Final answer:
In the worst-case scenario, selection sort will perform about n^2 operations for a list of n items, which includes comparisons and swaps.
The algorithm repeatedly finds the minimum element from the unsorted section and moves it to the beginning, totaling roughly n^2 / 2 - n / 2 comparisons.
Step-by-step explanation:
If a list has n items, in the worst possible situation, selection sort will perform n2 / 2 - n / 2 comparisons to sort the items. Selection sort is a simple comparison-based sorting algorithm.
It works by repeatedly finding the minimum element from the unsorted part of the list and moving it to the beginning. This procedure is repeated for all the elements in the list.
The algorithm does n - 1 comparisons for the first element, n - 2 for the second element, and so on, until only one element is left. Therefore, the total number of comparisons in the worst-case scenario is given by the sum of the first n - 1 natural numbers, which can be accounted for with the formula (n2 - n) / 2.
Since the number of swaps in selection sort is exactly n - 1 in the worst case (one for each element except the last one), the complexity is dominated by the comparisons.
Therefore, in terms of operations, both comparisons and swaps must be counted, coming to roughly n2 operations in the worst-case scenario, where n is the number of items in the list.