Meta Software Engineer - Internship interview questions

No behavioral questions. On campus interview 45 minutes. Two code challenges. One is check if a string is a number(all kinds of numbers), another one is about meeting rooms.

45 min phone interview. First few minutes were general introductions; what team the interviewer was in and what he was currently working on. Then moved directly into the coding question. Came up with possible solution pretty quick. After talking through all of it again, was asked to improve the runtime of one of the methods. Ended the interview with a few minutes for any additional questions.