There were four interviewers.

60% of the questions were from LeetCode.

I will definitely recommend solving as many problems on LeetCode as possible.

However, that doesn't mean you shouldn't spend time on system design and object-oriented programming.

These are regarded as common knowledge, and if you can't answer them, your chance of getting an offer becomes very small.

Overall, the interview process was OK. They did not ask too detailed or tricky questions.

How do you serialize and de-serialize a binary tree?