The interview process consisted of:

• A 30-minute HR call.
• A 30-minute hiring manager call (general CV overview).
• Four 45-minute interviews with various engineers, including one behavioural interview and the rest mostly technical, featuring programming tasks.

Overall, the difficulty was not too bad. One programming task was quite challenging, but that's relative.

They provided helpful information on what each interview would roughly cover, aiding preparation, although this information wasn't always fully accurate.

All interviews were quite relaxed and friendly. The interviewers took time to explain the role and the company.

I think the process is a bit long. I don't believe they need six calls to determine a good fit.

This involves four hours of actual interviewing, plus significant preparation time, making it a substantial time commitment. Consequently, I'm unsure if I would apply again.

How do you go about debugging things?

How do you learn established code bases?

Bit manipulation, graph data structures, general C++ and Python.