There were a number of separate interviews with separate developers throughout the day, including a lunch-time, non-counting interview.

The questions were all about puzzles that you could easily look up (I had seen them all before in various books). Only one interviewer, at the end of the day in the last five minutes, even bothered to quiz me about my unique skills – a specialty that I was told Google was looking for and why I had chosen to accept the interview in the first place.

I went through the puzzles, writing my answers using brute force solutions rather than jumping to conclusions. This wasn't only because I felt it was fair, but also because I began to see the whole day as a waste of my time, as it became apparent they were more interested in playing games than testing my skills.

Actual puzzles are in the Cracking the Coding Interview book.

Based on NDA, I cannot say which ones, though.