> With the Aho-Corasick implementation you can just map the string -> {ordered list of matches} -> numbers associated with the match, and then you've got a little vec of digits you can grab the first and last entries of.
My solution was to shove it through `Itertools::minmax_by_key(|m| m.start()).into_option()`, which returns the lowest and highest matches (or a duplicate of a single match). Then to map to digits I actually ordered the patterns differently: I went 1, 2, 3, ..., one, two, three, ...
That way:
- for part 1 I could slice out the first 9 elements and it works uniformly
- mapping a "digit" to an actual digit is taking the index (match.as_pattern().as_usize()) modulo 9 to shift the textual versions to the numerical, then add one.
0/zero is not a valid digit so you can just ignore it, although you could always include it, use mod 10, and not increment the result, so same diff.
