Difference Between Quick Sort and Merge Sort

In this post, we will understand the difference between Quick Sort and Merge Sort.

Quick Sort

In Quick Sort, the elements need to be partitioned into different parts repeatedly until it can’t be divided further.
The array is split into a specific number of parts, in a specific ratio.
It is not divided necessarily into exactly half.
It is based on divide and conquer strategy.
It is also known as partition exchange sort.
The worst case complexity is O(n squared).
It uses a key/pivot element to sort elements.
It works well with small number of elements in an array.
It is better than other sorting algorithms since it is quick.
It requires less additional space/memory.
It doesn’t work well with large number of elements in an array.
It is not considered a stable sorting method.
It is considered as an internal sorting algorithm.

Merge Sort is considered as an external sorting algorithm.
The array is split into two sub-arrays (n/2) where ‘n’ is the number of elements in the array.
This is done until only on element is left after splitting the array.
It is based on divide and conquer strategy.
Its worst case complexity is O(n Log n), where ‘n’ is the number of elements.
It works with any size of the array, be it small or large.
It uses additional storage, since it needs to sort the auxiliary array.
It uses three arrays, where two of them store two halves of the array and the third array stores the final sorted list.
It works well at a good speed on any data size.
It is considered to be efficient.
It is considered to be a stable sorting algorithm.

Published on 23-Mar-2021 07:40:04