I only went through the initial phone screen.

In retrospect, it seems that either the interviewer was working from a checklist, or they had so many applicants that they were eliminating anyone who didn't awe them with greatness. I say this because I was very surprised to get a terse rejection email a few days later. The interview was so simple and perfunctory that I can't imagine what I said (or didn't say) that would have eliminated me.

I emailed the HR contact who had set up the interview with a polite inquiry about what they were looking for, and how I might better fit their needs if I applied again in the future. My email did not receive a reply.

Given an array of integers, how would you remove all duplicates in linear time, i.e., O(n)?