First, I had a phone interview. The question was fairly straightforward: multiply two very large numbers given as strings. The interviewer wasn't looking for any tricks to solve it. As others have mentioned, quick, clean code seems to be the key. Unfortunately, the interviewer had a very thick East Asian accent, and talking over the phone made things worse. I had to ask him to repeat himself quite a few times. It was probably me, but at times I couldn't even tell when he'd asked a question because of the inflection. It must have gone well enough, though, because I received an on-site call.

The on-site consisted of two interviews, each 45 minutes long.

In the first one, I took a bit of a hit because a) I couldn't see the solution right away, and b) it took me a while to get up to speed and code the solution. I did manage to finish it, and it seemed relatively bug-free. Again, as many people have mentioned, the interviewer seemed quite young, just a year or so out of school, and he didn't offer much feedback, positive or negative, as the interview progressed. Once he'd given me the question and the hint that got me started, he was busy with his iPhone, rarely looking up. That kind of sucked.

The second interviewer was much nicer – probably one of the best I've interviewed with. He provided lots of feedback and encouragement and was accepting of different trains of thought and non-standard answers. He also seemed like a really nice guy.

Overall, it seems to be the case with Facebook that:

• Your interview really depends on who you get.
• They seem to value quick, clean, bug-free, optimized code on the first try more than anything else.
• Questions are of average to above-average difficulty (if you've prepared!).

Write a function to take a BST and a value k as input and print the kth smallest element.

Write a function that takes a binary tree as input and performs an In-order traversal, both recursively and iteratively.

Write a function to take two arbitrarily long numbers as Strings and multiply them, returning a String representing the product.

Write a function to calculate the square root of a number.

Given a binary tree, write a function to find the length of the longest path in the tree.