Meta Software Engineer,/Co op interview questions

I applied via the Facebook University site in mid-October. In mid-November, I received an email (which was automatically sent to my spam folder) that Facebook would like to move forward with an interview. I sent an updated resume, the responses to a short questionnaire, and had a first round interview scheduled for mid-December. The first round interview was straightforward. About two minutes past the designated time, I received a call from a Palo Alto phone number. I had a nice, easy to understand interviewer who asked me to write a function which, given a tree node, printed all routes to the leaves. I then was asked about space and algorithmic complexity. Since I finished this problem quickly, she gave a second: create a function which given a two dimensional array prints the diagonals. In other words, if given [[1,2,3],[4,5,6]], the function would print 1 2 4 3 5 6. I then had a few minutes to ask questions about the company. I was told to expect to hear from my recruiter within five days. Fifty minutes later, I got an excited email from my recruiter telling me I had been selected for a second round interview. It was scheduled for the day after my last finals. Again, about two minutes after the agreed upon time, I received a call from another Palo Alto phone number. Another very kind, easy to understand lady. We talked about my resume for about ten minutes (note this was the first person to discuss my experience) and then jumped into the coding problem. About a week later, I got an email from my recruiter informing me that Facebook would no longer be considering me for an opportunity.