NVIDIA interview questions

I submitted my resume onn their website and got their recruiter email in 2 weeks. Then have a phone call interview with their team leader directly, after the call, on the 2nd day, the recruiter gave you response. Their feedback and arrangement is very fast.

3 telephonic discussion followed by 4 f2f interviews. I had a very bad experience, after going through 7 rounds of interview I did not get any feedback for HR, which I believe is very unethical. It was complete waste of time, except 1-2 interviewers they were all very sub standards. Hiring manger asked me about BST and he did not even know the time complexity of a search in BST. I really did not expect this low from Nvidia.