Google Software Engineer, University Graduate interview questions

I was contacted by a recruiter one day after submitting my resume and then scheduled a phone interview with someone based in Mountain View three weeks later. But surprisingly, the interviewer didn't call me on the scheduled day itself. So I had to reschedule it to one week later. However, the person in charge of scheduling was on a sick leave so I had to reschedule it again. On my third interview, very unfortunately, the (same) interviewer didn't call me once again because of some urgent family issues. So I had my fourth interview scheduled, with a Sydney-based interviewer. This time it eventually worked out. I think the interviewer was very professional. I managed to solve two problems in 45mins but sadly, failed to be invited for the next round. Anyway, Google is my dream company. I will reapply in a year.