Below is the UML class diagram for the Stack class (storing Integers) provided in the lectures by the instructor. The dup() method is supposed to duplicate the top item on the stack. For example, Stack s = new Stack(); s.push(1); // s contains 1 s.push(2); // s contains 2, 1 s.push(3); // s contains 3, 2, 1 s.dup(); // s contains 3, 3, 2, 1 Implement dup(). You may assume that dup() will not be called on an empty stack.

2)

Continuing. The rot() method performs a "rotation" of the top three items the stack. For example,

 Stack s = new Stack(); s.push(1); // s contains 1 s.push(2); // s contains 2, 1 s.push(3); // s contains 3, 2, 1 s.push(4); // s contains 4, 3, 2, 1 s.rot(); // s contains 3, 2, 4, 1 

That is, after a rotation, the top item on the stack is the item that was below the top item, the second item is the item that was below the second item, and the third item is the item that was previously on top of the stack. For this question, implement rot(). You may assume that rot() will not be called on a stack with fewer than three elements.

DList Stack mList: DList + Stack): ctor +clear0: void +dup): void +isEmpty): boolear +peek): Integer +pop0: Integer +push(pD ata: Integer): void +rot): void +toString): String override #getLi st(): DList #setList(pList DList): void