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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...

Challenge Given a string, e.g. Hello, do the following: Mirror it: Hello -> HelloolleH and create a right triangle using it as the sides: H ee l l l l o...

Given a positive integer as input, indicate which base from 2 to 16 gives the most holes in the representation of the input in that base. The digits used are 0123456789ABCDEF. Note that these incl...

Introduction The classic "Hello, World" challenge. What more can I say? Rules Program takes no input. Program outputs Hello, World! with an optional trailing newline. No other output is accep...

Given a grid of numbers, mark the concentric areas around nonzero elements (beacons) decreasing from the value of the beacon till 1. For example, here are some grids with a single beacon: Size 1:...

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...

A chequer board (also spelt "checker board" in some places) is an 8 by 8 grid of squares alternating between 2 colours. Check whether a provided pattern could be a region of a chequer board. The c...

Challenge Given an array in any suitable format, create a frequency table for it. i.e: Pair each unique element with the number of times it appears in the array. You can return the frequency tabl...

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 ...

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...

Multiply complex numbers. 2 space-seperated ones will be input, as follows: (update: you can replace i with j or some other symbol if needed) a+bi -a+bi a-bi -a-bi where a and b are integers ...

Given an positive integer $n$, return the least positive integer $k$ such that the $k$th partial sum of the harmonic series is greater than or equal to $n$. For example, if $n = 2$, then $k = 4$, b...

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 ...

Get ready for a comparatively dry question - this is intended to be one of the "the"s of the code-golfing dictionary. Create a program which inputs a base 10 non-negative whole number (without lea...

Task Given an IP address as a string, find its IP address class. For reference, here is a table: Class Leadingbits Numberof networks Addressesper network Total addressesin class Start...

Description From the Esolangs wiki, In Fractran, a program consists of a finite list of positive, rational numbers. The input to a program is a positive integer n. The list is then searched ...

Create a program P1 which takes as input a base 10 number N1 (the numbers for the variables are important). Given N1, P1 will print a program P2. P2 will take as input a base 10 number N2 and outpu...

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...

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 ...

Introduction The Pell(no, not Bell) Numbers are a simple, Fibonacci-like sequence, defined by the following relation: $P_n=\begin{cases}0&\mbox{if }n=0;\\1&\mbox{if }n=1;\\2P_{n-1}+P_{n-2...

Challenge It's a bootstrapping challenge this time! Write a full program that, once run, writes the source code of another program that in turn, once run, writes the source code for another progra...

In Google Docs, the word count tool looks like this: Pages would not make sense, but your goal is to implement every other count. Definitions Words are strings of text separated by any amount ...

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...

A rewrite of this SE question with a simpler input format and guidelines. Challenge Deadfish uses a single accumulator, on which all commands are to be performed. It has the following commands: ...

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...

In this simple challenge, create a short program that takes 2 ints as input, output them, swap their places, then output them again. Those 2 integers can't be the same number. The program with the ...

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...

Given a non-ragged array (an array where all sub-arrays at a particular level have the same length) of non-negative integers, answer its shape, that is, the length along every dimension. You may as...

Challenge Make a program that takes input of an integer that's $n > 1$ and print out a staircase using a specific character for stair basing (hashes (#) for demonstration; you can use spaces,...

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...

Task Print the following: ABDFHJLNPRTVXZ CABDFHJLNPRTVX ECABDFHJLNPRTV GECABDFHJLNPRT IGECABDFHJLNPR KIGECABDFHJLNP MKIGECABDFHJLN OMKIGECABDFHJL QOMKIGECABDFHJ SQOMKIGECABDFH USQOMKIGE...

Challenge Given a list of n numbers and x, compute $a + bx^1 + cx^{2} + ... + zx^{n-1}$, where a is the first value in the list, b is the second, etc. n is at most 256 and at least 0. The input va...

Definitions A binary tree is either a null (leaf), or an object (node). A node contains a value (non-negative integer) and two pointers (left and right) to two separate binary trees. A binary tre...

Given an integer n, output the smallest prime such that the difference between it and the next prime is at least n. For example, if n=5, you would output 23, since the next prime is 29, and 29-23&...

Given a list of strings(and optionally, their length) as input, weave the strings together. Intro Your goal is to mimic the WV operator in Pip. Take a list of strings and alternate between their ...

Challenge Given two strings a and b, return the shortest string s so that s starts with a and ends with b. (Inspired by https://chat.stackexchange.com/transcript/message/57816868#57816868 ) Exam...

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...

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...

Natural to set (set meaning an unordered collection with no duplicates, though answers may use and output lists instead) Recently I was brainstorming what a language with only (arbitrarily nested...

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...

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...

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...

The task Output the first 100 elements of the infamous FizzBuzz sequence. How? The FizzBuzz sequence is the sequence of decimal integers from 1 to 100 inclusive, but: If the integer is divisi...

[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...

Your challenge today is to golf a program to interpret something Turing-complete. You may use any Turing-complete system for this so long as it is not the source language of the challenge - even a...

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: ...

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...

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...

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