My resume was submitted by an employee. I received a call from the recruiter the next day. She was nice and explained the process, then scheduled me for a phone interview within the same week. She was kind enough to provide some interview tips, so I had the chance to review some topics. I believe Facebook recruiters are entirely on your side.

The phone interviewer was a very nice guy. He was definitely not a recent graduate, unlike some other posters have complained. He talked about the pre-internet boom days, so I think he has at least 15 years of experience.

The phone screen took 45 minutes.

For the first 10-15 minutes, he asked about my background and why it was a good match for the position, as well as why I wanted to work at Facebook.

Then, I was asked to complete a coding question: "find the minimum depth of a binary search tree." It was not a hard question; any average coder could do it within 15 minutes.

I wrote the code with no hints or help from him. During the coding, he was mostly quiet. At one point, he pointed out a possible bug, which I fixed instantly. At the end, I was trying to optimize the code. He said the code would work and there was no need to optimize it further. Then, he let me ask questions about Facebook for about 15 minutes.

After the interview, I compiled the code, and it really worked without a single compile error.

The next day, I received a rejection letter from the recruiter with no details.

So, the trick is, writing the code is not enough. Your code must be very close to the most optimized version known, and you should be able to write 'close to perfect' code in minimum time.

I googled for similar algorithms and found that my solution was well above average, but not the best one. I guess they expect you to write something very close to the best available code possible, so they can single out the best coders.

So, "move fast, break things."

Find the minimum depth of a binary search tree.