Meta Software Developer interview questions

I was contacted by the Facebook recruiter saying I need to solve one of the puzzle from the Facebook puzzles to start the interview process. I had solved one problem and then recruiter scheduled my phone interview. The interview was good. The guy at the other end was nice and smart. The interview last for around 1 hr. It start by asking me about myself. He asked me about my choice between three platforms (linux kernel, MySql, JAVA script). I had chosen Mysql and he asked me why did I choose MySql. Other questions are described below. I got response from the recruiter that they would like to keep me on hold, as they are finding difficulty in judging with large number of candidates. I answered all questions correctly (I feel) except my written code (took around 10 to 15 mins) for the problem had one bug which he had noticed correctly and told me to resolve it. After resolving it he gave me the green signal. One of the big problem (I guess one of the main factor in the interview) I faced that as I am OK with English, I was finding difficulty in understanding his accent. So many times the interviewer had to repeat his questions. Lastly he asked me if I have any questions for them. I asked one question. This is how end my phone interview with Facebook.

An HR contacted me and said I should complete one of their three hardest puzzles. The puzzle was interesting, but the fact that I spent 2.5 days to do that (1 day was spent on submitting it in a correct way so that the puzzle robot accepts it), and it won't help when interviewing anywhere else, annoyed me. I then had a phone interview. The guy was very clever, which was nice. The questions were: what is the most exciting project you had, and white a function to multiply two arbitrarily large integers. I spent quite a while writing a recursive solution for the problem, made some mistakes during that, but fixed those purely by myself. The interviewer did not provide any feedback during the process when I described my "way of thinking" and the programming, so I even had to ask whether he was on the line. With phone interview, not feedback is a bit too harsh, imho. Then I was asked to write an iterative solution, and I completed it as well. I did not write the solutions easily, and my way of explaining was not perfectly clear and great, but I solved what I was asked. Then the HR contacted me saying they won't consider me anymore this year. I politely asked for feedback, but got the answer that there is nothing to share. Quite surprising for a social-oriented company.