In order to have all thing working, put in files under ./src/testdata
your input files.
zig run ./src/main.zig
If you want to check implementation with test
zig ./src/day01.zig
If you don't have a rust environment you can create as follow with different tools.
https://github.com/jetify-com/devbox
curl -fsSL https://get.jetify.com/devbox | bash
cd <here>
devbox install
devbox shell
which zig # installed using devbox + nix
eval "$(devbox generate direnv --print-envrc)"