All Questions

Filter by
Sorted by
Tagged with
1190 votes
6 answers
286k views

Build a working game of Tetris in Conway's Game of Life

Here is a theoretical question - one that doesn't afford an easy answer in any case, not even the trivial one. In Conway's Game of Life, there exist constructs such as the metapixel which allow the ...
user avatar
  • 33.8k
607 votes
309 answers
231k views

Produce the number 2014 without any numbers in your source code

Note to challenge writers as per meta consensus: This question was well-received when it was posted, but challenges like this, asking answerers to Do X without using Y are likely to be poorly received....
user avatar
  • 33.8k
546 votes
239 answers
128k views

Showcase of Languages

Notes This thread is open and unlocked only because the community decided to make an exception. Please do not use this question as evidence that you can ask similar questions here. Please do not ...
537 votes
1 answer
181k views

Build a digital clock in Conway's Game of Life

Your task is to build a Game of Life simulation representing a digital clock, which satisfies the following properties: The clock displays the hours and minutes in decimal (e.g. ...
user avatar
  • 33.8k
503 votes
932 answers
174k views

"Hello, World!"

So... uh... this is a bit embarrassing. But we don't have a plain "Hello, World!" challenge yet (despite having 35 variants tagged with hello-world, and counting). While this is not the most ...
user avatar
460 votes
50 answers
167k views

Images with all colors

Similar to the images on allrgb.com, make images where each pixel is a unique color (no color is used twice and no color is missing). Give a program that generates such an image, along with a ...
user avatar
424 votes
21 answers
144k views

Build a Compiler Bomb

Introduction You're probably familiar with zip bombs, XML bombs, etc. Put simply, they are (relatively) small files which produce enormous output when interpreted by naïve software. The challenge ...
user avatar
  • 8,351
391 votes
156 answers
272k views

Write a program that makes 2 + 2 = 5 [closed]

Write a program that seemingly adds the numbers 2 and 2 and outputs 5. This is an underhanded contest. Your program cannot output any errors. Watch out for memory holes! Input is optional. ...
user avatar
  • 11.2k
390 votes
46 answers
57k views

Covfefify a string

In this challenge, you must take a string matching the regex ^[a-zA-Z]+$ or whatever is reasonable (you don't have to consider uppercase or lowercase letters if you ...
user avatar
384 votes
36 answers
70k views

American Gothic in the palette of Mona Lisa: Rearrange the pixels

You are given two true color images, the Source and the Palette. They do not necessarily have the same dimensions but it is guaranteed that their areas are the same, i.e. they have the same number of ...
user avatar
383 votes
110 answers
88k views

Most creative way to display 42

Douglas Adams was born on March 11, 1952, and died when he was just 49. In honor of this wonderful writer, I challenge you to display 42 in the most creative way possible. You could print it in the ...
user avatar
  • 3,072
368 votes
1 answer
115k views

Regex that only matches itself

There are some pretty cool challenges out there involving regex (Self-matching regex, Regex validating regex) This may well be impossible, but is there a regex that will ONLY match itself? NOTE, ...
user avatar
350 votes
7 answers
45k views

Upgoat or Downgoat?

Given an image of a goat, your program should best try to identify whether the goat is upside down, or not. Examples These are examples of what the input may be. Not actual inputs Input: Output: <...
user avatar
  • 28.4k
326 votes
55 answers
109k views

Tweetable Mathematical Art [closed]

Integer math can generate amazing patterns when laid out over a grid. Even the most basic functions can yield stunningly elaborate designs! Your challenge Write 3 Tweetable (meaning 140 characters ...
user avatar
320 votes
168 answers
121k views

Tips for golfing in Python

What general tips do you have for golfing in Python? I'm looking for ideas which can be applied to code-golf problems and which are also at least somewhat specific to Python (e.g. "remove comments" is ...
user avatar
  • 12.3k
318 votes
24 answers
44k views

Write Moby Dick, approximately

Here is a 1.2Mb ASCII text file containing the text of Herman Melville's Moby-Dick; or, The Whale. Your task is to write a program or function (or class, etc. -- see below) which will be given this ...
user avatar
  • 7,182
307 votes
7 answers
34k views

Draw with your CPU

I have come across an article where students used network traffic to draw their university on the country's IPv6 graph. [image] Your goal is simple to tell, but hard to implement. Draw the text MAIL (...
user avatar
  • 4,214
292 votes
34 answers
214k views

High throughput Fizz Buzz

Fizz Buzz is a common challenge given during interviews. The challenge goes something like this: Write a program that prints the numbers from 1 to n. If a number is divisible by 3, write Fizz instead....
user avatar
291 votes
377 answers
121k views

Add a language to a polyglot

This is an answer-chaining challenge in which each answer builds on the previous answer. I recommend sorting the thread by "oldest" in order to be sure about the order in which the posts are ...
user avatar
285 votes
73 answers
77k views

We're no strangers to code golf, you know the rules, and so do I

Write the shortest program that prints the entire lyrics of "Never Gonna Give You Up" by Rick Astley. Rules: Must output the lyrics exactly as they appear in the above pastebin*. Here's the raw dump:...
user avatar
  • 4,420
278 votes
141 answers
499k views

I need a program where the user inputs an array of doubles and the program outputs the array sorted

Note: This question was severely edited since I first posted it here. The rules were moved to here, read them before posting any answer to understand the purpose of this. This was the first question ...
user avatar
278 votes
33 answers
90k views

Make it look like I'm working

Often, I find myself running a script or query that will take a significant amount of time to run. I can leave that script open and enjoy some guilt-free procrastination. Now, what if I could write a ...
user avatar
  • 2,633
259 votes
133 answers
35k views

Without using numbers, get the highest salary you can. But don't exaggerate!

As I'm applying for some jobs whose job advert doesn't state the salary, I imagined a particularly evil interviewer that would give the candidate the possibility to decide their own salary ...by "...
user avatar
  • 2,611
254 votes
37 answers
48k views

Paint Starry Night, objectively, in 1kB of code

Note: a 1000 point bounty is still available for this challenge, which I will create and award if anyone takes the top score without using built-in compression. Below is a ...
user avatar
  • 7,182
247 votes
81 answers
80k views

Code that will only execute once

Goal The goal of this challenge is to write code that will execute once and only once. This means basically that it damages the program, script, or environment in some way. If rebooting the system ...
user avatar
  • 2,797
245 votes
56 answers
54k views

Survival Game - Create Your Wolf

The Board The Board is a two dimensional array of cells. Cells are populated by Animals. Every day, all Animals on the Board simultaneously make one move. If two or more Animals move to the same cell, ...
user avatar
  • 6,316
234 votes
28 answers
24k views

DISARM THE B.O.M.B.!

You have been hired for your tech knowledge as a Secret Agent's sidekick to ensure that the good guy can get his job done and the world can be saved. This is your last mission before retiring with a ...
user avatar
  • 4,077
233 votes
415 answers
58k views

Golf you a quine for great good!

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 -- that means ...
user avatar
  • 2,607
233 votes
184 answers
37k views

Evolution of "Hello World!"

This contest is officially over, the winner is jimmy23013. Congratulations! The challenge is to make a program that prints Hello World! to stdout. The catch is that ...
user avatar
231 votes
109 answers
42k views

Print every character your program doesn't have

Your task is to build a program (using only printable ASCII characters and/or tabs and newlines) that prints out exactly the characters in the printable ASCII space (...
user avatar
  • 33.8k
228 votes
336 answers
58k views

Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
user avatar
  • 207k
225 votes
62 answers
19k views

No A, just CAPS LOCK

What happens when the CapsLock key on your keyboard doesn't have a notch in it? "This hPPENS." The goal of this program is to consistently emulate keyboard misses where each A press is replaced with ...
user avatar
  • 1,801
210 votes
88 answers
38k views

Make your language unusable

Try to write some code in your language and make it not satisfying our criteria of being a programming language any more. A language satisfies our criteria (simplified version for this challenge) of ...
user avatar
  • 36.1k
198 votes
212 answers
44k views

The Programming Language Quiz

Congratulations to Dennis who won both the cops' and the robbers' challenge! Calvin's Hobbies has already delivered on his promise and wrote this challenge for Dennis for winning the robbers' ...
user avatar
195 votes
120 answers
26k views

I'm not the language you're looking for!

Isn't it annoying when you find a piece of code and you don't know what language it was written in? This challenge attempts to somewhat solve this. Challenge You will have to write a program that ...
user avatar
  • 28.2k
193 votes
80 answers
26k views

What? No error? [closed]

Your task is simple. Write a program that should obviously produce an error on first glance either when compiled or run, but either doesn't or produces some other unrelated error. This is a popularity ...
user avatar
  • 3,580
192 votes
61 answers
30k views

Mathematics is fact. Programming is not

In mathematics an exclamation mark ! often means factorial and it comes after the argument. In programming an exclamation mark ! ...
user avatar
189 votes
161 answers
19k views

What is the smallest positive base 10 integer that can be printed by a program shorter (in characters) than itself?

I think the question as above is clear, but just in case: Write a full program (not just a function) which prints a positive base 10 integer, optionally followed by a single newline. Qualifying ...
user avatar
  • 1,909
184 votes
382 answers
66k views

1, 2, Fizz, 4, Buzz

Introduction In our recent effort to collect catalogues of shortest solutions for standard programming exercises, here is PPCG's first ever vanilla FizzBuzz challenge. If you wish to see other ...
user avatar
  • 22.8k
182 votes
29 answers
23k 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: ...
user avatar
181 votes
50 answers
39k views

Trolling the troll [closed]

A troll has captured you and is forcing you to write malware (defined as a program that damages the computer that runs it). The troll can read and understand code, but is not so good at spotting bugs. ...
user avatar
173 votes
99 answers
40k views

Programming Languages Through The Years

In this challenge, users will take turns completeing three fairly simple coding tasks in programming languages that are allowed to be progressively older. The first answer must use a programming ...
user avatar
170 votes
36 answers
24k views

Write program in your favorite language in another language [closed]

The determined Real Programmer can write Fortran programs in any language. from Real Programmers Don't Use Pascal Your task is to write program in your programming language of choice, but you are ...
user avatar
168 votes
70 answers
24k views

How high can you count?

Challenge: Your task is to write as many programs / functions / snippets as you can, where each one outputs / prints / returns an integer. The first program must output the integer ...
user avatar
168 votes
8 answers
35k views

Draw an Image as a Voronoi Map

Credits to Calvin's Hobbies for nudging my challenge idea in the right direction. Consider a set of points in the plane, which we will call sites, and associate a colour with each site. Now you can ...
user avatar
167 votes
463 answers
33k views

Implement a Truth-Machine

A truth-machine (credits goes to this guy for coming up with it) is a very simple program designed to demonstrate the I/O and control flow of a language. Here's what a truth-machine does: Gets a ...
user avatar
167 votes
91 answers
60k views

Tips for golfing in JavaScript

What general tips do you have for golfing in JavaScript? I'm looking for ideas that can be applied to code golf problems in general that are at least somewhat specific to JavaScript (e.g. "remove ...
user avatar
  • 5,982
167 votes
163 answers
56k views

Don't google "google"

We all know that if you google the word "google" it will break the internet. Your task is to create a function that accepts one string and returns its length, in the fewest possible Unicode ...
user avatar
  • 4,517
165 votes
128 answers
32k views

Trick or Treat polyglot

Since Halloween is coming up I thought I might start a fun little code golf challenge! The challenge is quite simple. You have to write a program that outputs either ...
user avatar
  • 1,531
165 votes
5 answers
17k views

Hyperprogramming: N+N, N×N, N^N all in one

Write a program that takes in a number N from 1 to 9 inclusive. In its native form your program should output N+N. E.g. output 2 if N is ...
user avatar

15 30 50 per page
1
2 3 4 5
265