I just completed "Hoof It" - Day 10 - Advent of Code 2024 using Common Lisp! This one wasn't even hard compared to day 9!
https://adventofcode.com/2024/day/10
https://github.com/argentcorvid/AoC-2024/blob/main/day10.lisp
I re-wrote my solution to use an iterative Depth-First Search using DO*, then re-wrote that into a generalized version that can be used with a helper function.
https://github.com/argentcorvid/AoC-2024/blob/d10-iter/day10.lisp
@argentcorvid Very nice loop. I always forget about :with