Microsoft Software Engineer - Internship interview questions

First, on campus interview. Easy string reversal and behavioral questions. Next, onsite. Fairly straightforward technical question, not sure why not given offer. Also asked question about system design, not prepared.

Two rounds, one on campus and one onsite. My onsite was a series of three interviews, each with a tech question and other behavioral/resume questions. The on-campus dude was a bit scary because he didn't say much, but all the onsite people were very friendly and easy to talk to.