I met the CTO at a career fair, and interviewed with him the following day. It was a pretty standard tech skills interview- checking to make sure I knew what a hash map was, and a pretty basic coding task. He was really friendly and it was a pretty comfortable interview. I then waited a while, and had a phone interview, and then another phone screen a while after. The interviewer on the last phone call told me that my solution to the questions he asked was actually one of the better ones he'd seen, but then I never heard anything from them again.

Explain the idea of hash maps and hashing.