Fast powers test
What is the fastest way to test if an int is a power of two?
Lots of 0's
How many zeros are on the end of n! ? Assume n is big. So n! is REALLY big.
What's wrong with...
How many combinations?
A TripAdvisor Rubick's Cube has owl heads on it, which can be misoriented. How many (times) MORE combinations are there of this cube vs. one that has blank stickers?