Just basic questions about C/C++ and memomory management, fragmentation, smart pointers, BOOST, SQL. Also a lot of quesitons about RAII and multithreading (mutexes, threads, atomic, deadlocks etc.). A bunch of behaviour such as: What would you do if you have this kind of problem?

There was very difficult communication process between HR and applicants. I waited a long time to receive the results of the interviews I passed. Finally I received positive feedback and was invited to an interview with Team Lead but was unexpectedly rejected the day before without further explanation