Explanation : If there are n elements, then in worst case, total
swaps will be (n-1) in selection sort. So the number
of swaps is Θ(n).
Alternately
The selection sort is similar to bubble sort except
it does not swap elements with every move. The
sorting algorithm first finds the smallest element
in the list and then puts it in to place in single
swap. So n swap required for n elements.