BBVA C++ Quantitative Developer interview questions

I submitted my application online and then I was called by the recruitment agency/HR department. In the 1st round they went through all the basics of C++ from OOP related concepts to finding whats wrong with the code and how can you correct them. After that I had typical HR interview and basically I was asked whether I would stay in Spain for long or not. Then after this I had another 2 round of interiews. One of the rounds was about design pattern and related concepts. Next round was mix of mathematics and programming. Finding some expectation, how to obtain a random number from a given distribution. I thought my interview was good enough but I guess there was someone better than me who got the job. As such I didn't get any feedback about what did I lack and what exactly were my schortcomings. Also in the last round we had some language problem due to my not so fluent Spanish. I had to kind of guess what the interviewer is trying to ask and then I had to answer.