Sure, give someone a problem slightly harder than fizz buzz just to make sure they aren't a complete fraud. But the difference between someone who can solve an

Sure, give someone a problem slightly harder than fizz buzz just to make sure they aren't a complete fraud. But the difference between someone who can solve an easy whiteboarding problem and a hard one is merely the fact that they practiced for months doing it. It is unlikely that solving the hard problem is much of a signal other then that.