The interviewer wasn't helpful. A little nudge in the right direction goes a long way during tech interviews. I ended up wasting a lot of time on a more efficient(but complex) solution for the programming problem for which the brute force solution(which i had mentioned) would've been sufficient, and had the interviewer clarified that it would be acceptable, I could've gone with the latter and had a different outcome to the interview. And hence my point that interviewer feedback during the interview is of utmost importance.