Three-hour-long interviews, one after the other.

The interviews were all technical, with coding and similar tasks, but with three different people.

The questions were very focused on data structures. You are given a problem/task and have to comment which structure you want to use for it and implement it.

Even though the structures were some "simpler" ones like queues and hash maps, it included recognizing, commenting, and explaining modifications to them so you can adapt their functionalities, like priority queues and linked hash maps.

There are operations that can be committed to a bank account. Those operations are queued in some way until you use a commit function that performs them.

Explain how you would implement this, which structures you would use, and then code it.