I had two rounds of telephone interviews, each lasting 50 minutes, for a total of 2 hours.

It seemed they would ask many algorithm questions, but I had time to work out only three of them.

Beyond solving the problems, the interviewers were more interested in my approach, how well I could discuss my thoughts, and my understanding of time and space complexity, rather than my coding speed or code perfection.

Having a good headset for phone interviews is extremely important. With both hands typing, you won't have a free hand to hold the phone while talking.

They asked me matrix operation questions and a tree operation question. To prepare for such questions, the easiest way is to start preparing with LeetCode and other online judges as early as possible. A two-week rush will not yield very good results. Some project background was asked about, but there was no deep discussion.