It was in the morning. For sure I have clear idea how to solve this simple question. But I got stuck when debugging (what I need to do was just to switch the order of 2 loops without changing a single character). This guy, the interviewer was just laughing without help till the end of time. Well, if you don't want to hire, then don't. Why are you so proud of knowing the solution to the self-designed question and laugh at people?