When I read this: Need help on this Interview question I wondered if it should be considered on topic or not?
If this question is acceptable, I'd expect a huge flood of "How to answer this interview question?" questions.
It doesn't matter to me either way, but in other non-stackexchange forums, I've seen this flavor of question become overwhelming. I could easily imagine a new stackechange community devoted entirely to asking and answering interview questions.
There is a precedent to be set here.