Quick sort is a comparison based sorting algorithm that follows the divide and conquer technique to sort the arrays. In quick sort, we usually use a pivot (key) element to compare and interchange the position of the element based on some condition. Merge sort is a most important sorting techniques that work on the divide and conquer strategies. It is the most popular sorting techniques used to sort data that is externally available in a file.
Differences between Quick Sort and Merge Sort are stated below
| Parameter | Quick Sort | Merge Sort |
|---|---|---|
| Definition | It is a quick sort algorithm that arranges the given elements into ascending order by comparing and interchanging the position of the elements. | It is a merge sort algorithm that arranges the given sets of elements in ascending order using the divide and conquer technique, and then compare with corresponding elements to sort the array. |
| Principle | It works on divide and conquer techniques. | It works on divide and conquer techniques. |
| Partition of elements | In quick sort, the array can be divide into any ratio. | Merge sort partition an array into two sub array (N/2). |
| Efficiency | It is more efficient and work faster in smaller size array, as compared to the merge sort. | It is more efficient and work faster in larger data sets or array, as compare to the quick sort. |
| Sorting method | It is an internal sorting method that sort the array or data available on main memory. | It is an external sorting method that sort the array or data sets available on external file. |
| Time complexity | Its worst time complexity is O (n2). | Whereas, it’s worst time complexity is O (n log n). |
| Preferred | It is a sorting algorithm that is applicable for large unsorted arrays. | Whereas, the merge sort algorithm that is preferred to sort the linked lists. |
| Stability | Quick sort is an unstable sort algorithm. But we can made it stable by using some changes in programming code. | Merge sort is a stable sort algorithm that contains two equal elements with same values in sorted output. |
| Requires Space | It does not require any additional space to perform the quick sort. | It requires the additional space as temporary array to merge two sub arrays. |
| Functionality | Compare each element with the pivot until all elements are arranged in ascending order. | Whereas, the merge sort splits the array into two parts (N/2) and it continuously divides the array until an element is left. |