In general , to minimise the number of swaps we use the selection sort bcoz everytime when we compare the elements of the array with the initial element we find the minimum element than the initial and do only one time swap it with the previous initial one.therefore the number of swaps is O(1) for every element and O(n) for n elements
whereas in merge sort there could be more than one swap at a time when we combine the two sorted arrays there could be possibility of getting more than one swap eg:{2,4,6} and {3,5,8}