Puzzle 43 - symmetrical solution


#1

This doesn’t optimize for part count, but is aesthetically interesting in that the board is symmetrical, and takes advantage of the symmetry of XOR. If the bits are not in the “correct” state for capture, the current bit is inverted and a ball of the opposite color is released, which inverts the sense of the output. It’s a basic kind of recursion perhaps?

https://www.lodev.org/jstumble/?board=rlelreerelfbaflgxgreerbaleerilfrlfexfelrf

Starting with the blue lever solves the problem as written, and starting with the red lever simply switches the meaning of red and blue in the output.