Overall, the interview process was fantastic! I loved it, though I did not get the offer.

The sourcing recruiter contacted me on LinkedIn when I was not looking. After about six months, I contacted the same recruiter and received a prompt response from that point until the end.

I went through the first technical round of the interview onsite, as I was local to their HQ. They prefer onsite, though one can choose a phone interview. For me, onsite worked out well. It was nearly a one-hour interview with one person. There were two programming questions: one on linked lists and another on BSTs. For each, the task involved finding the solution (easy to optimal) and then writing the optimal code. I did this pretty well as I had prepared for data structures and algorithms.

They immediately called me for a full-day onsite interview. Again, I prepared a lot on data structures, algorithms, and related problem-solving. And boom... that was my mistake. I forgot to focus on the system side (locking, synchronization, deadlock) in detail. There were five interviewers, each for 45 minutes. No one asked about data structures or algorithms. Two interviewers asked about locking-related questions, one about design, one manager, and the last guy did a combo of everything. Mostly, I screwed up on the locking-related questions, as I took many hints and a long time... sigh..

Everyone was professional. Communication was prompt and fast!

Design a backend system to run an app like Facebook, where the query is to get two levels of friends of friends. This is an open-ended question.