guys, interview problems are not fixed|
we will often adjust what to ask, based on interviewee performance, and try not to make the candidates feel bad.
if the perf is really under par, we won't dig for the hard questions and embarrass the kids
and if someone is really good, we ask many follow on questions to probe how deep one can go.
just because you felt you have answered all the questions does not mean you really "got" all of them
whether or not you feel good after an interview bares no relations to the final outcome.
there are many other factors like how you communicate, your coding style, did you think of sufficient test cases, do you care about efficiency, etc
there's also "culture fit"