Groupon Software Development Engineer interview questions

Started with an on-campus technical interview with an employee. He asked two fairly simple coding questions, one about binary trees and another about palindromes. This was followed by a 30 minute personal interview over the phone with a recruiter. This was then followed by an hour long coding interview over the phone and coderpad. This was a very techinical interview, asked about data structures to help compute mean and median.

First screen interview was a phone interview with HR which consisted of me going through my CV, why I had applied and what I knew about the company. Second was a technical interview but wasn't that challenging as I was asked at a high level how I would design a system. No programming questions where asked which I found a bit odd. Got invited to come into the office for a 4 hour interview. Got to the office only to find out Groupon don't have a reception (there is one for the building but that just got me to the right floor) so I had to ask some random employee walking past to get someone from HR for me. Had an hour each with the 4 interviewers which were all technical based interviews and all but one didn't involve using the whiteboard. Got asked to code up on the whiteboard a collection without using the inbuilt one, some data structures questions, basic Unix questions and at a high level how would I design a system architecture. I found all the interviewers very friendly and helpful (one of them was less so) by helping you along with the questions.