Meta Software Engineer interview questions

on campus at Menlo Park, which is called Facebook University Day. 45min technical interview, code on white board. After that we had a wonderful tour of Facebook Campus and had a lunch. The ice-cream was super good! After that, Facebook Engineers made presentations and lectures about how it feels to work at Facebook.

I applied at a campus recruiting event and got an email a few days letter about scheduling an interview on campus. It was a 45 min technical one on one interview. He asked me one straightforward question (see below). A few days after the interview, I got an email inviting me to their Menlo Park location for another interview on campus. I flew out there for University Day and really enjoyed the whole experience. The interview was 45 mins again and the interviewer asked me two questions (see below). I thought I answered the questions really well in O(n) but did not get an offer.