Yes, that's exactly what it's for. The answer I hope for is that they don't care about the case of x==0, so that I can leave out the "x &&" part, leaving the no

Yes, that's exactly what it's for. The answer I hope for is that they don't care about the case of x==0, so that I can leave out the "x &&" part, leaving the noticeably simpler answer (x & x-1) == 0