The smoothsort sorting algorithm is a variation of heapsort developed by Edsger Dijkstra in 1981. The advantage of smoothsort is that it works in O(n) time if the input is (almost) sorted. Due to the extra complexity it is rarely used.

References

• A PDF of Dijkstra's original paper on Smoothsort (http://www.cs.utexas.edu/users/EWD/ewd07xx/EWD796a.PDF)