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Challenges

Code challenges of all types. For questions about golfing, bowling, etc, use Q&A. For questions about this community, use Meta. To get feedback on a challenge before posting it, use Sandbox.

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92%
+23 −0
"Hello, World!"

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...

58 answers  ·  posted 3y ago by anna328p‭  ·  last activity 1y ago by __blackjack__‭

88%
+13 −0
Output 256 in many different ways

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 ...

12 answers  ·  posted 3y ago by dzaima‭  ·  last activity 2y ago by snail_‭

87%
+12 −0
Evaluate a single variable polynomial equation

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...

20 answers  ·  posted 3y ago by moony‭  ·  last activity 2y ago by south‭

87%
+12 −0
Cumulative Counts

Challenge Given an array of numbers return the cumulative count of each item. This is the number of times an item has occurred so far. Examples [1,1,2,2,2,1,1,1,3,3] -> [1,2,1,2,3,3,4,5,1,2]...

19 answers  ·  posted 3y ago by rak1507‭  ·  last activity 8mo ago by WheatWizard‭

87%
+12 −0
Partial Sums of Harmonic Series

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...

11 answers  ·  posted 3y ago by Quintec‭  ·  last activity 1y ago by south‭

87%
+12 −0
Print the Great Numeric Pyramid

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

5 answers  ·  posted 3y ago by Sisyphus‭  ·  last activity 3y ago by Marshall Lochbaum‭

86%
+11 −0
Weave Strings Together

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 ...

13 answers  ·  posted 3y ago by Razetime‭  ·  last activity 2y ago by radarek‭

86%
+11 −0
Reverse an ASCII string

Your goal is to reverse an ascii string. Given a (optionally newline or null terminated) input, output your input in reverse order, optionally followed by a newline. Terminate afterward. Function...

32 answers  ·  posted 3y ago by moony‭  ·  last activity 7mo ago by qwr‭

86%
+11 −0
Merge two strings

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...

8 answers  ·  posted 3y ago by rak1507‭  ·  last activity 2y ago by radarek‭

86%
+11 −0
Can you give me half?

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...

23 answers  ·  posted 2y ago by Razetime‭  ·  last activity 7mo ago by RubenVerg‭

85%
+10 −0
Create an Alphabet Diamond

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

11 answers  ·  posted 3y ago by dzaima‭  ·  last activity 2y ago by General Sebast1an‭

85%
+10 −0
It's Hip to be Square

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...

20 answers  ·  posted 2y ago by Shaggy‭  ·  last activity 2y ago by Zakk‭

85%
+10 −0
Are All Elements Equal?

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...

16 answers  ·  posted 2y ago by Razetime‭  ·  last activity 1y ago by torres‭

84%
+9 −0
Length of a Sumac Sequence

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} ...

9 answers  ·  posted 3y ago by Razetime‭  ·  edited 2y ago by General Sebast1an‭

84%
+9 −0
1, 2, Fizz, 4, Buzz!

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...

20 answers  ·  posted 3y ago by Dion‭  ·  last activity 2y ago by celtschk‭

84%
+9 −0
Obligatory Quine Challenge

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 -- ...

9 answers  ·  posted 3y ago by ATaco‭  ·  last activity 2y ago by General Sebast1an‭

84%
+9 −0
Coat of Many Colours

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...

6 answers  ·  posted 2y ago by Shaggy‭  ·  last activity 2y ago by radarek‭

84%
+9 −0
Looping counter

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. ...

19 answers  ·  posted 2y ago by celtschk‭  ·  last activity 6mo ago by H_H‭

83%
+8 −0
Solve Goldbach's Conjecture

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 ...

10 answers  ·  posted 3y ago by Quintec‭  ·  last activity 1y ago by torres‭

83%
+8 −0
Integer to Roman numeral

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...

3 answers  ·  posted 3y ago by Lundin‭  ·  last activity 3y ago by Lundin‭

83%
+8 −0
Compute the determinant

Challenge A simple challenge: Given a two-dimensional matrix (an array of arrays) of real numbers, compute the determinant. The determinant of a matrix is a mathematical construct used in many ap...

9 answers  ·  posted 2y ago by Moshi‭  ·  last activity 11mo ago by aspen138‭

83%
+8 −0
Golf a FRACTRAN interpreter

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 ...

8 answers  ·  posted 3y ago by Razetime‭  ·  last activity 1y ago by torres‭

81%
+7 −0
Make my number a set

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...

10 answers  ·  posted 3y ago by Wezl‭  ·  last activity 2y ago by radarek‭

81%
+7 −0
Backspace an array

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...

6 answers  ·  posted 2y ago by rak1507‭  ·  last activity 2y ago by Shaggy‭

81%
+7 −0
Evaluation order of an APL n-train

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) ...

7 answers  ·  posted 2y ago by rak1507‭  ·  last activity 2y ago by Shaggy‭

81%
+7 −0
Word Set Square

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...

11 answers  ·  posted 3y ago by Razetime‭  ·  last activity 1y ago by Shaggy‭

81%
+7 −0
Word Count Tool

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 ...

9 answers  ·  posted 2y ago by Quintec‭  ·  last activity 1y ago by torres‭

81%
+7 −0
Evens or Odds - you know this one

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...

16 answers  ·  posted 2y ago by AndrewTheCodegolfer‭  ·  last activity 1y ago by Olin Lathrop‭

81%
+7 −0
Reduce over the range [1..n]

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 ...

14 answers  ·  posted 2y ago by user‭  ·  last activity 1y ago by gifti‭

81%
+7 −0
Collatz conjecture; Count the tries to reach $1$

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...

15 answers  ·  posted 2y ago by General Sebast1an‭  ·  last activity 1y ago by torres‭

81%
+7 −0
Bytes to Segfault

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...

10 answers  ·  posted 3y ago by moony‭  ·  last activity 2y ago by radarek‭

81%
+7 −0
Truthify an array

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, ...

10 answers  ·  posted 3y ago by Razetime‭  ·  last activity 2y ago by General Sebast1an‭

81%
+7 −0
Roll n fair dice

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...

10 answers  ·  posted 2y ago by Moshi‭  ·  last activity 8mo ago by RubenVerg‭

81%
+7 −0
In The Jailhouse Now

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 ╔╦╗ ╠╬╣ ...

6 answers  ·  posted 2y ago by Shaggy‭  ·  last activity 2y ago by snail_‭

81%
+7 −0
Efficient censorship

You are a low-level censor working for the Ministry of Media Accuracy. Part of your job is to make sure that certain words don't appear in publications. Every morning you get a fresh stack of next...

4 answers  ·  posted 8mo ago by WheatWizard‭  ·  last activity 8mo ago by Shaggy‭

81%
+7 −0
Find n Niven Numbers

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...

7 answers  ·  posted 1y ago by Razetime‭  ·  last activity 1y ago by Shaggy‭

81%
+7 −0
Determine whether an integer is square-free

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...

13 answers  ·  posted 2y ago by celtschk‭  ·  last activity 1y ago by Shaggy‭

81%
+7 −0
Operation "Find The Operator"

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...

5 answers  ·  posted 2y ago by General Sebast1an‭  ·  last activity 2y ago by radarek‭

80%
+6 −0
Golf golf challenge

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...

5 answers  ·  posted 2y ago by Lundin‭  ·  last activity 2y ago by radarek‭

80%
+6 −0
Keyword golfing

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...

6 answers  ·  posted 2y ago by Lundin‭  ·  last activity 7mo ago by H_H‭

80%
+6 −0
Digit Sum Integer Sequence (working title)

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...

6 answers  ·  posted 2y ago by Shaggy‭  ·  last activity 5mo ago by RubenVerg‭

80%
+6 −0
Versatile self-printer

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...

1 answer  ·  posted 2y ago by AndrewTheCodegolfer‭  ·  last activity 2y ago by General Sebast1an‭

80%
+6 −0
Shape of an array

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...

6 answers  ·  posted 3y ago by Adám‭  ·  last activity 2y ago by south‭

80%
+6 −0
Juggler sequences

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, &...

9 answers  ·  posted 3y ago by caird coinheringaahing‭  ·  last activity 2y ago by Shaggy‭

80%
+6 −0
Beaver Code Decryption

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 ...

6 answers  ·  posted 3y ago by rak1507‭  ·  last activity 2y ago by Shaggy‭

80%
+6 −0
Write a Deadfish Interpreter

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: ...

8 answers  ·  posted 3y ago by Razetime‭  ·  last activity 2y ago by Zakk‭

80%
+6 −0
Is it a near-anagram?

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...

5 answers  ·  posted 3y ago by snail_‭  ·  edited 2y ago by General Sebast1an‭

77%
+5 −0
Guess the language! (Cops' Thread)

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...

16 answers  ·  posted 2y ago by AndrewTheCodegolfer‭  ·  last activity 2y ago by Shaggy‭

77%
+5 −0
99 Shortened Bottles of Beer

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: ...

13 answers  ·  posted 2y ago by General Sebast1an‭  ·  last activity 2y ago by General Sebast1an‭

77%
+5 −0
Repeat the characters

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...

14 answers  ·  posted 2y ago by celtschk‭  ·  last activity 2y ago by south‭