Overview

Insertion sort is a great algorithm, because it’s very intuitive and it is easy to implement, but the problem is that it makes many exchanges for each “light” element in order to put it on the right place. Thus “light” elements at the end of the list may slow down the performance of insertion sort a lot. That is why in 1959 Donald Shell proposed an algorithm that tries to overcome this problem by comparing items of the list that lie far apart.

In the other hand it is obvious that by comparing items that lie apart the list can’t be sorted in one pass as insertion sort. That is why on each pass we should use a fixed gap between the items, then decrease the value on every consecutive iteration. Continue reading Computer Algorithms: Shell Sort →