Question

Write a pseudocode method swap(aList, i, j) that interchanges the items currently in positions i and j of a list. Define the method in terms of the operations of the ADT list, so that it is independent of any particular implementation of the list. Assume that the list, in fact, has items at positions i and j. What impact does this assumption have on your solution

Answer 1

Answer:

Explanation:

The following pseudocode for this method using operations of the ADT list would be the following

swap(aList, indexI, indexJ) {

    initialize temp_variable = Retrieve(indexI, aList)

    Insert(Retrieve(indexJ, aList), indexI, aList)

    Insert(Retrieve(indexI, aList), temp_variable, aList)

}

This code basically saves the aList index of i , into a temporary Variable. Then it sets the aList index of i to the value of the element in index of j. Then it does the same for the index of j with the tem_variable. If we assume that the indexes of i and j exist, then it can crash our entire program if those indexes are missing from the list when we try to access them.