I disagree on it being "overthinking". I just did replacement without really thinking. Saw that it failed on the "eightwo" case since "two" got replaced first, so just replaced "two" with "two2two" instead, then passed it through solver for part1. To me that's simpler and more naive than correctly writing a search or backwards-forwards regex :)

My solution in Kotlin https://github.com/kolonialno/adventofcode/commit/686cbebb07...