I applied through a campus recruiting event, and after a week or two, I received a phone screen.

The questions were pretty easy, standard algorithms.

Then, after a couple of weeks, I got an onsite interview with them.

It consisted of four interviews, around 45 minutes each. The questions were a bit harder, and a lot of them required me to actually write out code.

Given an input stream of indeterminate length, how do you return a random member of that stream (with equal probability for each)? You're not allowed to store more than a constant number of inputs, and you can only go through the inputs once.