The phone interview is mainly about C++, Java, and code problems.

They focus more on C++. The questions are not hard, but they ask them very detailed.

For example, they ask about virtual functions in great detail, including how the vtable is implemented, and there are often follow-up questions.

One tricky aspect is that previous questions are helpful for solving subsequent ones.

Basic concepts about C++, such as virtual functions, and the difference between Java and C++.

Data structures and algorithms, including quicksort partition and finding the median element of an unsorted array.