Questions tagged [code-golf]

Code-golf is a competition to solve a particular problem in the fewest bytes of source code. If you want to score by characters instead of bytes, please state this explicitly in the challenge. If source code length is not the primary scoring criterion, consider using another tag instead.

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104
votes
66answers
26k views

I'm a palindrome. Are you?

There have been a couple of previous attempts to ask this question, but neither conforms to modern standards on this site. Per discussion on Meta, I'm reposting it in a way that allows for fair ...
104
votes
39answers
11k views

A simple TCP server

Write a program or function that listens for incoming TCP traffic on port N. It offers a simple service: it calculates sum of IP address fields of incoming connection and returns. Program or function ...
103
votes
16answers
5k views

Simulate the Universe!

One nice property of a Turing-complete language is that it can be used to write any program, up to and including the simulation of the entire Universe. Your job is to do exactly that: write a program ...
101
votes
16answers
19k views

Possibly quit your job with a polyglot

Despite your protest, you have been put to work by your boss on a program that takes a single unsigned integer as input and prints the string "prime" if that integer is prime and "not prime" if it isn'...
100
votes
25answers
15k views

Print a Negative of your Code

Consider a square of printable ASCII characters (code points 0x20 to 0x7E) for side length N, like the following (here, N = 6): ...
100
votes
31answers
16k views

If a program terminates and there is no one to see it, does it halt?

It's time to face the truth: We will not be here forever, but at least we can write a program that will outlive the human race even if it struggles till the end of time. Your task is to write a ...
100
votes
14answers
5k views

Seven Slash Display

Write a program that takes in a non-empty string of the digits 0 through 9 and prints how they would be shown on a seven-segment display using slashes (/, ...
99
votes
47answers
25k views

I copied my password to the clipboard! Can you delete it?

Following the best security practices, I keep a plain text file with my passwords on my hard drive. In fact, I just copied and pasted one of them to access my PPCG account. In a lucid moment, I ...
99
votes
9answers
6k views

Write an interpreter for 99

99 (pronounced "ninety-nine") is a brand new Esoteric programming language (not to be confused with 99, note the italics). Your task in this challenge is to write an interpreter for 99 that is as ...
98
votes
12answers
9k views

Proving that a Russian cryptographic standard is too structured

The aim of this challenge is to find an impossibly short implementation of the following function p, in the langage of your choosing. Here is C code implementing it ...
98
votes
14answers
10k views

Has my milk expired?

Aww, man, this expiry date doesn't write the months with letters! I can't tell if it's expiring on March 10th or October 3rd... Wait, no, never mind, the year says 2012. (alley-oops half-used brick of ...
97
votes
236answers
15k views

Output with the same length as the code

In this challenge, you should write a program or function which takes no input and prints or returns a string with the same number of bytes as the program itself. There are a few rules: You may only ...
97
votes
3answers
3k views

Sprocket Science: Animating a Chain Drive System

The goal of this challenge is to produce an animation of a chain drive system, comprised of a set of sprocket gears connected together by a chain. General Requirements Your program will be given a ...
95
votes
54answers
13k views

Make a “Ceeeeeeee” program

Once I wrote a JavaScript program that would take as input a string and a character and would remove all characters except for the first one and the character given as input, one by one. For example, ...
95
votes
28answers
6k views

Does the code terminate?

This is a code golf challenge I thought of with a mathematical bent. The challenge is to write the shortest code possible such that it is an open question whether or not the code terminates. An ...
94
votes
109answers
15k views

Will it halt? (Cops)

This is the cops' thread. The robbers' thread is here. Your challenge is to make a program that runs forever without halting1, unless it gets a particular input or inputs2. If it receives that input, ...
93
votes
105answers
14k views

Code Golf Christmas Edition: How to print out a Christmas tree of height N

Given a number N, how can I print out a Christmas tree of height N using the least number of code characters? ...
93
votes
14answers
19k views

I am passive aggressive and want to insult my boss without him finding out

It's been a rough few months at work and I feel like I just want to scream right to my boss' face. I am, however, not one to directly confront people I have a problem with. I also don't want to lose ...
92
votes
20answers
14k views

Where's the 0xBEEF?

This challenge was inspired by this Wendy's commercial from 1984. Illustration by T S Rogers Your task is to find a hexadecimal 0xBEEF on a binary bun. The 'beef' consists of the following pattern: ...
92
votes
34answers
6k views

Would this string work as string?

Write a program that takes a single line string that you can assume will only contain the characters /\_‾. (That's forward and backward slash, underline and ...
92
votes
41answers
27k views

Implement the Thanos sorting algorithm

The sorting algorithm goes like this: While the list is not sorted, snap half of all items (remove them from the list). Continue until the list is sorted or only one item remains (which is sorted by ...
91
votes
35answers
16k views

Mandelbrot image in every language

I always used a Mandelbrot image as the 'graphical' version of Hello World in any graphical application I got my hands on. Now it's your guys' turn. Language must be capable of graphical output or ...
91
votes
48answers
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 ...
91
votes
46answers
6k views

5 Favorite Letters

The challenge is actually extremely simple. Pick 5 distinct letters (you can just pick the 5 that allow you the shortest code if you like) and output them to the console. However, the twist is that ...
90
votes
45answers
27k views

Fifty Shades of Grey

Boys and girls are excited to see Fifty Shades of Grey on the silver screen, we just want to code without being bothered, so here's a challenge to pick our brain. You have to: Print on the screen ...
90
votes
23answers
11k views

Programming a Pristine World

Let's define a pristine program as a program that does not have any errors itself but will error if you modify it by removing any contiguous substring of N characters, where ...
90
votes
38answers
11k views

Tips for Golfing in ECMAScript 6 and above

This is similar to other "Tips for golfing in <...>" but specifically targeting the newer features in JavaScript brought up in ECMAScript 6 and above. JavaScript inherently is a very verbose ...
90
votes
14answers
6k views

The Colors in Our Stars

Write a program that takes in a string or text file whose first line has the form width height and each subsequent line has the form ...
88
votes
9answers
5k views

Golf an Advent Calendar

It's that time of year when many of us get our advent calendars! If you are unfamiliar with an advent calendar, these are special calendars used to count down advent in anticipation of Christmas. In ...
87
votes
267answers
17k views

Simple cat program

One of the most common standard tasks (especially when showcasing esoteric programming languages) is to implement a "cat program": read all of STDIN and print it to STDOUT. While this is named after ...
87
votes
38answers
21k views

Tips for golfing in Java

Are there any useful shortcuts that can be used in Java? As shown below, import already adds at least 17 characters to a program. ...
87
votes
79answers
22k views

It took me a lot of time to make this, pls like. (YouTube Comments #1)

Hold up..... this isn't trolling. Background These days on YouTube, comment sections are littered with such patterns: ...
87
votes
14answers
8k views

[CHRISTMAS THEME DISCLAIMER HERE]

Note to mods, if the title doesn't do justice, change it to whatever, I thought it was funny. You're tasked with hanging up the lights for this Christmas season, and your family has decided that for ...
87
votes
26answers
6k views

The Hungry Mouse

Sixteen piles of cheese are put on a 4x4 square. They're labeled from \$1\$ to \$16\$. The smallest pile is \$1\$ and the biggest one is \$16\$. The Hungry Mouse is so hungry that it always goes ...
86
votes
265answers
15k views

Create output twice the length of the code

The Challenge Write a complete program that writes twice as many bytes to standard output as the length of the program. Rules The program must write ASCII characters to the standard output. The ...
86
votes
278answers
22k 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 ...
85
votes
67answers
14k views

Print your code backwards - reverse quine

Write a program that prints its own source code out backwards, in other words an eniuq. Scoring: +50 if you use pull data from the Internet. +25 if you read your own source code. +1 point per ...
85
votes
60answers
20k views

Shut down the computer!

Challenge: In the programming language of your choice, shut down the machine that your code was executed on. Rules No shutting down by resource exhaustion (e.g.: forkbomb to force shutdown) You are ...
85
votes
103answers
11k views

N(e(s(t))) a string

To "function nest" a string, you must: Treat the first character as a function, and the following characters as the arguments to that function. For example, if the input string was ...
85
votes
133answers
11k views

Determine whether strings are anagrams

Challenge Given two strings, work out if they both have exactly the same characters in them. Example Input word, wrdo This returns true because they are the ...
85
votes
28answers
4k views

Vertically collapse text

Say I have text like this (each word on one line, with no spaces) Programming Puzzles & Code Golf That makes no sense! It totally defies the laws of physics. ...
84
votes
13answers
7k views

Z̡̬a̧̯̔l̆̓g̛̘̟o̡ generator

Write a program or function that transforms an input string into Zalgo text. For example, for an input string Zalgo, a possible output might look like: ...
83
votes
103answers
16k views

Shortest code to produce non-deterministic output

You need to produce output that is non-deterministic. In this case, this will be defined to mean that the output will not always be the same result. Rules: A pseudo-random number generator that ...
83
votes
40answers
13k views

What my dog really hears

My dog is called Rex. Every time I scold him, he seems not very impressed and the only times I see him react is when I pronounce his name. If I say ...
83
votes
6answers
4k views

3D ASCII Block Building

Challenge Write a program that takes an 11x11 array of integers, and constructs a 3D ASCII block building, where each value in the array represents the height of a column of blocks at the coordinates ...
82
votes
45answers
16k views

Sleep for 1000 years

Some sleep commands implement a delay of an integer number of seconds. However, 232 seconds is only about 100 years. Bug! What if you need a larger delay? Make a ...
82
votes
25answers
7k views

Bake a slice of Pi

Write a program or function that prints or outputs this exact text (consisting of 142 characters): ...
82
votes
43answers
7k views

2048-like array shift

Assume we want to shift an array like it is done in the 2048 game: if we have two equal consecutive elements in array, merge them into twice the value element. Shift must return a new array, where ...
82
votes
28answers
6k views

You're on a 8 day streak!

Duolingo, the language learning app, has a lot of things going for it, but there is one major issue that drives me crazy. It tells me how many days in a row I've used the app with a message like You'...
81
votes
35answers
9k views

Tips for golfing in <all languages>

The aim of this post is to gather all the golfing tips that can be easily applied to <all languages> rather than a specific one. Only post answers that its ...