2022 - Day 7

[romellem]

Hardest one yet! Decided to do what I normally do for these: OOP.

• Created a File and Dir class, and just for fun, a Filesystem class that mostly handles parsing of the input, and some sugar for iterating over the file tree.
• Parsing is pretty basic: startsWith checks for what kind of line we are looking at, and regex to extract name and size values.
• Determining size of directories is done with recursion: both Files and Dirs have a size() method. When a Dir's size() is call, we say its the size of its contents sizes added up. Its contents can either be files or dirs, so if it is a dir, that's where we see the recursion.
• Finally, for part two, I add an argument to the size() method to ignore an item's size. If the thing we are looking at is what we should ignore, we immediately return 0. So for dirs, it doesn't recursive through its tree.