I'd love to see the formulation for this problem written out in proper form that can be fed to a solver like MiniZinc or CPLEX or whatever type of solver can handle it.
It looks like Hakan K (has a super cool website where he solves all kinds of optimization problems for fun) was able to solve it using the Picat language in a very small amount of code with a solution (not sure if optimal):
For those of us that are not experts, how is this sort of problem generally classified? I've seen others on here say classical planning, but I wasn't sure if that is correct.