Facebook | E6 | London [Reject]

I was referred to a recruiter by a friend who had previously interviewed at facebook. The entire interview process spanned about a month and a half, starting in March and concluding in mid-April. Each round was 45 minutes long, with coding rounds featuring two questions each.

Screening Round:

I faced two coding questions. One was related to palindromes (though the exact problem isn't shared), and the other involved finding a path in a given binary tree. For the binary tree problem, I also had follow-up questions to solve it without using a global variable and to adapt the solution for any n-ary tree. I managed to complete both questions within 35 minutes, and the feedback was very positive, leading to an E6 position consideration.

Coding Round 1:

This round also had two coding problems. The first was about merging two sorted arrays. The second involved merging contacts with domain names into the minimum number of groups; the interviewer suggested treating contacts as graph nodes, generating edges for common domains, and then using DFS for connected components. The feedback for this round was good.

Coding Round 2:

Again, two coding questions. One asked me to find an element in an array and return a random index if multiple occurrences existed. The second problem involved using two given APIs, move() and isTarget(), to determine if a target was present in a grid that contained a source and target at some positions. I solved both of these with some hints from the interviewer, and the feedback was good.

Product Design Round 1:

As I was interviewing for an E6 position, there were two technical product design rounds. The first involved designing an API for a newsfeed, similar to Instagram or Facebook, while considering multiple client types. The feedback was that I needed to discuss more about the scalability of the system.

Product Design Round 2:

The second product design round focused on designing a system to handle live comments for videos. The feedback indicated that I needed to delve more into the low-level details of the system.

Behavioral Round:

This round consisted of standard behavioral questions based on my past experience, covering situations like handling teams, conflict management, and my learnings over the last 2-3 years. The feedback was positive.

Ultimately, considering the feedback from the product design rounds, I received a rejection. The recruiter explained that product design is a very critical component for E5 and E6 positions, and despite very good feedback in other rounds, they had to reject me on that basis. I hope my experience can be helpful to others.