Wouldn't this fail (logic error) if s - y is less than -128 or greater than 127? Because sometimes the needed copmlement is not in the i8 range. So then the indexing would confuse it with another complement value that is inisde the i8 range. If so, it could be fixed by a simple bounds check on x and a continue if it is out of bounds.

Very nice use of iterators!! :)

Lmao what?

didn't read that width and height will be > 1 :D

Yeah, you're right. At some point this kumite changed into testing whether or not the number is even.

As for the power_of_two, I think that the first solution was the best one:
return n & ( n - 1 ) == 0

Am i mistaken or does this only check if the number is even and not odd, but does not check if it's a power of two? For example

power_of_two(6)
True

I guess the test cases only test odd numbers for the False test case and thus the test cases work fine.