2 rounds phone were all algorithms. Basically not hard. Onsite was all about multi-threading. They will go into very detail coding about multithreaded patterns. please be prepared for common patterns. algorithm questions were quit basic, like tree traverse, sort, graph search. design questions were not hard either. please refresh your memory for common design patterns of OOAD. Java and C++ are both their primary language. you can choose either and helpful to have both. 2 rounds were introduction to 2 different team by their director/manager. One for cloud and hadoop is very fun.