It wasn't me who downvoted. I can't (since you responded to me) and wouldn't have anyway. If you use last then that means the whole list will have to be sorted O(n log n ish) then the last element retrieved. And yes, I'm assuming a merge sort. But I still don't think that detracts too much from my point.
But it depends on the sort algorithm. In the exercise I did this on (in Ocaml with some custom lazy code, since Ocaml's wasn't lazy enough for what I was doing) I did sort in descending order.
