I was interviewing with Microsoft last semester for a SE internship. At the end of the interview with a senior engineer, we were just chatting about various top

I was interviewing with Microsoft last semester for a SE internship. At the end of the interview with a senior engineer, we were just chatting about various topics. This is one topic that we talked about. His response was something along these lines: "Of course we do not write code on whiteboard everyday. Of course we do not write code to detect if a graph is acyclic (my interview question) on a daily basis. Of course we do not put our engineers on the spot with these types of questions. However, when the time comes, may it be only once in 10 years, we know that we have hired the right people because these questions show your thinking abilities - not if you know the answer or not." Btw, I didn't get an offer, but I'm going to Amazon where I had very similar interview process as Microsoft.