What I’ve learned: * I can’t formulate a max-flow or a min cost max-flow problem out of it. * I can’t prove it’s not possible. * I can’t prove it’s possible. * A first take at a greedy solution leaves four "holes" * With A*, a lot of pruning, and some heuristics, I’ve been able to get a close solution with 2 "holes"
A hole in a mapping is the inability to change some letter into some other letter by adding more punches.
Am I going to stop working on it?