I applied in September and heard back within three hours; they wanted to interview me. I had to wait a few months, however, because they wanted to interview full-time applicants before interns. So, I waited until December for my interview.

It was a very informal interview with relatively easy questions, involving creating my own hash table and dealing with collisions for inserting and searching. Ultimately, I was not offered a spot, but the people there were quite professional.

There weren't really any hard questions. The interview I had was purely technical, with relatively simple questions.