Advent of Code 2020
See https://adventofcode.com/2020/
The core logic for each day is in a separate file, but everything can be run from the main program.
My solutions are in Kotlin, because I like the language and want to practice it more.
There are unit tests which sometimes go beyond the strict requirements of the AoC specifications or inputs. For example, on day 1 it handles the case of duplicate values appearing in the input, although no such values actually appeared in the supplied file.
I like to try to find a generally functional-style solution, even if there may be a simpler procedural approach because, again, it's good practice. I hope that things are reasonably readable. I aim to keep functions short and to name things clearly (well, clearly to me ...).
As I've gone on I've also decided to stick to a self-imposed constraint
of making everything purely functional with no mutable state -- there
shouldn't be a single var in sight ... That has definitely stretched
me on occasions and meant that it's taken me rather longer to solve
some things than it might otherwise have done.
I'm also experimenting a bit with different Kotlin idioms, so there might be different styles from day-to-day. For example, on day 3 I was going for a recursive solution and on day 4 I made everything an extension function, for no very profound reason.