Decided to use Rust on this one. Let's go!!
Thus far, the challenge for a particular day is divided into two parts. I've therefore decided to name the files as per the day and also the part.
The files are there named in this format. day<number><part>. Day numbers less than 10 are zero-padded. e.g.
day011.rs could be read as day01 for day 1 and 1.rs being part 1.