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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...

As you might know, there were elections in Germany, and now the parties have to form a government coalition. Let's help them with it! A good coalition has the strict majority of seats (that is, mo...

Jelly has an atom called untruth, which when given indices, creates an array with 1s at those places: [2,4] → [0,1,0,1]. You are required to perform the inverse of this. Given a 2D boolean array, ...

Rules Using your language of choice, golf a quine. A quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output. No cheating -- ...

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. ...

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...

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 Ludic Numbers are a sequence that pops up when you apply the sieve of eratosthenes to the natural numbers, completely removing the numbers every iteration. Here is how they are generated: The...

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...

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 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 ...

Challenge Make a program that takes input of a string and abbreviate it. All letters of an abbreviation are capitalized, so keep that in mind. Whitespace, numbers and non-English characters ar...

Challenge Output the following text: A ABA ABCBA ABCDCBA ABCDEDCBA ...

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...

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 ...

Background A House of I I went on an adventure Grabbed resources and making deeds Like start to work on the materials To build the shelter I need It was a marvelous one At least in the eyes ...

Challenge Write as many functions, programs, or snippets of code, that result in 256. Your score is the number of separate solutions submitted in an answer. The challenge? The characters used in ...

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 ╔╦╗ ╠╬╣ ...

The task Given a positive integer as input, output tiled pyramids of this height. How? Let's say the inputted integer was n. From there, we output n lines of output, each having: A decreasing...

Given two strings, I define their product as follows: If any of the two strings is empty, the product is the empty string. If the second string consists of a single character, the result ...

The task is to generate the text of Lewis Caroll's Jabberwocky. The text, quoted from Wikipedia, is as follows (I've replaced a non-ASCII character with ASCII, otherwise it's direct copy&paste...

Credit This challenge is taken with permission from https://www.mysterytwisterc3.org/en/challenges/level-1/beaver-code Description The encryption method is as follows: The plaintext is divided ...

Definition $F_{n}\left(0\right)=0$ $F_{n}\left(1\right)=1$ $F_{n}\left(x\right)=n\cdot F_{n}\left(x-1\right)+F_{n}\left(x-2\right)$ For example: $F_{1}=\left[0,1,1,2,3,5,8,13,21,34,55,89...\ri...

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; ! ...

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...

Given an array of numbers, output the length of the longest increasing (not necessarily contiguous) subsequence. It is guaranteed that there are no duplicates in the array. For example, if the inpu...

You have an army of size $n$ that you need to split up to fight $k$ battles simultaneously against an opposing army $A$. In each battle, the army with the most troops present wins - no one wins a t...

Given a musical key, output its number and letter on the Camelot Wheel (shown below). Input A musical key as a string, as shown on the wheel. The words "Sharp" and "Flat" may be replaced with s...

A Juggler sequence is a sequence that begins with a positive integer $a_0$ and each subsequent term is calculated as: $$a_{k+1} = \begin{cases} \left \lfloor a_k ^ \frac 1 2 \right \rfloor, &...

CGCC Sandbox, Codidact Sandbox Given three positive integers as input, animate an ascii-art polygonal loading symbol on the screen. Intro Using the first input $n$, Take one the following regul...

SE Sandbox Link, Codidact Sandbox Link Inspired by this video. Given a positive integer, draw its Cistercian representation as ascii art. The Challenge Cistercian numerals are a decimal-based...

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...

Using your languages of choice, golf a quine - a non-empty program taking no input and only outputting its source. Here, the win condition is your quine working in the most languages. It should be...

Abundant numbers are numbers which are less than their proper divisor sum. For example $18$ is abundant as $1 + 2 + 3 + 6 + 9 = 21 > 18$ Deficient numbers are numbers which are greater than the...

Heavily based on this closed challenge from SE. Description A Sumac sequence starts with two non-zero integers $t_1$ and $t_2.$ The next term, $t_3 = t_1 - t_2$ More generally, $t_n = t_{n-2} ...

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...

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...

Challenge Given an array consisting of positive integers and 0s, return it with 0s acting like backspaces. Leading backspaces do nothing, and more backspaces than elements also does nothing. Cre...

Challenge You will be given a string and an ascii art as input. The string must be placed above the ascii art, and centered based on its longest line. The text BOTTOM TEXT must be placed below...

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...

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...

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...

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) ...

Note: This challenge was underspecified and bad, and as such I would not encourage answering it in the future. Challenge You will be given a single 2D boolean array $M$. You may take its dimensi...

Print or return this exact text: 0 0 0 0 1 0 0 1 1 0 0 1 2 1 0 ...

Define a cool number as a number whose proper divisors (all except for the number itself) have an integral mean. Define a really cool number as a number whose divisors (including itself) are all co...

Challenge Given a date with day, month and year, calculate how old a person born on that day would be today. Input can be in any reasonable format(params, array, date object). Input will never b...

The task is to take a decimal integer as input and print the corresponding Roman numeral with capital letters. The program must handle all positive integer numbers between 1 and 1000. Input can be...

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