If this actually happened the only signal I would get from this interview is that the candidate is a egotistical asshole. No hire. - It's always good to not as

If this actually happened the only signal I would get from this interview is that the candidate is a egotistical asshole. No hire. - It's always good to not assume that the candidate is familiar with a given question, no matter how well known it may be. Maybe they're from a different country, maybe they're from a different industry altogether making a transition. - I bet if the question was difficult or complex the interviewer would say "omg that's not realistic, would never use this in real job". Then again, I'm also in the minority of HN users who like coding/problem solving interviews so what do I know.