I had an on-campus interview with HRT at my university, and it was the worst interview experience I've had.

The interviewer was snarky. For example, they said, "Most candidates would respond with X, but okay." They also interviewed me for a different position than I applied for.

While I had prepared for questions on algorithms and data structures, as is typical for any new grad interview, they asked me low-level systems questions. These questions honestly felt like a midterm from a systems class I took years ago and had therefore forgotten.

The questions weren't particularly difficult or novel, but they were simply not what I was expecting or prepared for. They never gave me an interview for the actual position I applied for (Algorithm Developer).

Overall, I felt that HRT was quite unprofessional in their interview process, although at least they rejected me quickly.

A bunch of C programming.

How do you malloc 8GB on a machine with 4GB of memory?

Why are you interested in HRT? (My answer to which was apparently not satisfactory for my interviewer.)