easy2 | ImplementationSimulation+1 | No attempts yet | 10s | 512 MB | Judgeable |
| Speed LimitFor each log entry, multiply the speed by the time since the previous entry, sum these products, and print the total distance in miles. | Easy2 | ImplementationMath+1 | No attempts yet | 5s | 512 MB | Judgeable |
| Outer Triangle SumFor each triangle, add the first and last value of every row plus all values of the last row, counting shared corners once, and print the total. | Easy2 | ImplementationArray+2 | No attempts yet | 10s | 512 MB | Judgeable |
| X X gluedFor each registration number, print every run of two or more identical digits in the four-digit group, in left-to-right order. | Easy2 | StringImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| We Lost Again TodayGiven the runs each team scored in all nine innings, decide whether the Ullim Geminis ever held a lead during a game they ended up losing. | Easy2 | ImplementationSimulation+1 | No attempts yet | 1s | 64 MB | Judgeable |
| EmpathyMultiply two binary numbers up to 30 bits long and print the product in binary without leading zeros. | Easy2 | MathString+2 | No attempts yet | 2s | 256 MB | Judgeable |
| Jeonbuk National UniversityPrint an ASCII symbol of width N when N is odd, following fixed spacing rules; print "I LOVE CBNU" when N is even. | Easy2 | ImplementationSimulation | No attempts yet | 1s | 128 MB | Judgeable |
| I am happy~Given the height N, width M, and a seat number K in row-major order, print the row and column of that seat. | Easy2 | MathImplementation+2 | No attempts yet | 2s | 256 MB | Judgeable |
| Paint EstimateFor each floor plan, compute the paintable wall and ceiling area minus window and door areas, multiply by the number of apartments, and round the total up by the coverage of one can. | Easy2 | MathImplementation+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Advertising RevenueFor each data set, sum the payments for every display ad shown and every clickthrough ad clicked, then print the total. | Easy2 | ImplementationSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| The 3n+1 SequenceStarting from the given first term, apply the 3n+1 rule until the value first hits 1 and report that position. | Easy2 | SimulationMath+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Von Neumann and the FlyGiven train speed S, fly speed T, and initial gap D, compute how far the fly travels before the two trains collide. | Easy2 | MathImplementation+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Arggggggh!Follow a start point and a series of compass moves to compute the final coordinates, rounded to 8 decimals. | Easy2 | ImplementationMath+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Nine KnightsGiven a 5x5 board, check whether it has exactly nine knights with no two attacking each other. | Easy2 | ImplementationSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| Batter UpRead n at-bat outcomes, sum the bases from official at-bats (0 to 4), divide by how many of them are not walks, and print the result to six decimals. | Easy2 | ImplementationMath+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Latin SquaresRead an n by n grid of base-n digit characters and report whether it is a Latin square, and if so whether it is in reduced form. | Easy2 | ImplementationArray+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Atomic MassParse a short chemical formula, look up each element's atomic mass, multiply by any following count, and print the total with two decimals. | Easy2 | StringHash map+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Incomplete BookGiven the first book takes k days and each later book takes twice the previous, count how many books finish by day d. | Easy2 | MathSimulation+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Analysis of Advanced AnalyticsGiven daily page counts and a fixed notebook size, count how many notebooks are needed when each day's notes must fit in one notebook without splitting. | Easy2 | SimulationGreedy+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Grass CuttingAfter each week every cell grows 1 cm, then cells in the chosen rows and columns are reset to 1 cm; report the final heights of the 10x10 grid. | Easy2 | SimulationImplementation+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Jousting TournamentPrint the fixed elimination schedule that pits competitors 1..n one by one, alternating winners between placeholders a and b. | Easy2 | ImplementationSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| Kiwis vs KangaroosGiven a phrase, score each side by how often its letters appear in KANGAROO or KIWIBIRD, then report the higher score or a tie. | Easy2 | ImplementationString+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Recently Used DocumentsSimulate a most-recently-used list of capacity k: each opened document moves to the front, new ones are inserted there and the back is dropped when full, then print the final list. | Easy2 | SimulationImplementation+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Opening CeremonyFor each data set, count how many athletes from each country marched, then report the largest shortfall against that country's registered total. | Easy2 | ArrayImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Santa's GiftsCompute the total straight-line distance from Santa's house through four given points in 3D and check it does not exceed the time limit X. | Easy2 | MathGeometry+2 | No attempts yet | 5s | 512 MB | Judgeable |
| Big number A+BRead two integers with up to 10000 digits and print their sum without leading zeros. | Easy2 | StringMath+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Master of the Shell GameGiven a string, perform T swaps of characters at the given 0-indexed positions in order and print the final string. | Easy2 | StringSimulation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| It Worked, So Why Is It Wrong?Compare the expected answer with Manyoung's output for each sample and system test case, then print Accepted, Wrong Answer, or Why Wrong!!! according to which group fails. | Easy2 | ImplementationSimulation+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Mannequins on the Tracks!!Simulate a trolley moving through three zones under a sequence of wait and lever-pull actions, and count how many mannequins get run over in zone C. | Easy2 | SimulationImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| LukaGiven Luka's fixed position and a walk of unit steps, list the indices of steps after which the walker stands on Luka's cell or one of the eight neighbors. | Easy2 | ImplementationSimulation | No attempts yet | 1s | 512 MB | Judgeable |
| Unraveling Monty HallCount how many of N trials hide the car behind door 2 or 3, since switching from door 1 wins exactly then. | Easy2 | MathSimulation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Run-Length Encoding, Run!Encode a string as run-length pairs, or decode run-length pairs back to the original string. | Easy2 | StringSimulation | No attempts yet | 2s | 512 MB | Judgeable |
| Mixing MilkSimulate 100 cyclic pours among three buckets, each pour moving as much milk as fits until the source empties or the target fills, and print the final amounts. | Easy2 | SimulationImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| ElderTrack which wizard owns the Elder Wand after each duel and count how many distinct wizards ever held it. | Easy2 | SimulationImplementation+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Magnet ChainGiven up to 5 magnets as a 1/2 sequence, decide whether the chain is fully connected after at most one magnet flip. | Easy2 | ImplementationBrute force+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Physics HomeworkFor each test case, find the time at which car A, starting slower than car B and accelerating, reaches or passes car B's constant speed. | Easy2 | MathImplementation+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Vending MachineGiven a sequence of vending machine button presses with fixed prices, subtract the total cost from 5000 won and print the change. | Easy2 | ImplementationMath+1 | No attempts yet | 1s | 256 MB | Judgeable |
| 99 Bottles of BeerGiven N, print the full lyrics of the N Bottles of Beer song, with correct singular and plural wording. | Easy2 | ImplementationString+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Bonus ScoreGiven a string of O and X for N problems, compute the total score where problem i gives i points plus a running bonus that grows on each O and resets on each X. | Easy2 | ImplementationSimulation+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Missing NumbersGiven an increasing list of distinct numbers a child recited, print every integer from 1 up to the last recited number that is missing, or print "good job" if none are. | Easy2 | ArrayImplementation+2 | No attempts yet | 1s | 1024 MB | Judgeable |
| Simple Collatz SequenceSimulate the modified Collatz rule (halve even k, increment odd k) from n until reaching 1 and count the steps taken. | Easy2 | SimulationImplementation+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Hanging Out on the TerraceTrack how many people are on a terrace with a limit L and count how many enter groups are turned away because they would exceed it. | Easy2 | SimulationImplementation | No attempts yet | 1s | 512 MB | Judgeable |
| Jazz EnthusiastAdd up the lengths of n songs, subtract the crossfade time once for each pair of adjacent songs, and print the total as hh:mm:ss. | Easy2 | MathImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| I'll Pay, No I'll PayPeople take turns adding to their outstretched amount; find who first reaches the threshold K and on which of their turns. | Easy2 | SimulationImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| TimeCount how many clock times from 00:00:00 through N:59:59 contain the digit K at least once. | Easy2 | Brute forceImplementation+2 | No attempts yet | 1s | 256 MB | Judgeable |
| Space PokerGiven fixed counts of red, green, and blue chips and two coefficients, pick which single chip color to add to maximize a quadratic payout formula. | Easy2 | Brute forceMath+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Sum of a SequenceGiven N and a minimum length L, find the shortest run of consecutive non-negative integers summing to N, or print -1 if none exists within length 100. | Easy3 | MathBrute force+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Tournament Meeting RoundSimulate a single-elimination tournament where positions are halved each round to find when two specific players first face each other. | Easy3 | SimulationMath+1 | No attempts yet | 1s | 512 MB | Judgeable |
| KingMove a king on an 8x8 board by given commands; if it lands on the stone, the stone slides one square the same way unless it would leave the board. | Easy3 | SimulationImplementation | No attempts yet | 2s | 128 MB | Judgeable |
| Addition CycleSimulate a digit-transformation cycle on a two-digit number until it returns to the original value and count the steps. | Easy3 | SimulationMath | No attempts yet | 2s | 128 MB | Judgeable |
| Josephus PermutationSimulate the Josephus elimination order for N people counting off every K-th person in a circle and print the removal sequence. | Easy3 | QueueSimulation+1 | No attempts yet | 2s | 256 MB | Judgeable |
| Dice SumGiven three dice with sizes S1, S2, S3, find the sum value that occurs most often among all possible triples, choosing the smallest if tied. | Easy3 | Brute forceMath+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Switches On and OffSimulate switch toggles where male students flip every multiple of their number and female students flip the largest symmetric interval centered on their number. | Easy3 | SimulationArray+2 | No attempts yet | 2s | 128 MB | Judgeable |
| Binary AdditionAdd two binary strings up to 80 digits long and print the sum in binary without leading zeros. | Easy3 | StringMath+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Alphabet DiamondGiven a repeating diamond-pattern tile defined by N, print the characters inside a specified rectangular region of the infinite tiled plane. | Easy3 | SimulationMath+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Shortcut Key AssignmentAssign each menu option an unused shortcut letter by checking word-initial letters first, then any letter in the string, following the options in order. | Easy3 | SimulationString+1 | No attempts yet | 2s | 128 MB | Judgeable |
| 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 |
| 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 |
| 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 |