Two rounds - 1 hour resume round - went over the specifics with my resume and what I had worked upon, questions were very thorough with every little detail I put on my resume.

1 hour technical interview - went over my C++ concepts and skills - pointers vs references, std::map and std::unordered map, std::vector, std::list implementation details, pros and cons of std::list over std::array, move constructor, copy constructors, etc.

You should implement a std::string class in C++.