# Quick Sort vs Merge Sort

Posted September 12, 2022 by Rohith and Anusha ‐ 2 min read

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

ParameterQuick SortMerge Sort
DefinitionIt 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.
PrincipleIt works on divide and conquer techniques.It works on divide and conquer techniques.
Partition of elementsIn quick sort, the array can be divide into any ratio.Merge sort partition an array into two sub array (N/2).
EfficiencyIt 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 methodIt 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 complexityIts worst time complexity is O (n2).Whereas, it’s worst time complexity is O (n log n).
PreferredIt is a sorting algorithm that is applicable for large unsorted arrays.Whereas, the merge sort algorithm that is preferred to sort the linked lists.
StabilityQuick 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 SpaceIt does not require any additional space to perform the quick sort.It requires the additional space as temporary array to merge two sub arrays.
FunctionalityCompare 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.