Hi Everyone, I attended interview with Facebook for Seattle, US location. I wanted to share my experience with everyone. Please find details of questions below. Some of them, I do not remember exactly. They did not ask me to sign any NDA as far as I can tell.

Years of experience: 10+
Date: 11-FEB-2021

Phone screen:

1. Delete node with specific value from Linked List
2. String based question, but I forgot the specifics.

Virtual Onsite:

1. System design (Write an API to fetch a resource like image or video and give it back to a mobile phone client). I made the mistake of trying to scale too early in the design. But it was very hard to understand what the interviewer was expecting. I could have asked more clarifying questions, but I was very nervous and did not do well.
2. Coding round 1: Problem #1: Given an array of non negative numbers and a target, find the subarray that sums to the target. Problem #2. Convert inorder traversal of binary tree to circular doubly linked list. I was not able to come up with the most efficient approach within 20 mins for a question. I coded the brute force approach for problem 1, and after finding the efficient approach using sliding window, interviewer asked if I can code in 30 seconds. I was thinking in my mind, 30 seconds was way too much.
3. Coding round 2: This round killed any hopes I had of joining facebook. Problem #1: Implement an iterator that has a hasNext() method and next() method for the inorder traversal of a binary tree. I cannot precompute the traversal and then use the precomputed value. Problem #2: Given a string source ["deb", "axy", "ben"], and a target that contains characters [a, d, b] find if the source can be re-ordered to match the target character. In this case, the anwser should be boolean. It took me 5 minutes to understand the problem. I felt as soon as the interviewer saw me, the mind voice inside must have said, dude, you are not getting this job. But the interviewer tried giving me one hint, and sadly, I knew it was a hint only after the interview was over.
4. Behavioral: This went well
5. Coding #3: Problem #1: Merge intervals Probelm #2: Right side view of binary tree. I did this round well and was able to solve both the problems. But I had prepared hard for two months and solved these two questions before.

Got reject call after 3 days. I was devastated, but I was expecting a reject. I also felt very bad that I cannot match the expectations. I was thinking after the result, how did facebook hire these many engineers with such strict interview. Maybe in their previous generations, all they did was code. It will take me a few more days to get over it. It was a very difficult interview according to me. Unless I have solved the questions they ask at least twice, I wouldn't be to solve their questions.