One of the most frequently posed linked list Interview Questions, be ready for it. In the case of Arrays, if you use a Quick Sort, you generally don’t require any supplementary space for storing, but if you choose a merge sort, it will cost you an extra O(N) space for storage, where N is the length of the array so it will be quite expensive for you. This, in turn, will increase the running time of the algorithm. But if you compare the average time complexity for both the sorts, you have O(NlogN) average time complexity, which will be approximately the same for both, but the constants you will get are not the same. So, for arrays, merge sort is not optimal due to the usage of extra storage of O(N).  In the case of a Linked List, all elements are not at adjacent positions like arrays, and you can insert an element at any place in it in O(1) space and time if you are given the reference and hence for even a merge sort you won’t be needing any extra space. As arrays have elements at contiguous positions, you can access any memory location, whereas in the linked list, you cannot for a quick sort algorithm, you need a lot of such movements, and for that, you have to move along all the elements in the list which increases the load, Whereas in merge sort it is much optimal hence you will prefer it.