Location : London
Post : Software Engineer, Machine Learning (MLE)
YOE : 4

I had my phone screen with facebook for MLE recently.

Question asked :
Let's say we have database all the customer entry time and exit time to a store, so we want to maximum number of customers at a time in the store.
A small follow-up in our discussion was also that we might have 6 months or year of customer data on which we may have to run our algorithm. (in a way saying, complexities can't be high).

The question essentially comes down to finding the point where maximum intervals overlap. You can find on it if you google. I could not find the same question in leetcode. Perhaps there is an equivalent question here but I'm not aware.

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I did terrible I think - I was only able to solve this but not in an optimal manner. Couldn't even get to the second question. I surely need much more practice. I had done only about 50 questions which were FB tagged and went through CtCi and EPI.
To anyone who reads this, it would be good if you can link me to some great posts for proper preparation from leetcode for FAANG.

Thanks, hope this helps.

P.S. No clue on E4 freeze or anything. I believe discussions regarding those happen if you clear the interview. I can't see any "level" assigned to this position on their recruiting portal. So, not sure what would've happened if I would've cleared it.