A very typical process with nothing unusual. The timeline is also pretty flexible.

• Phone calls with recruiters.
• A technical interview involving LeetCode.
• An onsite interview consisting of two rounds of LeetCode, one round with a hiring manager, and one round of system design.
• A later interview required another round focused on a specific area of expertise.
• Conversations with a director occurred once or twice.

From there, an offer is sent. Discussions with the recruiter follow to negotiate numbers. This is a very easy process; consulting Levels.fyi can provide an idea of reasonable salary expectations.

Topological sort question:

Just study topological sort.