Status: 5 YOE, 500+ questions on LeetCode solved in a year.
Position: E5 at Facebook
Location: London
Date: June 2020
Result: Pending

Hi,

Giving back to LeetCode community and sharing my experience :)

Initial communication

I was contacted by a recruiter in LinkedIn (and e-mail at the same time) in spring of 2019. At that time I was not ready for interviews, so I asked to ping me back in summer 2019. And so, in spring 2020, I was contacted again :)

Phone screening (45 mins) - May 2020

• a string question, LC easy - solved it without issues quite fast
• a graph question, LC medium - also solved it optimally

Overall impression: the interviewer was extremely nice. I got the impression he was interested in my success. The feedback didn't really contain anything to improve, as both problems went quite smooth.

Both questions are in this list.

Virtual onsite (4 x 45 mins) - June 2020

Coding interview 1

• an array question, LC easy. Solved it quite without issues, but manually checking the testcases took me overall first 20 minutes.
• a dp grid question, LC medium. I was ready to implement the solution with O(n) solution instead of O(n^2) , but the interviewer wanted me to figure out a solution with O(1). We spent the remaining time figuring it out and writing the formula, and I didn't get to write the solution at all.

Overall impression: I didn't quite like the interviewer, especially with the second question - as I was ready to go with my approach, and I would expect for them to let me code it when it was clear that the time was going up. I've had an experience before at Google interview when I didn't get to write the code, and usually the score for such interview is quite low. So I am expecting a mixed feedback here.

Both questions are on LeetCode and tagged by Facebook, but not in this list.

Coding interview 2

• a string question, LC easy. Solved it quite fast, but had to clarify to interviewer why I am using an int[] array of length 26 to count the characters which was fun.
• a binary tree quesion, LC medium/hard. I came up with the solution and wrote it, but the interviewer considered it as brutforce. We ended up with discussion on optimizations, and after a hint I suggested the one which the interviewer was expecting, but didn't have the time to code the optimized one.

Overall impression: I liked the interviewer, they were very kind and supporting. I could have done a bit faster, if they haven't asked so many clarifying questions. It was a nice experience. I am expecting a good feedback here.

A question similar to second is on LeetCode, but I don't think the first one is.

Behavior interview

• a lot of questions like "tell me a time when", "how did you react". What helped me here is the chapter from "Cr-ing the co-ing interview" about preparation to this kind of interviews - especially the part where you make a table with your previous projects and the things to be marked.

Overall impression: I liked the interviewer. I don't really know how they give scores, so honestly I am not sure what to expect. But looks like they were interested, supported the discussion and said things like "thats a nice insight" and "that looks like a good experience", so maybe things are ok.

System design interview

• a question not listed in this list.

Overall impression: I haven't been really preparing for this interview, I just viewed several videos with overall concepts of designing systems. I think I failed it, because it was quite difficult for me to figure out how to satisfy all the requirements, and at the end the system contained very few pieces and I am still not sure all of requirements were covered. Also while implementing I kept violating the requirements, and the interviewer kept suggesting me that it won't work because of that.
I think the feedback here will be mostly negative. Main takeaway - prepare for this one, mock these interviews, make sure to design systems from scratch at least in 5-10 mock interviews before actual one. My lack of practice was obvious for me here.

Overall thoughts

I mostly liked the interviews, because the people seemed to be both knowing and pleasant to communicate, which may be a rare combination. They supported me during my pauses, and helped me going on with the thinking process. If not for 1st onsite round, overall impression would be just great.

I got slightly tricked in onsite rounds by coming up pretty fast with not-a-bruteforce solution, and being sure about it and not being very open-minded to further optimizations. Mostly it was like a standart solution article on LeetCode:

1. Brute-force approach [Time limit exceeded]
2. Optimized brute-force (or just a better way) [Accepted] <----- I was usually here, happy about it and not eagerly diving further
3. Even better way [Accepted] <----- This is what an interviewer expects

This is a takeaway for my future interviews - not to be happy too early with coming up with a solution, and continuing thinking unless the interviewer is fine and just suggests writing it down.

Results

I heard back from the recruiter after 9 days.
The feedback was that all of the interviewers suggested me as a hire for E4 and not for E5.

As there is currently no headcount for E4, recruiter said he is going to write back to me in 3 months and we will catch up.