Each year since 2015, Advent of Code is a series of 25 puzzles in December.
The puzzles are somewhat interesting if you like programming. You get a tour of classic programming problems and solving methods. It's always nice to learn and practice.
Python is a nice language to use because it's easy and fast to write scripts with it. I made it in the top 100 twice thanks to it (there's a global leaderboard on the website).
I used Zig to solve the 2020 edition. Zig is supposed to be "like C but better while staying simple".
The language is still immature (latest version is 0.7.1) but it already works quite well. There is one documentation page but it only covers the basis. To understand how to use the stdlib, the best method is to look directly at its source code. Each file has some unit tests that also serve as examples.
My solutions are available on my GitHub if you want to consult them for some reason: link