There was only one round of interviewing for this job, but it lasted for about 3 hours total in the morning. This was split up into three 50-minute interviews.

The first interview was behavioral. They asked me questions about what I would do in certain situations, along with what notable projects I had done in the past.

The second interview was a coding interview. They asked me some questions about how I would go about programming something. This was a mix of writing actual code on paper and talking about the approaches, data structures, and time complexities of an approach.

The third interview was a business situation interview, which was a common-sense business skills test. They gave me two different hypothetical technologies that each cost different monthly amounts and different base costs. I had to determine which technology would be cheaper over a given period of time.

I got the job offer later that night.

Suppose you had to design a system for an unknown number of customers to ask customer support questions.

Customers that contacted customer support earlier should be serviced first. How would you design this system?

What data structures would you use?