I was interviewed once by someone who would cut me off after just a sentence or two. He asked a fairly open question like, "Tell me about hash tables." I knew I should have just said, "Lookups are constant-time," but I started off with a description of their behavior instead, and sure enough he cut me off and said, "Lookups are constant-time." Some people are just not very good interviewers, but also some tech people's rules are too iron, with no exceptions, like they can memorize but not think. They say interviews are a two-way communication, and that one certainly was. :-)