Reached out to a recruiter, who then followed up and set up a phone screen.

An interviewer had some technical difficulties. A few minutes later, we got started. We had to reshare the link.

The first question was not in my scope of knowledge. The interviewer was nice enough to explain the first problem but realized I was not familiar with the topic, so they switched questions.

The second question was related to binary trees, and the interviewer even told me that the majority of candidates did not know how to solve the problem.

Find if a given binary tree has duplicate subtrees.

(Just two leaf nodes of a parent do not count as a subtree in this question).