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 results1,785 problems
| Title | Level | Topics | Solved | Time limit | Memory limit | Judge |
|---|---|---|---|---|---|---|
| PiratesGiven a lowercase word, find the letter with the highest frequency and print that letter with its count. | Easy2 | StringHash map+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Password checkFor each of N passwords, report valid if it has a lowercase letter, uppercase letter, digit, symbol, and length at least 12, else invalid. | Easy2 | StringImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| Hissing MicrophoneGiven a lowercase string, check whether it contains two consecutive s characters and print hiss or no hiss. | Easy2 | StringImplementation | No attempts yet | 1s | 512 MB | Judgeable |
| Life ScoreFor each name, sum the letter values (A=1 to Z=26, spaces worth 0) and print the total, or PERFECT LIFE when the total is exactly 100. | Easy2 | StringImplementation | No attempts yet | 2s | 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 |
| Check the CheckRead dish names and price-quantity pairs until the line TOTAL, then print PAY if the waiter's total is at most the sum of price times quantity, else PROTEST. | Easy2 | ImplementationString+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Lorem ipsumSplit a fixed Latin placeholder paragraph into words and print the words at indices L through R separated by spaces. | Easy2 | StringImplementation+1 | No attempts yet | 0.1s | 512 MB | Judgeable |
| Hash collision stringsPrint two length-N strings that differ but have equal Java String hashCode values, using the classic Aa/BB collision with a shared prefix. | Easy2 | StringHash map+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Binary GamePrint the binary representations of 0 through n, concatenated with no separators. | Easy2 | StringImplementation | No attempts yet | 1s | 256 MB | Judgeable |
| RickRead one line and print NO if it exactly matches one of six given phrases, otherwise print YES. | Easy2 | StringImplementation | No attempts yet | 1s | 256 MB | Judgeable |
| Derivative of a polynomial functionParse a linear polynomial written like 3x+5 or -x+2 and print the constant that is its derivative. | Easy2 | StringImplementation+1 | No attempts yet | 1s | 512 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 |
| What Is Your HandleSort N distinct handles by ASCII dictionary order and print the I-th one. | Easy2 | SortingString+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Caesar CipherShift every letter of a string by k positions in the alphabet, wrapping around, and leave spaces, periods, and commas unchanged. | Easy2 | StringImplementation+1 | No attempts yet | 1s | 64 MB | Judgeable |
| What Does UCPC Stand For?Given one string, decide whether deleting some characters can leave exactly the subsequence UCPC, case sensitive. | Easy2 | StringGreedy+1 | No attempts yet | 1s | 512 MB | Judgeable |
| Occupy ParkingCount how many of the N parking spaces show 'C' in both the yesterday string and the today string. | Easy2 | StringImplementation+1 | No attempts yet | 2s | 512 MB | Judgeable |
| Baby BitesGiven n spoken words that are either "mumble" or a number, check if the i-th number equals i and output "makes sense" or "something is fishy". | Easy2 | ImplementationString | No attempts yet | 1s | 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 |
| Time to DecompressRead L lines, each with a count N and a character, and print that character repeated N times on its own line. | Easy2 | StringImplementation | No attempts yet | 1s | 512 MB | Judgeable |
| XORChicGiven an XOR-encrypted string whose first 8 characters decode to "CHICKENS", recover the key and output the original string. | Easy2 | ImplementationBit manipulation+2 | 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 |
| Cute Number~ε٩(๑> ₃ <)۶зGiven an integer up to 10^18, check whether its digits form an arithmetic sequence with a constant difference, and print one of two fixed messages. | Easy2 | ImplementationMath+2 | No attempts yet | 1s | 512 MB | Judgeable |
| What's the Second Baseman's NameGiven up to 1000 player names, check whether any name equals the string anj and print one of two fixed messages. | Easy2 | ImplementationString | 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 |
| What Is a Recursive Function?Given N, print the chatbot message 'What is a recursive function?' repeated with nested quotation marks for N levels of recursion. | Easy2 | ImplementationString+1 | No attempts yet | 1s | 256 MB | Judgeable |
| 369Count the total claps in the 369 game from 1 to N, where each number contributes one clap per digit that is 3, 6, or 9. | Easy2 | ImplementationMath+2 | No attempts yet | 1s | 512 MB | Judgeable |
| Mangling NamesGiven a table of pronunciation times by vowel and consonant counts, sum the times for each student name and report the total. | Easy2 | ImplementationString+2 | No attempts yet | 2s | 512 MB | Judgeable |
| CommandFor each of T strings, decide whether it has length 7 and its characters follow the exact pattern AABBABB with exactly two distinct letters. | Easy2 | StringImplementation+1 | No attempts yet | 0.5s | 256 MB | Judgeable |
| Regional Team NamesDecide whether a string splits into an institution part of 2 to 8 characters, a hyphen, then a team name of 1 to 24 characters. | Easy2 | StringImplementation | No attempts yet | 1s | 512 MB | Judgeable |
| Pea Soup and PancakesRead each restaurant's name and menu, then print the first one serving both pea soup and pancakes, or a fixed fallback line if none does. | Easy2 | ImplementationString+2 | No attempts yet | 1s | 512 MB | Judgeable |
| ÖstgötskaCount how many space-separated words contain the substring "ae"; if that count is at least 40 percent of the words, print one fixed phrase, otherwise the other. | Easy2 | StringImplementation+1 | No attempts yet | 1s | 512 MB | Judgeable |
| TapiokaGiven a three-word dish name, remove the words "bubble" and "tapioka", then print the remaining words or "nothing" if none remain. | Easy2 | StringImplementation | No attempts yet | 2s | 1024 MB | Judgeable |
| Lucky StraightGiven an even-length number, decide whether the sum of its left-half digits equals the sum of its right-half digits, printing LUCKY or READY. | Easy2 | StringImplementation+2 | No attempts yet | 1s | 256 MB | Judgeable |
| CapitalizationReplace every occurrence of the substring "joi" in a lowercase string with "JOI" and print the result. | Easy2 | StringImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| BananaRead a dictionary mapping English words to Minionese words, then translate each of T sentences word by word. | Easy2 | Hash mapString+2 | No attempts yet | 2s | 512 MB | Judgeable |
| Divisionals SpellingGiven n words and a contest with m questions labeled A onward, count how many words use only distinct letters from the first m letters. | Easy2 | ImplementationString+1 | No attempts yet | 1s | 512 MB | Judgeable |
| RebusSplit the input into space-separated words, strip leading and trailing apostrophes by removing that many letters from each end, then concatenate the pieces. | Easy2 | StringImplementation | No attempts yet | 2s | 512 MB | Judgeable |
| Minimum String DifferenceSlide the shorter string A across every possible alignment position over B and output the minimum number of mismatched characters. | Easy3 | StringSliding window+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Strange MultiplicationGiven two large numbers as digit strings, compute the sum of all pairwise products of their digits, which equals the product of their digit sums. | Easy3 | MathString+1 | No attempts yet | 2s | 256 MB | Judgeable |
| Student NumbersGiven N equal-length numeric strings, find the smallest suffix length k so that all suffixes of length k remain distinct. | Easy3 | StringBrute force+1 | 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 |
| Make a PalindromeGiven a lowercase string of length at most 50, find the minimum length of a palindrome obtained by appending characters only to its end. | Easy3 | StringBrute force+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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| DNA Decoding 2Given a DNA string up to 20 million bases, repeatedly collapse the rightmost two characters using a lookup table until one base remains. | Easy3 | StringSimulation+1 | No attempts yet | 1s | 2 MB | Judgeable |
| Distinguishing FilesGiven N files as sequences padded with zeros, find the minimum prefix length K that makes all files pairwise distinct. | Easy3 | StringBrute force+1 | No attempts yet | 2s | 128 MB | Judgeable |
| SaschaGiven a pronounced word and a dictionary of same-length words, find the dictionary word with the minimum Hamming distance, breaking ties by input order. | Easy3 | StringBrute force+1 | No attempts yet | 2s | 128 MB | Judgeable |
| Secret LetterDecode a binary string into 6-bit chunks matching a fixed 8-letter code table by Hamming distance at most 1, printing the first unidentifiable chunk's position if any. | Easy3 | StringBrute force+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Similar WordsCount how many words differ from the first word's letter multiset by at most one insertion, deletion, or substitution. | Easy3 | Hash mapString+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Roman NumeralsConvert two Roman numerals to integers, sum them, and output the sum as both an Arabic and a Roman numeral. | Easy3 | StringMath+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Spreadsheet Cell NamesConvert given row and column numbers into spreadsheet-style cell names like A1 or BC23, stopping at R0C0. | Easy3 | MathString+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Window BlindsParse a grid of ASCII-drawn window blinds and count how many of the M×N windows show each of five possible blind heights. | Easy3 | SimulationImplementation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Make a CrosswordBuild a grid where word A is placed horizontally and word B vertically, crossing at the first shared letter following a defined scan rule, filling the rest with dots. | Easy3 | StringImplementation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Math HomeworkExtract every maximal run of digits from up to 100 strings, strip leading zeros, and print all extracted numbers sorted nondecreasing. | Easy3 | StringSorting+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Machine CodeGiven a sequence of instructions with parameters, compute the minimum NOPs needed so each instruction starts at an address divisible by 4. | Easy3 | GreedySimulation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Rock-Paper-Scissors ScoreGiven a player's rock-paper-scissors choices against several friends over multiple rounds, compute the actual score and the best possible score with foreknowledge each round. | Easy3 | SimulationGreedy+1 | No attempts yet | 1s | 128 MB | Judgeable |
| NoiseGiven two powers of ten with up to 100 digits and an operator, compute their sum or product using big-number arithmetic. | Easy3 | MathString+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Croatian AlphabetParse a string left to right, greedily matching multi-character Croatian letter codes (like c=, dz=, lj), and count total letters. | Easy3 | StringGreedy+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Three PartsSplit a short lowercase string into three contiguous non-empty parts, reverse each part, and find the split that yields the lexicographically smallest concatenation. | Easy3 | Brute forceString+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Secret EmailGiven an encrypted string, find matrix dimensions R<=C with R*C=N and largest R, then reverse a row-major-write column-major-read transposition to recover the original message. | Easy3 | MatrixString+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Lexicographically Smallest Crossword WordExtract all horizontal and vertical maximal letter sequences of length at least 2 from a grid and output the lexicographically smallest one. | Easy3 | StringImplementation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| IPv6Given a shortened IPv6 address with omitted leading zeros and possibly one '::' run, expand it into eight full 4-digit hex groups. | Easy3 | StringImplementation | No attempts yet | 1s | 128 MB | Judgeable |
| Rhyme PatternGiven verses of four lines, extract each line's last syllable from its final word and classify the rhyme pattern as perfect, even, cross, shell, or free. | Easy3 | StringImplementation | No attempts yet | 1s | 128 MB | Judgeable |
| Most Visited DomainsParse a list of URLs to extract each domain suffix and print the maximum visit count along with all domains that reach it, sorted alphabetically. | Easy3 | StringHash map+1 | No attempts yet | 1s | 128 MB | Judgeable |
| DECODEBuild a substitution cipher table from a key word placed at a given offset, then decode a given ciphertext using it. | Easy3 | StringSimulation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Reaux! Sham! Beaux!Parse rock-paper-scissors rounds given in multiple languages per player, tally wins, and print each game's score and winner. | Easy3 | StringHash map+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Bug KingRepeatedly remove all occurrences of the substring "BUG" from each input line, using a stack-like scan since removals can form new matches, until none remain. | Easy3 | StackString | No attempts yet | 1s | 128 MB | Judgeable |
| Character RecognitionRead multi-line text blocks separated by blank lines, count '#' as unrecognized characters, and print the recognition percentage formatted with rounding rules. | Easy3 | StringImplementation | No attempts yet | 1s | 128 MB | Judgeable |
| Adding Reversed NumbersReverse two given numbers, add them, then output the sum reversed with leading zeros dropped. | Easy3 | StringImplementation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Turing Arithmetic ExpressionsGiven up to nine large integers and an arithmetic expression using them, evaluate the expression under mod-10 addition and multiplication with normal precedence and print the result digit. | Easy3 | MathString+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Whitespace King: Aligning ColumnsReformat text lines so that words in each column line up to a width equal to the longest word in that column, with single spaces separating columns. | Easy3 | StringImplementation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| Alien Communication MasterclassGiven true bases and false bases, output a fixed-form product-of-factors equation that holds only for the true bases in that numeral system. | Easy3 | MathImplementation+1 | No attempts yet | 3s | 256 MB | Judgeable |
| Java vs C++Detect whether a name follows Java camelCase or C++ snake_case rules and convert it to the other style, or print an error if invalid. | Easy3 | StringImplementation | No attempts yet | 1s | 128 MB | Judgeable |
| Unreliable MessengersGiven a sequence of reversible string transformations and the final message, undo each transformation in reverse order to recover the original message. | Easy3 | StringSimulation+1 | No attempts yet | 1s | 128 MB | Judgeable |
| My Brother's DiaryFind the Caesar shift whose most frequent ciphertext letter maps to E, print the smallest valid shift and the decrypted text, or NOT POSSIBLE if several shifts work. | Easy3 | StringImplementation+2 | No attempts yet | 1s | 128 MB | Judgeable |
| CIVIC DILL MIXRead groups of valid Roman numerals, add each group, and print the sum and case number back in standard Roman form. | Easy3 | StringMath+1 | No attempts yet | 1s | 128 MB | Judgeable |
| WordsRead lines until a line with a single #, and output each line with the characters of every word reversed, keeping spaces fixed. | Easy3 | StringImplementation | No attempts yet | 1s | 128 MB | Judgeable |
| Memorable Phone NumbersNormalize each listed phone number to seven digits and report those appearing more than once, sorted, with their counts. | Easy3 | StringHash map+2 | No attempts yet | 1s | 128 MB | Judgeable |