I first had a phone interview and answered a few basic computer science questions. During the on-site interview, I had about 6 hours of interviews (1 hour per person) throughout the day, including a lunch interview. The "loop" usually gets cut after lunch if you don't make the cut. Fortunately, I went the whole day. At the end of the day, you usually sit down with someone higher than the hiring manager to discuss non-technical topics, so they can get a feel for you as a candidate and your potential non-technical contributions to the team.

You have two linked lists that merge at some node. The lists could be billions of nodes long. Find the node where the lists merge in the most optimal time while using a low amount of memory.