For the tenth year in a row, it's the time of the year to do Advent of Code again.
The solutions are written with the following goals, with the most important goal first:
- Speed. Where possible, use efficient algorithms for the problem. Solutions that take more than a second to run are treated with high suspicion. This need not be overdone; micro-optimisation is not necessary.
- Readability.
- Less is More. Whenever possible, write less code. Especially prefer not to duplicate code. This helps keeps solutions readable too.
All solutions are written in Ruby.
Features from 3.0.x will be used, with no regard for compatibility with past versions.
Enumerable#to_h with block is anticipated to be the most likely reason for incompatibility (will make it incompatible with 2.5).
In general, all solutions can be invoked in both of the following ways:
- Without command-line arguments, takes input on standard input.
- With command-line arguments, reads input from the named files (- indicates standard input).
Some may additionally support other ways:
- None yet
Favourite problems:
- None yet.
Interesting approaches:
- None yet.
- None yet.
Before I post my day N solution, the day N leaderboard must be full. No exceptions.
Waiting any longer than that seems generally not useful since at that time discussion starts on the subreddit anyway.
Solutions posted will be cleaned-up versions of code I use to get leaderboard times (if I even succeed in getting them), rather than the exact code used. This is because leaderboard-seeking code is written for programmer speed (whatever I can come up with in the heat of the moment). This often produces code that does not meet any of the goals of this repository (seen in the introductory paragraph).
The index lists all years/languages I've ever done (or will ever do).