It was an internship interview. One week after I submitted my resume at a campus job fair, I received an interview opportunity.

On campus, there was only one question: given floor and ceiling functions, create a round function.

Later, the recruiter contacted me about the time and schedule for an on-site interview. They booked my flight and hotel. Bringing my passport and electronic plane ticket, I started my interview journey.

The on-site interview was in the afternoon. There were four rounds of one-to-one interviews: three for coding problems and one for design problems. About twenty candidates took the interview that day.

Given pre-order traversal result and in-order traversal result of a tree, recover the tree.

Given N computers, how to connect them, and how to check if two computers are connected.