Merge Sort Time and Space Complexity

Question

Let\'s take this implementation of Merge Sort as an example

void mergesort(Item a[], int l, int r) {
if (r <= l) return;
int m = (r+l)/2;
mergesort(a, l,          


        

Answer 1

merge sort space complexity is O(nlogn), this is quite obvious considering that it can go to at maximum of O(logn) recursions and for each recursion there is additional space of O(n) for storing the merged array that needs to be reassigned. For those who are saying O(n) please don't forget that it is O(n) for reach stack frame depth.