UPDATE: I have added links for the Behavioural Questions

Hello All,

I would like to share my interview experience for Facebook London.

Nationality: Indian
Education: Bachelor of Engineering from a Tier 3 college
Current Location: Amsterdam
Years of experience: 8
Time taken for the total process: 2 months and 5 days

Recruiter Call
April 2021 : One of the recruiters reached out to me on LinkedIn asking if I will be interested to work for Facebook London. We agreed to schedule a call the next day where he asked me about my current project and walked me through the whole process. I asked for a month of preparation time and he scheduled my screening round after 1 month.

Technical Screening Round
May 2021 : I joined the call on the agreed time and we began with the introduction for the first 5 minutes and then quickly jumped over solving the questions. He asked me 2 questions(LC Medium & Easy). I explained to him the Brute Force solution along with Time & Space Complexity. Then I asked him if he would like me to code the approach (I knew he will ask me to come up with a better solution). After that, I explained to him the Best Approach according to me along Time & Space Complexity.
In the end, I asked him questions like "What's your day-to-day looks like & how big the team's headcount is".
Time breakup - 5 mins(intro) + 35 mins(coding) + 5 mins(questions)

I received an email after two days that the feedback from the screening round is positive and they would like to proceed with the Final Loop Interview

Final Loop Interview - Day 1
June 2021
1st Coding Round: We spent the first 5 minutes introducing each other and then quickly jumped over solving the questions. He asked me 2 questions(LC Medium). I explained to him the Brute Force solution along with Time & Space and then explained to him about an efficient way to solve it. Once we agreed on the approach I quickly coded it and walk him through the code along with few test cases.

2nd Coding Round: The interviewer didn't spend time introducing herself and we straight away jumped to the questions, She asked me 2 questions(LC Medium). I started with Brute Force approach and then moved to an efficient one and coded it quickly.

Final Loop Interview - Day 2
Behavioural Round: The interviewer asked me to describe my current project & then jumped over the behavioral questions. They were very standard like

1. Tell me a time when you had a conflict with a colleague and how did you resolve it.
2. Tell me a time when you had a conflict with a colleague and you were wrong. How did you accept your mistake?
3. Motive behind joining Facebook

System Design Round: We spent the first 5 minutes in the introduction & then he asked me to design a system. I gathered all the requirements, walked him through the capacity planning, estimates, database selection, algo, and at last but not least tradeoff of my approach.

After 2 days I received an email from the recruiter that the collective feedback for all of the interviews is positive and they have sent my packet to the hiring committee to decide an outcome which takes place every Tuesday at 10:00 AM London time.
I waited for a week & received an email on the following Friday that the recruiter has received a decision on my packet and would like to discuss the feedback with me. TBH I thought that I am rejected and was a bit sad. Over the call, the recruiter told me that I am selected and they would like to offer me(Yayyyyyy!!!!!)

My Preparation Strategy:

1. All coding questions were asked from leetcode's Facebook company page with slight variation. You should at least aim for solving the top 250 questions. Its all upto indiviual on how many questions would he/she/they like to solve, I have seen people cracking the coding round by just doing 100 quesitions and there were people who couldn't crack the coding round even after doing 400 questions. The gist is that you should understand the logic and should be able to figure out the next variation of the question.
2. Key for cracking the coding interview is SPEED. Facebook expects you to solve the LC medium questions within 10 minutes.
3. Keep in mind that your variable's name should be meaningful, for example writing the below code would cause a red flag for you
   for(int i=0;i<length;i++){}
   instead of i try to use a more meaningful name like currentIndex
4. Try at least 3 test case to walk the interviewer through your code
   4.1. Happy scenario
   4.2 Negative scenario
   4.3 Edge scenario
5. G***** the Sys***** De**** Interview is a good place to start for the preparation of the System Design Round. Search for The Interview Sage channel on youtube to get the latest system design questions for Facebook. System Design Interview channel is one of my favorites on youtube, Mikhail's content is top-notch. For the System Design round, I created below template and solved all questions according to it,
   i. Functional requirement.
   ii. Non functional requirement.
   iii. Capacity & Storage
   iv. Database modeling
   v. API Design
   vi. Sharding/Replication (If required)
   vii. Caching (If required)
   viii. Tradeoff
6. Do not take the Behavioural round lightly, I would recommend you to collect all the questions from the internet(recruiter will also give you some questions in study material) and prepare for at least 1 week. Your answers to the question should be backed original story. To answer behavioral questions I followed the Situation Task Action Result pattern(STAR). Below links should help you to start with the questions
   6.1. Top 41 Behavioral Questions
   6.2 Common Behavioral Questions

Do not lose hope if you couldn't clear the interview process, this is not the end of the world. Identify your weak points and try again. Do not hesitate to put in extra hours, I work 9 to 6 for a startup and then dedicate 4 hours daily for the preparation, I know preparing for the interview process takes a toll on your mental health but it's worth it. Whenever you feel like GIVING UP think about the time why you started in the first place.
Do not listen to the people who say preparation is tough, you cant crack the interview, etc. Believe in yourself, I use to watch this video whenever I felt like giving up. You would get adrenaline boost after watching this
Video: Why Do We Fall - Motivational Video

P.S. I have signed NDA which doesn't allow me to disclose the question details, kindly don't ask for the same :)