I had the one phone interview. The recruiter emailed to set up the interview. This part of the process was smooth, although delayed.

The interviewer called 10 minutes late with no apology. I don't mind waiting for somebody, but I have a busy schedule as well, and it would have been nice if the interviewer had just acknowledged the fact that he was late. He seemed very uninterested in the interview process overall.

He asked no follow-up questions regarding my work (probably because we didn't have much time as he was late). He asked random open-ended CS questions, again with no follow-up questions. This seemed strange, as open-ended questions are posed for the singular purpose of discussion.

Then came the coding problem. I quickly came up with a working solution. I offered to run him through the code, but I was declined. He read through the code and said, "That would work." He opened up the last part for questions. I asked how it was working at Groupon compared to his last job. That was it.

I was asked a very interesting tree problem. Given a tree and a number N, construct another tree such that each node of the tree has either 0 or N elements, except for one node, which has between 0 and N elements. The only other constraint is that ancestry is preserved in the new tree.