1. Recitation 5 CS0445 Data Structures
Mehmud Abliz

2. Program Assignment 3
A deque (short for double-ended queue) is a data structure for which elements can be added to or removed from the front or back.

3. Program Assignment 3 The DequeInterface is shown below:
public interface DequeInterface {
public void addToFront(Object newEntry);
public void addToBack(Object newEntry);
public Object removeFront();
public Object removeBack();
public Object getFront();
public Object getBack();
public boolean isEmpty();
public void clear();
public void display(); }

4. Program Assignment 3
Suppose we start with an empty Deque d. In each line below, d is shown after the operation has been performed.
d.addToFront(“Jim”); // [“Jim”]
d.addToBack(“Jess”); // [“Jim”, “Jess”]
d.addToFront(“Jill”); // [“Jill”, “Jim”, “Jess”]
d.addToBack(“Jane”); // [“Jill”, “Jim”, “Jess”, “Jane”]
String s = d.getFront();
d.addToBack(s); // [“Jill”, “Jim”, “Jess”, “Jane”, “Jill”]
d.removeFront(); // [“Jim”, “Jess”, “Jane”, “Jill”]
d.addToFront(d.removeBack());// [“Jill”, “Jim”, “Jess”, “Jane”]

5. Your task
1. Your task is to implement the class LinkedDeque which implements the DequeInterface as a singly-linked list (see LList). The instance variables are shown below.
public class LinkedDeque implements DequeInterface{
private Node firstNode;
private Node lastNode;
private int length; }

6. Your task
2. In addition, you will implement an iterator for the LinkedDeque class by implementing a private inner class similar to what is done on pages for LLists. The class will be called IteratorForLinkedDeque and will implement the IteratorInterface (page 155).

7. Example public class LinkedDeque implements DequeInterface {
private Node firstNode;
private Node lastNode;
private int length;
// <Implementation of the constructor and methods of LinkedDeque go here>
// ...
public IteratorInterface getListIterator()
return new IteratorForLinkedDeque(); }
private class IteratorForLinkedDeque implements IteratorInterface

8. Example { private Node currentNode; private Node priorNode;
public IteratorForLinkedDeque()
currentNode = firstNode;
priorNode = null; }
// implementation of the methods in IteratorInterface go here
// ...
private class Node
// implementation of Node class goes here