The task is not to find an object in a hash tables. It's to nub an array into a set. Which is why we're not handwaving away the construction cost or ignoring k

The task is not to find an object in a hash tables. It's to nub an array into a set. Which is why we're not handwaving away the construction cost or ignoring key comparisons or other such thinking. Saying, "A hash tables solves this" is the definition of noise, because if you have a perfect hash function for a data set to get the constants you want then you've already got the solution to the problem presented for discussion here. The hash tables itself just becomes cargo culting.