Applied online, as well as reached out to head university recruiter (Avery Hale). Process went OA (did not ace) -> phone screen -> 2x45 technical, 1x45 informal chat w/ director -> offer. Note that OA is only offered in C, and same with technicals. It is expected that you know your way around C regarding syntax, and to a lesser extent, the lower level parts of C (bitwise operations, etc). For the 2x45 technical, it was maybe 15 minutes, 20 minutes of behavioral/technical Q&A, then 25-30 minutes of coding problem. The chat with the tech director had NO technical or behavioral, just a conversation about what it's like to be an intern at HPR.