I interview for facebook london position for iOS Engineer position.
Current:
iOS Engineer in India (Growing startup in India) (2 Years full time experience and 1 year of internship experience)
Interview date:
July 2021 (Dont remember exact date.) All rounds were 45 mins only

Recruiter contacted me after apply for job in a week. She informed me about interview process.
5 Rounds in total.
Phone Screen:
2 coding question

1. leetcode easy problem.
2. you are given a data stream. you have to find sum of k numbers every time for k numbers in a data stream.
   I cleared this round.

Onsite round:

1. Coding round (one normal coding question and 1 iOS specific question)
   (I did well here but I dont understand why I was given feedback of not doing well in k closest points to the origin. Can anyone give feedback what is better. I verbally gave solution of quick select for which interview asked what is worst case time complexity. I answered o(n^2). After which I gave max heap solution --> O(nlogk). I did not understand where did I missed.).
   a. I dont remember the question very well. Given a uiview array. you have to find parent view.
   [view1, view2, view3]. You dont have access to parent. Neither you have access to which node is start node.
   --> Approach hashmap where you store child to parent relationship.
   b. K Closest points to the origin. I gave both quick select solution and maxheap solution. (I was given feedback that I did not do well in this question by recruiter. is there any better solution than these 2. Quickselect --> O(N^2) and heap is O(nlogk)). I coded up heap solution.

2. Coding round 2
   (I did well here)
   a. clone a graph.
   b. ios specific search question. (easy question for any app engineer.)

3. Behavioral round
   (i was given negative feedback here. Company wanted someone more senior than me I guess. I told to work on how to handle ambiguity, Conflict situation)
   Interview asked me about my company. General behavioral interview questions. In my current company I am leading iOS development team. My current company is a small company. Interviewer was not impressed since I did not have any senior in my current company. I thought interview went very well. I got feedback from recruiter that this round was deal breaker.

4. App design round.
   I did damn well here.
   I was asked to design feed (app side only). I enjoyed this round.

Every interviewer is polite.

Guys, I need your help how should I prepare myself for behavorial rounds for level 4 engineer at facebook. I guess my current behavioral skill set is of level 3. Any help
I have upcoming interview at quora in 2 days please help.

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