[Natsu]

Oh, I did it by hand (and I was checking all the balls). I just missed one of the +4s somehow.

I wonder how efficient people can make this. I've envisioned all kinds of test cases that crank up the branching factor, require that you find solutions even if you have to trade away white balls for them and other such things.

Just because he made them positive integers doesn't mean that there are no ways to punish solutions that won't scale or those that don't always find optimal solutions.