I was really surprised how efficient numpy arrays were at finding all combinations of the pieces. The backtracking is not using recursion, but instead a stack.

I was really surprised how efficient numpy arrays were at finding all combinations of the pieces. The backtracking is not using recursion, but instead a stack. This makes it more verbose to code and read, but easier to understand. I would like to make this notebook more interactive with ipywidgets and Unicode characters, so stay tuned ;)