I'm somewhat the opposite. I try to go on interviews on a regular basis, even when I have no interest in switching jobs. I figure that the more I do something,

I'm somewhat the opposite. I try to go on interviews on a regular basis, even when I have no interest in switching jobs. I figure that the more I do something, the better I'll be at it. I also like problem solving, so the majority of questions I get asked are fun to work through. One of the things you get with practice is the presence of mind to not get flustered and to always remember to ask the necessary questions. In the case of this interviewer, once he's asked the question, the first step is not to write either a recursive or iterative solution. The first step is to ask, "How big is my stack?" and/or "What are my bounds (max number of disks)?" Interviewers often ask questions that are deliberately vague to judge the candidate not only based off the answers they give, but also the questions they ask. I've had interviews where I missed answers and still got an offer because I took the time to fully understand the problems they were giving me. I can't recommend practice interviewing highly enough. It may seem like a waste of time, and it will eat entire days of vacation time, but the experience is very valuable and I think I'm a better interviewee and interviewer because of it.