Question

Const int MAX=10;

class AList{
public :
AList();
void Retrieve(int k, &x, int bool &success);
\\retrieve the kth element and save it in x
void Delete(int k, int &x, bool &success);
\\ delete element at the position with index k and save it in x
void Insert(int k, int x, bool &success);
\\ insert element x at the position with index k
…
private :
int list[MAX];
int size;
};
AList aList;
1.With only the above methods, how do you implement the function swap (swap (aList, i, j) ) that interchanges the items currently in positions i and j of a list.

Answer 1

If you want to implement the swap function in the given code, you can use the Retrieve method to get the values of elements at positions i and j, and then use the Delete and Insert methods to swap the elements.

Step-by-step explanation:

To implement the swap () function that swaps the items currently in positions i and j of the AList, you can follow these steps:

1. Check if i and j are within the valid range of the list indices (0 to size-1). If either i or j is outside this range, the swap cannot be performed, so return without making any changes.

2. Retrieve the elements at positions i and j using the Retrieve () method. You will need two variables to store the retrieved elements, let's call them x and y.

3. Delete the elements at positions i and j using the Delete () method. This will remove the elements from the list and update its size accordingly. Make sure to check the success variable to ensure that the deletion was successful.

4. Now, use the Insert () method to insert the retrieved elements back into the list, but with their positions swapped. Use the Insert () method twice: first, insert element y at position i, and then insert element x at position j. Again, check the success variable to ensure the insertion was successful.

Here's an example code snippet that demonstrates the implementation of the swap () function:

```cpp

void swap (AList & list, int i, int j) {

int x, y;

bool success;

// Step 1: Check if i and j are within range

if (i < 0 || i >= list. size || j < 0 || j >= list.s ize) {

return;

}

// Step 2: Retrieve elements at positions i and j

list. Retrieve (i, x, success);

list. Retrieve (j, y, success);

// Step 3: Delete elements at positions i and j

list. Delete (i, x, success);

list. Delete (j, y, success);

// Step 4: Insert the retrieved elements back with swapped positions

list. Insert (i, y, success);

list. Insert (j, x, success);

}

```

In this code, we assume that the Retrieve (), Delete (), and Insert() methods of the AList class have been properly implemented to perform the required operations. The swap() function takes a reference to the AList object, the indices i and j, and follows the steps outlined above to swap the items at positions i and j.