I first had a phone interview. The interviewer asked a lot about personal experience and projects, etc.

Then, they dived into the questions. There were three questions:

• One was about sorting a stack using only another stack. This can be resolved using insertion sort.
• Another was about circular linked lists, which I found particularly difficult to answer on the phone.
• The last was about memory limit concerns in large system design. This was likely prompted by my resume listing OS development. It was a conceptual question, and I think I answered it pretty nicely.

Circular linked lists are tricky. You don't typically learn about them in school, so you have to think outside the box.

Usually, using two runners is a way to approach this kind of problem.