Going back and completing the old Advent of Code challenges. My goal for this one is to work on producing tidy Prolog solutions using any of the predicates from the standard SWI-Prolog library.
All solvers take a command line argument indicating which part to solve, and
read their input from stdin. For example, to run part 2 of the Day 1 solver with
the input in input.txt, type:
./01.pl 2 < input.txt