Recalling the Bucketsort of Lecture 12
and the pipelined sorting method of Lecture 16,
we started off analyzing Mergesort, an analysis which will help
us when considering Quicksort.
One sorting algorithm we would normally not consider is Ranksort
because it needs O(n^2) operations. But with n processors,
it is straightforward to obtain an O(n) algorithm and with n^2
processors we can sort a sequence of n numbers in O(log(n))
operations, using the parallel summation algorithm.
The analysis of Quicksort shows that Quicksort is better than
Mergesort, but the performance of Quicksort depends critically
on the choice of the pivot. Therefore, we introduced the idea
of Samplesort, ending the lecture with a sketch of a parallel
implementation.
Bibliography