Meta Software Engineering Internship interview questions

I submitted my application online and got an email from a recruiter a couple weeks later. I attended a social event Facebook held at my university and got to know the interviewers. The following week I had an in person interview at my university's campus. I spoke with one interviewer and wrote code on a white board. A couple weeks after I had another technical interview over video chat.

I had an on campus interview with a current software engineer. He first asked me to talk about some of the contents of my resume, and then asked me to elaborate on a recent project I worked on that I liked. He then asked me a few coding questions. Both went off of the same principle of trying to implement a method to process a certain type of regular expression. I coded on a whiteboard, and my interviewer gave feedback as I went along. At the end, he asked how I might optimize the method I wrote.