[riffraff]

quicksort, e.g. the haskell[0] example is quite well known. Problem is, it's not real since it doesn't work in place defeating the whole point.

[0] https://qnikst.github.io/posts/2020-10-18-quicksort.html

[notpushkin]

It really shines if you want a shortcut on a whiteboard interview, though.