[saretired]

Sedgewick did animations of quicksort and other algorithms back in the 80's. He coincidentally did his PhD on quicksort under Knuth. Jon Bentley gave a Google Talk about quicksort and inputs that drive it to O(n^2) https://www.youtube.com/watch?v=QvgYAQzg1z8 His implementation of a production quicksort with McIroy is widely used. It's in BSD, glibc (non-recursive version--some here are saying that glibc qsort is a mergesort, but at least in the code I've read that's not true. Perhaps there's some confusion over the memory allocated by glibc qsort for the pointer stack it creates to avoid recursion). The paper by Bentley and McIlroy called ``Engineering a quicksort'' fills in many details that Bentley omits in his Google Talk.