Renaissance Technologies LLC Research Infrastructure Programming interview questions

The second interview was to my surprise with one of the big heads of Renaissance, long trajectory, impressive career. He explained the process. If successful at the first technical interview, they'll bring you to their HQ and have a full day of interviews with the team so the first technical interview is to check if you know the basics to have an articulated discussion with them in the next step. He asked me questions regarding C++, like default initialization, move semantics, etc. Over the phone he gave me a couple of lines and ask me what was happening there (in terms of memory allocation... etc). He asked me about STL containers I work with and which ones allowed access to its elements in constant time and asked about the underlying structure for certain containers. Then he asked me to code a function and I failed because I didn't know the specific syntax for multiple functions to handle files. So there's an expectation of being perfectly fluent in C++/STL. The experience with the interview was positive and even though it finished earlier he explained clearly why and the expectations. The interviewer can be read as someone blunt but he was always respectful. I prefer honesty over "you'll (never) hear from HR in the next couple of days"