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The problem Someone has created an encoding format for square bit matrices, however they have found it isn't perfect! One encoding may not decode to exactly one matrix, or it may not even be possi...
Given a sequence of lower case letters, sort them into order of height. Heights The heights of letters are dependent on font, so for this challenge the height order to be used is as defined below...
Background Inspired by this challenge that is also a mathematical English translator. Challenge Write a program that translates a mathematical expression using English with the following specifi...
Connect opposite corners of a rectangle of characters without putting 4 characters in a row. Input Two numbers, W and H, representing the width and height of the rectangle Each number will be ...
Challenge What do computers understand? That's right, binary. All files are turned into binary digits when you run them, but what if I suggest giving you an int then turn it into it's binary value...
Introduction What is the Caesar shift cipher (ROT$n$)? It's basically a cipher sequence that changes a letter's value from the number chosen. If we use ROT1 on "games", we get "hbnft". The basic i...
An integer is called square-free if it is not a multiple of a perfect square other than 1. For example, 42 is square-free, but 44 is not because it is a multiple of the perfect square 4 = 2². Your...
Inspired by this challenge. If anyone has any suggestions for a song title I could use for the challenge title then please leave a comment. Definition We define f(x) for a given integer as the su...
Challenge Given an integer n>=4 as input create an ASCII art "prison door"* measuring n-1 characters wide and n characters high, using the symbols from the example below. Example ╔╦╗ ╠╬╣ ...
Given a non-negative integer up to $999\,999\,999$, write it in English. The input number can be in any form other than English (though you'll typically want to use the native integer type of your...
Rational numbers in decimal representation can have an infinite periodic part. One common way to write this down is to repeat the periodic digits and then add three dots. Numbers without those thre...
This challenge is based on the i. verb from J. A range grid is basically a range of m × n numbers fit into a rectangular grid with m rows and n columns. A 2×3 range grid would be: 0 1 2 3 4 5 ...
Looping counter Create an infinite loop that outputs lines of asterisks, with each line containing one more asterisk. Instead of the asterisk, any printable, non-whitespace character can be used. ...
Challenge Given a list of integers >= 0 , check if all of them are equal. Tests [1,1,1,1,1] -> true [0,1,1,6,7] -> false [1] -> true [] -> undefined(you do n...
Challenge Create a program that takes input of a string and outputs an integer using the following calculation system: The string can only contain +, -, *, /, ^, ! (or a different character; ! ...
Challenge A Niven number is a positive integer which is divisible by the sum of its digits. For example, 81 -> 8+1=9 -> 81%9=0. Your task is to find the first n Niven numbers, given n. Te...
Imagine you have only one byte (8 bits) to store a value, but need to store values from $0$ to $4032$. Impossible, until you are also told that an error of 1/64 of the exact value does not matter. ...
Challenge idea taken from: Eliseo D'Annunzio Task Provide code that evaluates to 0.5 numerically, i.e. the output must be recognized by your chosen language as a numeric value (Number, float, dou...
Background Check out this video on the Collatz conjecture, also known as A006577. If you don't know what this is, we're given an equation of $3x + 1$, and it is applied this way: If $x$ is odd...
ROBBERS' THREAD A famous cops-and-robbers challenge whose source shall remain unnamed is brought to Codidact. You are a cop. You should write a program in a "famous" (has an English Wikipedia/Eso...
Disclaimer This challenge also exists in CGCC, but if you want to compete here (too), then hop in! Challenge Recreate "99 Bottles of Beer on the Wall", using the least bytes possible. Lyrics: ...
Make the Server Fault logo using the following criteria: The boxes' measurements: There are 3 columns of 5 boxes, with long ones at the left where the rest are regular. The following measure...
About Negabinary Negabinary means base negative two (-2). That is, the $n$th place value is determined by $(-2)^n$. Negabinary numbers can be evaluated just like any other base system. For exampl...
Challenge Given the roots of a polynomial (that is, the $x$ values where the polynomial evaluates to zero), as an array of real numbers, return the polynomial's coefficients. That is, given real ...
Background While we do have a "Hello, World!" challenge, we still don't have one regarding input. So let's do one! Challenge Create a program that takes an input (not as a function argument) the...
Inspired by this Rosetta Code article. Introduction Balanced Ternary is a method of representing integers using -1, 0 and 1 in base 3. Decimal 11 = (1 * 32) + (1 * 31) + (−1 * 30) = [1,1,-1] or ...
Many programming languages have the concept of keywords, special syntax items that are not just identifiers reserved by some library, but words reserved by the language itself. The challenge is to...
The task is to create a program which displays a golf score as text. It takes 2 numbers as input, separated by space or new line: The first number is the par of the specific hole. The second nu...
Challenge Given a list of unique colour names as input, sort them in the order that they first appear in Joseph's Amazing Technicolour Dreamcoat. Example Input: green, blue, red, brown Outpu...
Create a program that gets all perfect squares starting from 0 or 1 without using any methods of multiplication (repetitive addition) and exponentiation (repetitive multiplication). Output them for...
Goldbach's Conjecture states that every even whole number greater than 2 is the sum of 2 prime numbers. Your task is to return those 2 prime numbers, given an even whole number as input. There are ...
Challenge This is a simple randomness challenge: Given a non-negative integer $n$, and positive integer $m$, simulate rolling and summing the results of $n$ fair dice, each of which have $m$ sides...
[Rule 110] is a Turing complete cellular automaton. It is defined as follows: Take as initial value a sequence of symbols that's infinite to both sides, which consists only of two different symbol...
Challenge Make a program that takes input of 3 non-negative integers: a result and 2 other values that once calculated results to the 3rd value. The program must figure out how to get the 2 fir...
Originally from Somewhere Else. I thought I'd continue making more drawing challenges here now that I discovered it. Make the Stack Overflow logo using the following criteria: The tray: ...
The Rules In this game, each round, every player faces off against every other player in a round robin format. In each match, players pick 3 positive integers that sum to 360. Let's say player 1 p...
Challenge Write a program that prints its reversed self. For example, if your code is foo() Then it'll output: )(oof Make sure that the quine is a valid one, as defined here: No cheatin...
Challenge We all know and love the generic sort function, right? However, it only sorts based off one criterion - what if we want more? That's where you come in. Your task is to sort an array bas...
COPS THREAD A famous cops-and-robbers challenge whose source shall remain unnamed is brought to Codidact. You are a robber. Your goal is to find answers on this link which haven't been cracked an...
Two words are anagrams of each other if the letters of one can be reordered to spell the other; e.g. ADOBE and ABODE are anagrams. An alternate way of describing it is that both words contain the s...
Idea shamelessly stolen from caird and rak1507 Shuffle a subset of a list of unique, positive integers with uniform randomness, given the indices of that subset. For example, given the list $[A, B...
Challenge A catalogue type challenge that simply asks: Given an integer n (where n>=0) as input return a truthy value if n is a perfect square or a falsey value if not. Rules You may take...
Challenge Cause the currently running program to receive the SIGSEGV signal (on Linux or other *nix systems) as fast as possible. What it does with the signal doesn't matter as long as it receives...
Run-length encoding is a simple compression technique which compresses sequences of repeating identical bytes. The encoding rules for this task are as follows: Any sequence of $n$ identical bytes...
In this challenge, add 2 integers, but if both the integers are 2, output 5. Shortest code in each language wins! Example ungolfed program in Python 3.x def add(x, y): if x == 2 and y == 2: ...
Task I often need to find the factorial of a number or the sum of all numbers up to a number when cheating on math tests. To help me with this, your task is to write $F$, a generalized version of ...
Write the shortest program that takes no input and outputs a Sudoku solution. For reference, a Sudoku solution is a 9x9 grid of digits where each column, each row and each of the nine 3x3 grids th...
Description APL trains are a series of functions, that get applied to an argument in this way: (f g) x = f g x (f g h) x = (f x) g (h x) (a b c d e f) x = (a (b c (d e f))) x = a (b x) c (d x) ...
Given a string and a non-negative integer $n$, output a new string in which each character is repeated $n$ times. Test cases: "abc", 1 -> "abc" "Hello", 0 -> "" "double", 2 -> "ddo...
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