I paused a bit before reading about the possible solutions, and actually thought of the (prime number) solution the interviewer came up with. I realise that th

I paused a bit before reading about the possible solutions, and actually thought of the (prime number) solution the interviewer came up with. I realise that this is a bit of redundant post .. but, as a person who isn't a brilliant coder I surprised myself. But then again, after reading the comments here - I think maybe I just have an obtuse way of thinking about things.