I had two technical interviews and one interview for my questions only.

For the first interview, I knew the problem already, so I let the interviewer know. They asked a different one, and I started to think about it. After some loud thinking and sharing my ideas/challenges, I came up with a proper solution. I also mentioned how to extend the solution to a more generalized one and came up with a design for a distributed system that could serve high user traffic demand.

The second problem contained two sub-tasks, and I coded both. For the first sub-task, there was enough time to go over time/space complexity and code a slightly more complicated version of the problem.

There were silent listeners during both sessions, along with the main interviewer.

The first question was about how to implement get_hits and log_hits methods for website visitors. get_hits would return the number of hits in the last 5 minutes. The follow-up question was how to scale this as a service when billions of concurrent users might be hitting, and thus log_hits would be called that often.

The second question was the following:

You are given a 7-digit phone number. You should find all possible letter combinations based on the digit-to-letter mapping on a numeric keypad and return only those that have a valid match against a given dictionary of words.