# Questions tagged [code-golf]

Code-golf is a competition to solve a particular problem in the fewest bytes of source code.

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### Shortest terminating program whose output size exceeds Graham's number

Write the shortest possible program (length measured in bytes) satisfying the following requirements: no input output is to stdout execution eventually terminates total number of output bytes exceeds ...
8k views

### Print/Output the L-phabet

Inspired by George Gibson's Print a Tabula Recta. You are to print/output this exact text: ...
8k views

### Reverse Polish notation

You must evaluate a string written in Reverse Polish notation and output the result. The program must accept an input and return the output. For programming languages that do not have functions to ...
7k views

### Test a number for narcissism

A Narcissistic Number is a number which is the sum of its own digits, each raised to the power of the number of digits. For example, take 153 (3 digits): 13 + 53 + 33 = 1 + 125 + 27 = 153 1634: ...
6k views

### Greatest Common Divisor

Your task is to compute the greatest common divisor (GCD) of two given integers in as few bytes of code as possible. You may write a program or function, taking input and returning output via any of ...
6k views

### Catalan Numbers

The Catalan numbers (OEIS) are a sequence of natural numbers often appearing in combinatorics. The nth Catalan number is the number of Dyck words (balanced strings of parenthesis or brackets such as ...
6k views

### Is string X a subsequence of string Y?

Given strings X and Y, determine whether X is a subsequence of Y. The empty string is regarded as a subsequence of every string. (E.g., '' and ...
2k views

### Tips for golfing in Julia

What general tips do you have for golfing in Julia? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Julia (e.g. "remove comments" is ...
793 views

### Tips for golfing in Prolog

What general tips do you have for golfing in Prolog? I am looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Prolog (e.g. one letter ...
1k views

### All your bijective base are belong to us

Background A bijective base b numeration, where b is a positive integer, is a bijective positional notation that makes use of b symbols with associated values of 1 to b. Unlike its non-bijective ...
2k views

### Spell out the Revu'a

Actually not inspired neither by Atbash Self Palindromes nor by Generalized Gematria Calculator. Given a string s of length n, output the Revu'a sequence, which is the first character of s, the first ...
630 views

### Determine the position of a non-negative number in the infinite spiral

Definition The infinite spiral used in this question has 0 on the position (0,0), and continues like this: ...
2k views

### Words from periodic table of elements [closed]

Back when I was a freshman in highschool taking chemistry, I'd look at the periodic table of elements and spell dirty words out with the number of the elements (HeCK would be 2619, 2-6-19). I was ...
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### Case Permutation

Who needs to compare things case insensitively when you're able to generate every permutation of uppercase and lowercase? No one! That's the answer. No one does. Your task is to achieve this feat; ...
27k views

### Unscramble the Source Code

Note: This challenge is now closed to new cop submissions. This is to ensure that no one can post submissions that only remain uncracked because there aren't enough robbers interested in the challenge ...
21k views

### Do you want to code a snowman?

Here is a simple ASCII art snowman: _===_ (.,.) ( : ) ( : ) Let's make him some friends. This will be the general pattern for our ASCII art snowpeople: ...
7k views

### Bake a slice of Pi

Write a program or function that prints or outputs this exact text (consisting of 142 characters): ...
4k views

### Self-Interpreting Interpreter

Based on a comment by George Edison to this question, write the smallest self-interpreting interpreter. You may use the language of your choosing. Empty languages do not count. Your program must be ...
2k views

### Tips for golfing in vim

I've recently realized how vim works great for golfing, especially for kolmogorov-complexity. Also, according to meta vim is a perfectly acceptable 'programming language' at least, for the scope of ...
11k views

### Enlarge ASCII art

In this challenge, you must take multiline ASCII art as input, such as: ...
5k views

### Implement hyperexponentiation/tetration without the use of '^'

The Challenge Implement tetration (aka Power Tower or Hyperexponentiation) with the least amount of characters. The Conditions Don't use the 'power' operator or its equivalents (such as ...
2k views

You must write a program that evaluates a string that would be entered into an advanced calculator. The program must accept input using stdin and output the correct answer. For languages that do no ...
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### Sį“į“ŹŹ Cį“į“ź± Cį“É“į“ į“Źį“į“Ź

Portable Spec. IÉ“ź±į“ÉŖŹį“į“ ŹŹ @ConorO'Brien's į“ź±į“ŹÉ“į“į“į“. AŹź±į“ į“Źį“É“į“ź± į“į“ @Dį“į“Źį“É“į“Ź ź°į“Ź ź±Źį“į“”ÉŖÉ“É¢ į“į“ į“Źį“ į“xÉŖź±į“į“É“į“į“ į“ź° Ē« į“É“į“ x. Sį“į“ŹŹ ...
7k views

### Notcalc (Calculate the wrong answer)

Goal: Given two natural numbers (integers from 0 to infinity), output a number that is not the sum of those numbers, but is a natural number. Example solutions (TI-Basic): ...
3k views

### Boustrophedonise

Related but very different. A boustrophedon is a text where every other line of writing is flipped or reversed, with reversed letters. In this challenge, we will just reverse every other line, but ...
9k views

### Will Jimmy fall off his platform?

Backstory Meet my friend Jimmy: /o\ Jimmy is a little character who likes to stand on platforms. Here's Jimmy safely standing on a platform: ...
4k views

### Generate a Kolakoski sequence [duplicate]

Definition1 A Kolakoski sequence is a self-describing infinite sequence {kn} of alternating blocks of 1's and 2's, given by the following rules: k0 = 1 kn = the length of the (n+1)'th ...
2k views

### Tips for golfing in Lua

What general tips do you have for golfing in Lua? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to Lua (e.g. "remove comments" is not ...
6k views

### Display number of occurrences for every character in an input string

The code should take a string as input from keyboard: The definition of insanity is quoting the same phrase again and again and not expect despair. The output ...
6k views

### N-dimensional N^N array filled with N

In: Enough memory and a positive integer N Out: N-dimensional N^N array filled with N, where N^N means N terms of N-by-N-by-N-by... Examples: 1: [1] ...
7k views

### Print the N-bonacci sequence

This isn't very widely known, but what we call the Fibonacci sequence, AKA 1, 1, 2, 3, 5, 8, 13, 21, 34... is actually called the Duonacci sequence. This is ...
3k views

### Write a Polyquine

A polyquine is both quine and polyglot.1 You are to write a quine which is valid in at least two different languages. This is code golf, so the shortest answer (in bytes) wins. 1 I made that up. Or ...
3k views

### Are you in the biggest room?

Introduction You have recently accepted a job offer at a Pretty Good Software Company. You're pretty content with the size of your office, but do you have the biggest office? Its kinda hard to tell ...
2k views

### The Coin Problem

Background The official currency of the imaginary nation of Golfenistan is the foo, and there are only three kinds of coins in circulation: 3 foos, 7 foos and 8 foos. One can see that it's not ...
2k views

### Calculate Ļ with quadratic convergence

Write a function or complete program that takes a positive number n and performs n steps of an iterative algorithm for ...
6k views

### Balanced Ternary Converter

Credits for the challenge idea go to @AndrewPiliser. His original proposal in the sandbox was abandoned and since he has not been active here for several months, I have taken over the challenge. ...
7k views

### Minecraft Mirrored

This is Calvin. Just trying to get 20 rep so this user can chat in the PPCG Minecraft Server chatroom. Write a program or function that takes in a positive integer. If the integer is even (2, 4, 6, ....
3k views

### Code-Golf: Permutations

Write a function that takes as input a set of integers (can be a list, array or any other container with distinct numbers), and outputs the list of all its permutations. Python (95 chars): ...
3k views

### Find the occurrences of a character in an input string

Challenge Write a program that, given a string x which is 10 characters long and a character y, outputs the number of times ...
1k views

### Golf me an ASCII Alphabet

Don't you find that reading simple text isn't appealing enough? Try our ...
1k views

### Polynomial Interpolation

Write a program that performs Polynomial Interpolation using true arbitrary precision rational numbers. The input looks like this: f(1) = 2/3 f(2) = 4/5 f(3) = 6/7 ... You may assume that there's ...
2k views

### Give me the Gray Code list of bit width n

The Gray Code is a sequence of binary numbers of bitwidth n where successive numbers differ only in one bit (see example output). Reference Example input: ...
9k views

### Golf a number bigger than TREE(3)

The function TREE(k) gives the length of the longest sequence of trees T1, T2, ... where each vertex is labelled with one of k colours, the tree Ti has at most i vertices, and no tree is a minor of ...
5k views

### Check if words are isomorphs

Two words are isomorphs if they have the same pattern of letter repetitions. For example, both ESTATE and DUELED have pattern <...
10k views

### Display random colored pixels

I've always liked screens full of randomly colored pixels. They're interesting to look at and the programs that draw them are fun to watch. The challenge Fill your screen, or a graphical window, ...
6k views

### Text compression and decompression ā “Nevermore.”

With the recent discussion about the use of compression tools in code golf, I thought it would be a nice challenge to write your own text compressor and decompressor. Challenge: Write two programs: ...
13k views

### In Honor of Adam West

Adam West passed away, and I'd like to honor his memory here on PPCG, though I doubt he knew of our existence. While there are many, many different things that this man is known for, none are more ...
17k views

### Outputting ordinal numbers (1st, 2nd, 3rd)

I would like to generate (as a return result of a function, or simply as the output of a program) the ordinal suffix of a positive integer concatenated to the number. Samples: ...
24k views

### Print a 10 by 10 grid of asterisks

Background This is a standard textbook example to demonstrate for loops. This is one of the first programs I learned when I started learning programming ~10 years ago. Task You are to print this ...