Merge Sort vs Quick Sort presentation
- 1. Mergesort vs Quicksort In Depth Analysis Presented By Maharaj Dey 11500117099 and Sandeep Kumar 11500117059
- 2. Why quicksort is better than mergesort ? This a common question asked in DS interviews that despite of better worst case performance of mergesort, quicksort is considered better than mergesort.
- 3. QuickSort
- 4. Merge Sort
- 5. Basis for comparison Quick Sort Merge Sort The partition of elements in the array The splitting of a array of elements is in any ratio, not necessarily divided into half. In the merge sort, the array is parted into just 2 halves (i.e. n/2). Worst case complexity O(n2) O(nlogn) Works well on It works well on smaller array It operates fine on any size of array Speed of execution It work faster than other sorting algorithms for small data set like Selection sort etc It has a consistent speed on any size of data Additional storage space requirement Less(In-place) More(not In-place) Efficiency Inefficient for larger arrays More efficient Sorting method Internal External Stability Not Stable Stable Preferred for for Arrays for Linked Lists Locality of reference good poor Comparison
- 6. There are certain reasons due to which quicksort is better especially in case of arrays: Auxiliary Space : Mergesort uses extra space, quicksort requires little space and exhibits good cache locality. Quick sort is an in-place sorting algorithm. In-place sorting means no additional storage space is needed to perform sorting. Merge sort requires a temporary array to merge the sorted arrays and hence it is not in-place giving Quick sort the advantage of space.rge sort. Locality of reference : Quicksort in particular exhibits good cache locality and this makes it faster than merge sort in many cases like in virtual memory environment. Worst Cases : The worst case of quicksort O(n2) can be avoided by using randomized quicksort. It can be easily avoided with high probability by choosing the right pivot. Obtaining an average case behavior by choosing right pivot element makes it improvise the performance and becoming as efficient as Merge sort. Merge sort is better for large data structures: Mergesort is a stable sort, unlike quicksort and heapsort, and can be easily adapted to operate on linked lists and very large lists stored on slow-to-access media such as disk storage or network attached storage.
- 7. Testcase Input: 25600 193 710 -326 -212 630 434 -378 728 25 702 -324 719 -546 -754 -256 -254 268 -718 -145 -28 12 125……… Program Code in Brief Outputs Results: