Done with my FB phone screen this week.

Two questions:

1. Easy (not on LC) - this was a tree problem, not that difficult.
2. LC Hard tagged FB

The interviewer was ok with my solutions and I was talking about time and space complexities all the way while describing my approach. For the second question I had to write a few helper functions, and a class.
I wanted to use a inbuilt library and the interviewer said you are expected to do that and was in general happy that I asked.
Once the approach was discussed and accepted, I wrote the code, and ran through an example. Found a small bug, fixed, it and was done. The interviewer seemed happy (or so I think), he seemed more like 'yes you solved both problems'.
Asked a question I had and was done with the interview with 5 minute to spare in the alloted 45 mins.

Awaiting result.