Meta Software Engineer interview questions

An internal recruiter contacted me out of the blue by Linkedin and email. We scheduled a phone call. Talked about my experience and education and then about available positions at Facebook. He then invited me to come onsite for a short screening interview first. I requested a couple of weeks to prepare for the interview. He was perfectly ok with that and even sent me some links to preparation materials. Instead of a phone screen, I had a short 1:1 interview for 45 minutes onsite. Mostly coding on whiteboard and a little time set aside for questions about the company. A week after that, four 1:1 interviews. Two coding interviews. One "manager" interview: mostly talking about past projects and future ambitions. One system design interview - you basically have to describe how you would design a given system without going into too much detail. Received a call from recruiter next day. He said that I will have to come for one more interview. So a week after I had another series of two interviews, one coding and one manager. I received an offer two days after the last interview. During the whole process, the company was very flexible about scheduling interviews. Everything happens really fast if you want it, or you can take your time to prepare. Recruiter was very nice and supportive, as were people at FB in general. Some interviewers did not talk much and some were more willing to discuss, but all were very polite. Coding questions involve basic data structures like trees, combinatorial problems and sometimes a relatively simple dynamic programming problem. They are not too hard but you have to do them quickly and explain everything clearly. Understanding of Big-O is a must!