Selection by sorting

Items in a list may undergo statistical inquiries such as finding the mean, median, and mode values. Finding the mean and mode values does not require the list to be ordered. However, to find the median in a list of numbers, the list must first be ordered. Finding the median requires you to find the element in the middle position of the ordered list. In addition, this can be used when we want to find the k^th smallest item in the list. To find the k^th smallest number in an unordered list of items, an obvious method is to first sort the list, and after sorting, you can rest assured that the element at index 0 will hold the smallest element in the list. Likewise, the last element in the list will hold the largest element in the list.

For more information on how to order data items within a list, see Chapter 11, Sorting. However, in order to obtain a k^th smallest element from the list, it is not a good solution to apply a sorting algorithm to a long list of elements...