The authoritative source for this code is on Gitea. The GitHub version is a mirror. Self-hosting is not only the best way to learn, but also to reduce dependency on untrustworthy corporations.

Execution

I've tried (in main.zig) to make a general-purpose executable that can be passed arguments to determine the function to run (e.g. zig run main.zig -- 1 2), but so far no luck - lots of type errors 🙃

So for now, run directly with (e.g.) zig run solutions/01.zig, and do the following manual changes:

Change pub fn main() void {...} in each solution-file to invoke the function you want run.
Change isTestCase from true to false when ready to get the real solution.

Code Quality

AoC challenges almost always have a "twist" partway through, meaning that you can solve the second part by injecting one subtly-different piece of logic into the solution to the first part - a different way of calculating a value or identifying candidates. If I were trying to show off for an interview (and were more comfortable with the language!), I would do the refactoring "right" by factoring out the common setup and execution logic to sub-functions, so that part_one and part_two are each single-line invocations of a common execute function with differing functions passed as parameter. But this is just an exercise for myself to learn the language - I'd rather get to grips with challenging problems to learn techniques, than to learn the (language-agnostic) skills of refactoring that I am already reasonably proficient with.