An interesting challenge is to try to generate this puzzle, or one like it, once you know the answer. Given any existing grid, you can implement a "step" funct

An interesting challenge is to try to generate this puzzle, or one like it, once you know the answer. Given any existing grid, you can implement a "step" function in code that generates the next grid describing it. You'll always find a cycle by stepping over and over (the numbers can never get too high, so the space is finite, so you'll always converge to a cycle rather than diverging). The goal, then, is to find a cycle of length 2 (or, better yet, a fixed point that maps to itself). I just coded this up to try it out, and one simple starting point gave a cycle of length 27. I tried randomly generating starting points and I can generate a 3-cycle but haven't hit any 2-cycles yet. So maybe there's another trick to get the configuration from the puzzle. Edit: nevermind, I misinterpreted the puzzle. All letters in the grid count, so "FOUR F'S" has two Fs and an S. Accounting for that, a randomized approach quickly finds a 2-cycle. But I guess it's interesting that a relatively minor tweak like that has a different outcome.