Status: 11+ years Experience on JAVA, J2ME & Android full stack. Expereince in Mobile and Automotive industry
Position: SDExx at Facebook
Interview Location: Phone screen and onsite @ FB London UK
Date: Mid December, 2018
Final Status: Not selected. Got feedback that all round went excellent apart from 1st coding round in which i took bit more hints than expected to solve. Even though I solved the problem, expection is coding rounds to be clean black and white.
Prepration time: 30 days for online screening and 2 months for onsite (was lucky to get this because of visa processing time and availibility to interview panel). In my college days I was on above average on algorithms but for past 11 years have never practiced. Based on my experience i would suggest if you were good at algorithms and problem solving, then 3-6 months of dedicated and planned practice should help to crack the interview.
Prepration methodology & tools: There are many resources available online but below are few things i used
- LeetCode - Came to know from a friend and this definetly helped. Just a suggestion focus on solving problem rather than targetting high performance unless you want to go exploratory.
- FB's HR shared links for video and tools
- Cracking the coding Interview book
- Youtube videos on - Behavioural and Design rounds
- Plan to improve your soft skills: For example, I am not sure if this is true for all but while coding or problem solving i have tendency to remain silent and get into my zone, but as i understand from my study that these interview is more towards understanding of how you think rather than if you are able to solve a problem. Hence i trainined my self to put my thoughts out while thinking. This helped alot in having interaction going in all rounds of interview.
- Coding Buddy: - Find a person with whom you can work on solving problems. Idea is to be more vocal while you code and express your thinking process. Tell your friend to give genuine feedback which you can use to improve.
- White board coding: - Do practice this. Its not only about, to see, if you can write on a white board, but also for you to understand how to organize your content on board. Helped me both in coding and design rounds.
Details of Interview Rounds:
- Technical Online/Phone Screening:
- 45 mins discussion
- live coding on tool - Compiling is not required and if you dont remember a API signature then also its okay.
- 2 medium difficulty problems were asked - Number of problem can vary as my friend was asked only 1, high difficulty problem. It is better to ask interviwer how many questions would be there, so that you can plan time.
- Tips :
- Make sure your internet speed is good and call lines are not disturbed. I did all setup provided from FB a day prior and tested all are working.
- Make sure you know how to use the tool by using practice session dont leave this for last moment else you would end up wasting time.
- Keep speaking your thoughts aloud
- If you solution require to call some standard API which you cannot think of then you can write dummy API and explain the behaviour for same.
- Big O understanding is really important for all technical rounds. Do try to understand concept well and how to calculate one for your solution. Was not asked any specific question like what is Big O, but for every problem interviewer wanted to know what is complexity and if there is possible solution to reduce it.
After clearing telephonic my onsite round was scheduled @ London office.
- Coding round - 2 separate sessions:
- 45 mins discussion each
- White board coding
- 1st round - 1 high difficulty problem was asked - i did solved the problem but took too many hint to arrive on final solution.
- 2nd round - 2 medium difficulty problem were asked
- Tips: There are lots of material online on what to expect and what to do in these rounds. Few things which helped me are
- Practice using pen and white board
- Find a coding buddy and spend some time practicing
- Be in discussion mode and listen to what interviewer is saying, they are suggestion to improve and hint if you are not in right direction. I missed few hints and took bit too much time to react and that costed me my selection.
- Lunch break: - one person was assinged to show me around in campus and to take me for lunch. I discussed with him about company HR policies and living in london.
- Tips: Since this persons feedback is not consider for interview you can be more open and talk about doubts and any other questions you have to make this career move.
- Android Design / Architecture Round:
- 45 mins discussion
- White board designing and discssion
- Was asked to design and provide thoughts about an app like instagram. I talked about features, android platform challanges, performance aspects, testabilty etc
- Was asked to specfically to take care of 1 secnario, and we discussed bit more of that part in details.
- Tips:
- Thumb rule - 45 mins is too short of any design to be fully developed, hence you have to have enough ideas and thoughts to keep talking. If you are not able to find thoughts to talk about, then you are not going to make it.
- Focus on width in terms of different aspects of your solution rather than deep dive into one area
- Lead the discussion and do not wait for questions to be asked.
- Understand the technology area and industry you are being interviewed for, and study all nuances and use cases around it, you should have enough in your kitty to keep the discussion going.
- Behavioural/Motivations Round with coding:
- 1 hour discussion
- Real life scenario based topics were dsicussed. I didnt counted but must be 7 to 8 topics were discussed. Questions were based on my experience and basically in direction of
- what i have done in a specific scenario
- If I have to do it again how i will improve
- What are my area of interests in this industry and how do i see my future.
- In end of interview 1 medium difficutly level problem was asked. Time provided 15 mins
- Question: https://leetcode.com/problems/valid-parentheses/
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- Tips :
- Important is to be truthful and keep it simple.
- Bring out details of what and how it happened while providing your answers
- Since there is no right answer dont try to make one... it is interviewer job to identify if you are good candidate for position or not, and if in worst case scenario you are not selected due to this round then also i believe it is better to be rejected than getting a job and not able to perform.
- Have few questions of your own to ask which can show that you have given thoughts about this job and are also evaluating your own grounds. Actually for each round you would have 5 min to ask such questions.
- Tips :
Overall Experience
FB have given me enough content and time for me to be prepared for the interview. They wanted me to be in my perfect mindset when taking interview. The overall experience was really wonderful and i really want to appericiate how HR team organized. They took care of each details of, how i am going to travel, will i have enough rest before interview etc. All expense are taken care by them, i have to pay certain item by myself but got reimbursed.