I wanted to work on Advent of Code Day 4, so I clicked on the link above Day 3 thinking it's the next problem. I read through the problem to learn that I needed to code up a linear solver. Yes I did study math in college but that's a while back.
Inverting a 2x2 matrix wasn't hard, but I tried replicating the example given and always ended up with the wrong answer. It turns out that I calculated the determinant of the matrix, but did a multiply instead of a division.
I completed Part 1 and realized the problems weren't sorted in order - above Day 3 was actually Day 24!
Oh well.
For this problem I invested a bit more time writing a scanner. This way parsing the text needed to be done only once instead of multiple times when using `.split()` (even though from a performance perspective it probably doesn't move the needle).
What's quite nice is using Github Actions as a test runner. I previously did this when experimenting with ChatGPT to improve my code. The small change I did this time around was to use `ruff` instead of `black`, but no better reason besides that's what I kept seeing the cool kids use.