I applied online. I interviewed at Meta (Menlo Park, CA) in Jan 2018
Interview
I applied through linked for a specific team. Got the call from a recruiter. I had two interviews. One coding and one behavioral. In coding I was asked leetcode medium difficulty question. I was asked time and space complexity and to write the test case.
Interview questions [1]
Question 1
Given a map from digit to letters:
1 - 'ABC'
2 -'DEF'
..
Return all possible strings for any arbitrary number for example 9842 .
The process took 2 days. I interviewed at Meta in Jan 2010
Interview
For interns: 2 rounds of on-campus interviews. You need to answer at least 3 questions in the 2nd round. The interviewers are nice and supportive in general, and helpful if you need clarification of the problem. Both interviews are entirely technical. On average, you need to solve one question in 15 mins, and that includes coding on paper and testing with some of your own cases.