It was different from the previous interviews i attended. It was pair programming which in my opinion works but is resource intensive, i mean more time is needed when two people are communicating and less time when you and your mind are communicating. But here time was fixed 1 hr (that includes 3 introductions, two from panel and one my own. I don't know why IT still do this formality and not just start the meat of interview right away) Anyways, back to point , interviewer mentioned in start that it's a difficult problem and we willn't be able to solve it in one hr and his last comments when he rejected me were "unfortunately we reached only half of solution, in one hour. So we can't proceed to next round." So better you clarify it in start what all are P0 and P1s. Second thing to watch out for is - interviewer after telling you the problem will start typing the pseudo code and ask you question "okay so how will you solve the conflicting expiration time aspect of the given problem (which datastructure will you use ) ? Here my suggestion would be to take a pause and ask the interviewer to wait for sometime to let you develop your own thinking or solution skeleton before he starts driving the interview his own way.