Selection sorting refers to a class of algorithms for sorting a list of items using comparisons. These algorithms select successively smaller or larger items from the list and add them to the output sequence. This is an improvement of the Simple Selection Sort and instead of replacing the selected element by a unique value in the i-th pass (as happens in Simple Selection Sort), the selected element is exchanged with the i-th element. Let’s assume an array “a” with “n” elements. Thus, at the beginning of the i-th pass, the first (i-1) elements of the array are those that have been selected in the previous passes. The smallest element is now searched in the remaining (n-i+1) elements. After (n-1) passes, the sorted array is completely developed in the space occupied by the original array.
The simplest possible technique based on the principle of repeated selection makes use of “n” passes over an array elements. In the i-th pass, the i-th smallest element is selected from the given array and it is placed in the i-th position of a separate output array. The already selected element is not selected next time and in order to ensure it, a unique value is put in place of the selected element in the original array.