Replying to
@Catfish_Man I agree the interview structure isn't the right one, but there's something to be said for picking the right data structure in the first place, so that you don't have to wait for the natural pushback later. 80% of the time it won't matter, and 5% of the time it might make things worse, but I think there's still a good 15% or so where having better defaults than "accidentally quadratic" is worth being part of the initial implementation.