The first screen interview was a phone interview with HR. It consisted of me going through my CV, why I had applied, and what I knew about the company.

The second interview was technical, but it wasn't very challenging. I was asked at a high level how I would design a system. No programming questions were asked, which I found a bit odd.

I was then invited to come into the office for a four-hour interview. Upon arriving, I discovered that Groupon does not have a reception area. There is one for the building, but that just got me to the right floor. I had to ask a random employee walking past to find someone from HR for me.

I had an hour with each of the four interviewers, all of whom conducted technical interviews. All but one involved using the whiteboard. I was asked to code up a collection on the whiteboard without using the built-in one. There were also some data structures questions, basic Unix questions, and a high-level question about designing a system architecture.

I found all the interviewers very friendly and helpful, with one of them being less so, by assisting me with the questions.

Implement data structures up on the whiteboard.