In my opinion, the way the interviewer screwed up wasn't giving you that question, it was rejecting you for only getting 90% of the way there. The purpose of a

In my opinion, the way the interviewer screwed up wasn't giving you that question, it was rejecting you for only getting 90% of the way there. The purpose of a simple artificial question like this is to act as a binary filter, separate people who can program (and will take a decent shot at it) from people who can't (and will just stare blankly at the board for the allotted fifteen minutes). An interviewer who starts expecting it to be more than that is just adding noise to the selection process.