It was an on-campus interview at CMU. I attended one of the university's job fairs and received an email about the interview within a week.

Facebook also held a candidate reception in a plaza near the CMU campus. We had the opportunity to meet our interviewers in advance and ask any questions.

As for the interview itself, I was asked several general questions about my projects (nothing too special, really).

The coding question was a standard regular expression matching problem, which you can find on LeetCode.

Since I am still in my Master's program, I haven't yet reached that level on LeetCode.

I did solve the question in the end after the interviewer gave me some hints, but I don't think I did a very good job.