I was thinking some simple structure to deal with repeated values when I saw the 10k / a million are different than, but I feel the person you are replying too

I was thinking some simple structure to deal with repeated values when I saw the 10k / a million are different than, but I feel the person you are replying too is making a universal point that so many interviewers are convinced their problem is obvious and any decent dev should do it "their way". The data struct also should come with some use case about it, what else is it doing than 'storing' and enumerating results.