Advent of Code submissions

My submissions for the Advent of Code challenge. Details here:

https://adventofcode.com

All submissions are in Ruby.

• The 2018 / 2019 folders have the versions of the code exactly as I submitted them — written as fast as possible with no thought to code style or performance at all.
• The 2018-golf folder has golfed versions of some of the challenges from that year. I didn't get very far with the golfing.