HERE THE ANALYSIS-ALL ARE COMPARISON BASED SORTING ....BEST CASE is n*logn...
here its strict reverse order.
1.INSERTION SORT- would take O(n^2)...swapping the element take n^2 times .
2.QUICK sort - take here O(n^2)...due to unbalanced tree form at each step.tree would have height n with n(n-1)/2 comparisons in total
3 .HEAP sort - take always O(n*logn){balancing tree take logn and it happens for n elements}
4.MERGE sort - take here O(n/2*logn) at each level n/2 comparisons ...and its done for logn height of tree....
SO BEST HERE IS MERGE SORT