I got an interview from a recruiter since I had participated in one of Google's summer programs. I was scheduled for two interviews, one after the other, on the same day. My interviewers were very friendly and down-to-earth.

Given an array of unsorted integers, arrange them such that a < b > c < d > e, and so on.

I noted Python as my language of choice and was thus asked a lot about it, including libraries I had not used before. So, whatever language you pick, make sure you're an expert in it!