cho.sh

Curated sets

Interview warm-up

Short whiteboard tasks to get the rust off.

All problems
Total results2,493 problems
TopicsJudge
Uphill RoadGiven a sequence of heights, find the maximum height difference over the longest strictly increasing consecutive run.Easy2ArrayImplementationNo attempts yet1s128 MBJudgeable
Super MarioGiven 10 mushroom scores, pick a prefix sum closest to 100 (preferring the larger one on ties) as Mario's final score.Easy2ArrayBrute force+1No attempts yet1s128 MBJudgeable
Maximum Value of a Fraction TableGiven a 2x2 grid of positive integers, find how many 90-degree clockwise rotations (0-3) maximize A/C+B/D, choosing the smallest such count on ties.Easy2Brute forceImplementation+1No attempts yet1s128 MBJudgeable
Difference Between 5 and 6Given two integers, compute the minimum and maximum possible sums after freely swapping digits 5 and 6 in each number.Easy2StringGreedy+1No attempts yet1s128 MBJudgeable
Climbing SnailCompute the number of days for a snail climbing A meters by day and sliding B meters by night to reach a pole of height V.Easy2MathSimulationNo attempts yet0.25s128 MBJudgeable
Monster TruckCount 2x2 blocks in a grid without any building, grouped by how many parked cars they contain (0 to 4).Easy2MatrixImplementationNo attempts yet1s128 MBJudgeable
Why Is KMP Called KMP?Convert a hyphen-joined full name like Knuth-Morris-Pratt into its initials such as KMP.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
CopyrightGiven A songs and a rounded-up average I, find the smallest total copyrighted melodies consistent with ceil(total/A) = I.Easy2MathImplementationNo attempts yet1s128 MBJudgeable
DominoesGiven N, compute the total dot count across all unique dominoes with halves ranging from 0 to N.Easy2MathCombinatoricsNo attempts yet1s128 MBJudgeable
Year 2009Given a day and month in the year 2009, output the English name of the weekday for that date.Easy2MathImplementationNo attempts yet1s128 MBJudgeable
I Am a ChefGiven four scores each for five contestants, output the number and total score of the contestant with the highest sum.Easy2ArrayImplementationNo attempts yet1s128 MBJudgeable
Changyeong's DiaryDecode a string by replacing every vowel-p-vowel triple with the single vowel, restoring the original sentence.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
Answer Pattern GuessingGiven an answer string, count matches against three fixed repeating guess patterns and report the highest score and who achieved it.Easy2SimulationString+1No attempts yet1s128 MBJudgeable
ATM TransactionsProcess ATM withdrawal or deposit lines, updating balance but rejecting withdrawals that push it below -200, until a sentinel line ends input.Easy2SimulationImplementationNo attempts yet1s128 MBJudgeable
OctalConvert a binary string (up to 100 digits) to octal by padding and grouping bits in threes using the given table.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
Fourth PointGiven three corners of an axis-aligned rectangle, compute the coordinates of the missing fourth corner.Easy2GeometryMath+1No attempts yet1s128 MBJudgeable
Equal-Size Interval ClusteringSort points lexicographically, split them into K consecutive groups of nearly equal size, and print each group's coordinate average.Easy2SortingArray+1No attempts yet5s128 MBJudgeable
Changyeong Village Cup ShuffleTrack the position of a ball among three cups after a sequence of swap operations described by characters A, B, C.Easy2SimulationStringNo attempts yet1s128 MBJudgeable
Time Until the WarningGiven current time and a future warning time in a day, compute the wait time as a difference modulo 24 hours, printing 24:00:00 if they match.Easy2MathImplementationNo attempts yet1s128 MBJudgeable
Angry ChangyoungFor each match length, decide if it fits diagonally inside a W by H rectangle and print DA or NE accordingly.Easy2GeometryMath+1No attempts yet1s128 MBJudgeable
ScannerExpand an R by C character grid by repeating each character ZR times vertically and ZC times horizontally, then print the result.Easy2SimulationImplementation+1No attempts yet1s128 MBJudgeable
Snow White and the Seven DwarfsGiven nine distinct numbers, find and print in increasing order the seven of them that sum to exactly 100.Easy2Brute forceArrayNo attempts yet1s128 MBJudgeable
15-Puzzle DisplacementCompute the total Manhattan distance of each labeled tile from its position in the solved 4x4 15-puzzle board.Easy2ArrayMath+1No attempts yet1s128 MBJudgeable
Find the Even NumbersFor each test case with seven numbers, output the sum and minimum of the even ones among them.Easy2ArrayImplementationNo attempts yet1s128 MBJudgeable
Number ReversalFor each number, reverse its digits, add to the original, and print YES if the sum is a palindrome, else NO.Easy2StringMath+1No attempts yet1s128 MBJudgeable
Scaled ChessboardPrint a checkerboard of R by C cells where each cell is scaled to an A by B block of X or dot characters.Easy2SimulationImplementationNo attempts yet1s128 MBJudgeable
Making an AcronymBuild an acronym from the first letters of words in a phrase, skipping a fixed list of filler words unless one is the first word.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
BUHAGiven up to 100 square bomb-range constraints on an A by B grid, count how many cells satisfy all the inside/outside conditions.Easy2ArraySimulation+1No attempts yet1s128 MBJudgeable
Vigenère Cipher EncryptionEncrypt repeated plaintext lines with a repeating key using a shifted Vigenère cipher until a line with 0 appears.Easy2StringSimulation+1No attempts yet1s128 MBJudgeable
Hamming DistanceFor each test case, count the positions where two equal-length binary strings differ and print the Hamming distance.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
Binary NumberFor each given integer, output the positions of all bits set to 1 in its binary representation, from least to most significant.Easy2Bit manipulationImplementationNo attempts yet1s128 MBJudgeable
Hyunwoo the ProfessorFor each given N, output the number of trailing zeros in N! by counting factors of 5.Easy2MathNo attempts yet1s128 MBJudgeable
Automated Telephone ExchangeGiven a 3-digit exchange index n, count pairs of two-digit numbers a,b (00-99) such that n - a - b = 0.Easy2Brute forceMathNo attempts yet1s128 MBJudgeable
ElectrificationGiven switch-to-lamp toggle mappings and a sequence of switch flips, compute and print the final on/off state of each lamp using parity counting.Easy2SimulationBit manipulationNo attempts yet2s256 MBJudgeable
FlatGiven room areas and types, compute total area, total bedroom area, and flat cost using half-weighted balcony area.Easy2ImplementationMathNo attempts yet3s256 MBJudgeable
K-Graph OddityCompute the maximum vertex degree in a graph and output the smallest odd integer greater than or equal to it.Easy2GraphImplementation+1No attempts yet1s128 MBJudgeable
Explicit FormulaGiven 10 binary inputs, evaluate a fixed XOR-of-ORs boolean formula (equivalently just count pairs/triplets with at least one 1 and check parity) and output the result.Easy2Bit manipulationImplementation+1No attempts yet3s256 MBJudgeable
Cutting a BlockGiven a box and n, print the coordinates of n equal slabs formed by evenly spaced cuts along the x-axis, each rounded to 8 decimals.Easy2MathSimulation+1No attempts yet2s64 MBJudgeable
Anagram DistanceGiven many word pairs, count letters to delete from both so their letter frequency histograms match, using character counts.Easy2Hash mapString+1No attempts yet1s256 MBJudgeable
MinesweeperGiven a grid of mines and empty cells, replace each empty cell with the count of mines in its eight neighbors.Easy2SimulationImplementation+2No attempts yet1s128 MBJudgeable
Right TriangleRead triples of side lengths until 0 0 0, and print right if the squares of the two shorter sides sum to the square of the longest, else wrong.Easy2MathImplementation+2No attempts yet1s128 MBJudgeable
LogoTrack a turtle's position and heading through forward, backward, left, and right commands, then report the rounded distance from the start.Easy2SimulationGeometry+2No attempts yet1s128 MBJudgeable
Prerequisites?Given Freddie's chosen courses and category minimums, check whether each category has at least the required number of his courses.Easy2ImplementationHash map+2No attempts yet1s128 MBJudgeable
AFC WimbledonGiven the sum and difference of two non-negative scores, print the larger score first, or -1 if no such scores exist.Easy2MathImplementation+1No attempts yet1s128 MBJudgeable
Combination LockGiven the dial position and three combination numbers, sum the degrees turned clockwise and counter-clockwise to open the lock.Easy2SimulationMath+1No attempts yet1s128 MBJudgeable
Hay PointsSum dictionary values of words appearing in each job description line block until a single period terminates it.Easy2Hash mapStringNo attempts yet1s128 MBJudgeable
BabelfishBuild a foreign-to-English word dictionary from the input, then translate each foreign word in the message, printing eh for unknown words.Easy2Hash mapString+1No attempts yet1s128 MBJudgeable
Always Follow the Rules in ZombielandRead q quotes in order, then answer r lookups by printing the quote at that 1-based index, or "No such rule" if out of range.Easy2ArrayImplementation+1No attempts yet1s128 MBJudgeable
Bubble Gum, Bubble Gum, in the Dish, How Many Pieces Do You Wish?Given a list of names arranged in a circle, a starting person, and a count n, find who is at position n in the count.Easy2ArraySimulation+1No attempts yet1s128 MBJudgeable
Number Card GameFor each starting number S, repeatedly replace it with the product of its digits until a single digit appears, printing every value in order.Easy2SimulationImplementation+2No attempts yet1s128 MBJudgeable
Refrigerator MagnetsRead lines until END and print each line that contains no repeated letter, ignoring spaces.Easy2ImplementationString+2No attempts yet1s128 MBJudgeable
Mirror ImageFor each word until the terminator '#', print the string reversed with each letter replaced by its mirror image, or INVALID if any letter lacks a mirror.Easy2StringHash map+1No attempts yet1s128 MBJudgeable
Gnome SequencingFor each of N triples of beard lengths, decide whether the three values are strictly increasing or strictly decreasing, then print Ordered or Unordered.Easy2ImplementationSorting+2No attempts yet1s128 MBJudgeable
ParityRead bit strings whose last bit is missing plus a parity letter, and append the 0 or 1 that makes the parity match.Easy2StringBit manipulation+1No attempts yet1s128 MBJudgeable
QuicksumCompute a weighted checksum for each input line: sum each character's 1-based position times its letter value, where spaces count as 0, until a line with only #.Easy2StringImplementation+2No attempts yet1s128 MBJudgeable
DoublesFor each list of 2 to 15 natural numbers ending in 0, count how many values x have 2x also in the same list.Easy2ArrayHash map+1No attempts yet1s128 MBJudgeable
Magnificent MeatballsGiven a circular list of guest meatball counts, find the position k where the sum of positions 1 through k equals the sum of the rest.Easy2ArrayPrefix sum+1No attempts yet1s128 MBJudgeable
Fifty Coats of GrayGiven room dimensions, opening sizes, and the area one can covers, compute the total paintable area for n apartments and round up to whole cans.Easy2MathImplementation+2No attempts yet1s128 MBJudgeable
Roaming RomansConvert each English-mile distance into Roman miles and paces using a fixed ratio, rounding the pace count to the nearest integer.Easy2MathImplementation+2No attempts yet1s128 MBJudgeable
Filling Out the TeamFor each player's speed, weight, and strength, print the positions whose limits the player satisfies, in table order, or No positions.Easy2ImplementationBrute force+1No attempts yet1s128 MBJudgeable
General Chemistry LabGiven a sequence of temperatures ending with 999, print each temperature's difference from the previous one, rounded to two decimals.Easy2ImplementationMath+1No attempts yet1s128 MBJudgeable
Cantor SetFor each N, print a line of 3^N characters following the Cantor set rule: each third-level block of size 3^k has its middle third blanked, dashes elsewhere.Easy2RecursionImplementation+2No attempts yet1s128 MBJudgeable
Next NumberGiven three distinct integers from an arithmetic or geometric progression, decide which type it is and print the label with the next term.Easy2MathImplementation+2No attempts yet1s128 MBJudgeable
Number Guessing GameFor each n0, report whether 3*n0 is odd or even and print n4, the quotient of (n2*3)/9.Easy2ImplementationMath+1No attempts yet1s128 MBJudgeable
Judging OlympiaFor each line of six judge grades, discard the highest and lowest and print the average of the remaining four, stopping at the all-zero line.Easy2ImplementationMath+1No attempts yet1s128 MBJudgeable
ICPC Score Totalizer SoftwareFor each contestant, drop one highest and one lowest judge score, then output the truncated average of the rest.Easy2ImplementationSorting+2No attempts yet1s128 MBJudgeable
SavingsFor each test case, print how many years of multiplying the balance by (1 + B/100) are needed until it first exceeds M.Easy2SimulationMath+2No attempts yet1s128 MBJudgeable
Ah!Compare two strings of the form a...ah and print go if the first has at least as many a characters as the second.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
Death Knight HeroCount how many of the given ability strings avoid the forbidden substring "CD".Easy2StringImplementation+1No attempts yet1s128 MBJudgeable
Jean and Joe's ClothesRead clothing sizes and count how many items go to Joe, Jean, Jane, James, or no one, per visit until N equals 0.Easy2ImplementationSimulation+2No attempts yet1s128 MBJudgeable
DVDsApply a series of clamped sale and restock transactions to each DVD title's stock and report the final count.Easy2ImplementationSimulation+2No attempts yet1s128 MBJudgeable
Oil ExplorationFor each column of a grid, scan downward and sum drilling costs (H costs 3, S costs 1) until the first oil cell, or print N if none exists.Easy2ArraySimulation+1No attempts yet1s128 MBJudgeable
Map InterfaceGiven station coordinates and a visited sequence, count how many stations fall inside the smallest axis-aligned rectangle covering the visited stations.Easy2ArrayImplementation+2No attempts yet1s128 MBJudgeable
Isn't It Funny How a Bear Likes Honey?Given Pooh's weight and the radii of several spherical helium balloons, decide whether their combined lift strictly exceeds his weight.Easy2MathImplementation+2No attempts yet1s128 MBJudgeable
Contest SeatsCount how many participants fail to get their chosen seat, since only the first arrival for a seat can sit there.Easy2ImplementationHash map+1No attempts yet1s128 MBJudgeable
Alphabet DistanceFor each test case, read two equal-length uppercase words and print the alphabet distance between the paired letters at every position.Easy2StringImplementation+1No attempts yet1s128 MBJudgeable
Vigenère CipherEncrypt each given plaintext with the Vigenère cipher, shifting every letter by the aligned repeated keyword letter modulo 26.Easy2StringImplementation+1No attempts yet1s128 MBJudgeable
Stacked Floating MountainsGiven several sequences, decide for each whether every element from the third onward equals the sum of the two before it.Easy2ImplementationArray+1No attempts yet1s128 MBJudgeable
Chess PuzzleFor each board, read the rook coordinates and report SAFE if no two rooks share a row or column, otherwise NOT SAFE.Easy2ImplementationHash map+2No attempts yet1s128 MBJudgeable
Checkerboard RowsFor each of B boards, read n pieces given as column-row pairs and print the largest number of pieces sharing the same row.Easy2ArrayHash map+1No attempts yet1s128 MBJudgeable
Counting Swann's CoinsPrint numbers 1 through N, replacing multiples of 3 with Dead, of 5 with Man, and of 15 with DeadMan, breaking the line after each word.Easy2ImplementationMath+1No attempts yet1s128 MBJudgeable
Secret LocationEach of six lines encodes one number by its character count; print the first three as Latitude and the last three as Longitude in the given format.Easy2StringImplementation+2No attempts yet1s128 MBJudgeable
Greatest Common DivisorRead n pairs of positive integers and print the greatest common divisor of each pair on its own line.Easy2MathNumber theory+1No attempts yet1s128 MBJudgeable
DedupeFor each of several strings, collapse every run of consecutive identical letters into a single letter and print the result.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
Football TeamRead names one per line and swap every i with e and every I with E in each name.Easy2StringImplementation+1No attempts yet1s128 MBJudgeable
Garbled MessageRead lines of garbled text until EOF and replace every occurrence of the substring "iiing" with "th", preserving all other characters and line breaks.Easy2StringImplementation+1No attempts yet1s128 MBJudgeable
YodaFor each sentence, move its first two words to the end and print the result.Easy2StringImplementationNo attempts yet1s128 MBJudgeable
Escape RouteGiven your position and n-1 planet positions, find the closest planet, print both coordinates, and print the distance rounded to two decimals.Easy2Brute forceMath+1No attempts yet1s128 MBJudgeable
Total CountRead fighter names until a line with 0, print each name with its kill count in first-appearance order, then the grand total.Easy2Hash mapImplementation+2No attempts yet1s128 MBJudgeable
Target PracticePrint an n by n square border with an X drawn across the inner grid using asterisks.Easy2ImplementationSimulationNo attempts yet1s128 MBJudgeable
Annoying MosquitosGiven up to 100 mosquito positions and up to 10000 swat centers, count how many mosquitos fall within the 101x101 square of at least one swat.Easy2Brute forceImplementation+1No attempts yet1s256 MBJudgeable
LeagueGiven every match result in a round-robin soccer league, compute each team's total points and print its rank, where tied teams share the best rank.Easy2ImplementationArray+2No attempts yet1s128 MBJudgeable
Dice GameSimulate a piece on a board of cells, applying a die roll then the cell's instruction, and report how many rolls reach the goal.Easy2SimulationArrayNo attempts yet1s128 MBJudgeable
Time CardGiven clock-in and clock-out times for three employees in h m s form, print each employee's working duration as hours, minutes, and seconds.Easy2MathImplementation+1No attempts yet1s128 MBJudgeable
ChangeGiven a purchase amount below 1000 yen paid with a 1000-yen bill, find the minimum number of coins in the change.Easy2GreedyMath+1No attempts yet1s128 MBJudgeable
Caesar CipherGiven an uppercase word encrypted by shifting each letter forward three positions, shift every letter back by three to recover the original.Easy2StringImplementation+2No attempts yet1s128 MBJudgeable
Card Flipping GameGiven two rows of n digit cards, reveal pairs left to right; the larger card wins both cards' sum, and equal cards each keep their own.Easy2SimulationImplementation+1No attempts yet1s128 MBJudgeable
Tunnel Entrance and ExitTrack the number of cars in a tunnel each minute from entrance and exit counts, and print the maximum count, or 0 if it ever goes negative.Easy2ImplementationSimulation+1No attempts yet1s128 MBJudgeable
BirthdayGiven each student's name and birthday, print the name of the youngest student, then the oldest.Easy2ImplementationSorting+1No attempts yet1s128 MBJudgeable
Hailstone SequencesFor each starting value H up to 500, simulate the Collatz rule and print the largest number that appears before reaching 1.Easy2SimulationImplementation+1No attempts yet1s128 MBJudgeable