NVIDIA Design Verification interview questions

I had a first technical interview where I was asked questions related to a digital systems course and C programming, and I was also asked a puzzle. In the second interview, the content was similar, but I didn’t pass. Following that, the hiring manager wanted a more prestigious academic institution (he explicitly said this to me during the interview).

A series of phone screens (2) and an onsite interview based on the results of the phone screens. Typical process, HR was quick to respond with scheduling. The first phone screen covered basic software concepts/questions with a few verification related questions, the interviewer was on time, introduced himself, what his role was within the company and overall seemed organized; asking meaningful, job related questions. The second phone screen was the polar opposite. The interviewer was just under 10 minutes late, introduced himself, and asked "puzzle" type questions where the rules changed as we progressed. After asking the question, I could hear him typing in the background and at times respond "uh-huh..yeah"....even when I wasn't speaking. Very surprised given the reputation