I had a similar lucky break when interviewing for my first real job at $FANG. They asked me a question which I happened to have done a research project on. So not only did I give the optimal algorithm I also was able to teach the interviewer some new aspects of the problem. I got the job very easily.

Conversely at my interview for $FANG2 I got unlucky and didn’t do as well. So I didn’t get that job.