Code golfing

The goal of code golfing is to write the shortest possible program to implement certain algorithms or solve a problem.

Code golfing can be competed in any programming language you like, and you may wish to use a language that you are familiar with. However, we will also be playing with GolfScript to write really short programs.

This repository contains a bunch of challenges to try in the evening.

Setting up GolfScript

1. Head over to the GolfScript site and download the interpreter for it (it is a Ruby script)
2. Install Ruby if you haven't already
3. Create a simple example file gcd.gs

;'2706 410'
~{.@\%.}do;

4. Open a terminal and run ruby golfscript.rb gcd.gs (assuming the Ruby and code are in the

So how does GolfScript work?

Firstly, you might want to check out the GolfScript examples, the builtiin references and the quick reference.

The Euclidean algorithm calculated the greatest common denominator between two numbers a and b:

function gcd(a, b)
  while b != 0
    t := b
    b := a mod b
    a := t
  return a

Here's a quick reference for the symbols in the GCD program:

;           Pop and discard top item from stack (cleanup)
'2706 410'  Raw string with two numbers
~           Pops the string and evaluates it, pushes two numbers onto stack
{           New code block
  .         Duplicates the top item on the stack (t = b)
  @         Rotates the third element on the stack to the top (t, a, b)
  \         Swaps the top two items on the stack (t, b, a)
  %         Mod so stack is now (t, a mod b)
  .         Duplicates the top item on the stack, so it can be checked to 0
}
do          Pops the stack, and if non-zero then repeat code block (we want a)
;           Pop, because we want a (not b)

Challenges

These problems are quite simple, so I'd recommend starting with them for the code golfing.

• Project Euler 1 - Multiples of 3 and 5
• Project Euler 2 - Even Fibonacci numbers
• Printing Pascal's triangle

These challenges are a bit more complex, and you should therefore try them in a language you know better!

• A Brainfuck interpreter (or better, a compiler)

Bonus challenge: implement a your own language for code golfing.

I'll happily add any more suggestions, e.g. from the Programming Puzzles and Code Golf Stack Exchange or subreddit.