Each of n keys in an array may have one of the values red, white, or blue. Give an efficient algorithm for rearranging the keys so that all the reds come before all the whites, and all the whites come before all the blues. (It may happen that there are no keys of one or two of the colors.) The only operations that are permitted on the keys are examination of a key to find out what color it is, and an exchange of two keys (specified by their indices). How many key examinations and exchanges does your algorithm perform in the worst case