Given a doubly linked list (code provided to you in the lecture note) implement
ID: 3694527 • Letter: G
Question
Given a doubly linked list (code provided to you in the lecture note) implement a Stack and a Queue. You must use the doubly link list class and utilize it as an object in your implementation of the stack and queue. You may edit it and you may also modify it but you must include it as part of your implementation.
Implement a Stack
A Stack is a Last in First Out (LiFO) structure which translates to the processes of outputting the last element which was inputted in the collection. The Stack is based on the process of putting things on top of one another and taking the item on top (think of a stack of papers).
Operations to implement:
push (E): Add an element to the start of the sequence
pop: Remove an element from the start of the sequence
Peek: Return the first element of the sequence without removing it
atIndex(x): Return the element at the given index (x) Or throw an exception if it is out of bound (if you can control the user input then do that instead)
Size: Return the size of the Stack
isEmpty: Boolean, returns true if the Stack is empty
Empty: Empty the Stack
Implement a Queue
A Queue is a First in First Out (FiFO) structure which translates to the processes of outputting the first item inputted into a collection. The Queue is based on the process of waiting in line to get serviced (bank or six flags), where those who arrive first get serviced first.
Operations to implement:
Enqueue/push (E): Add an element to the end of the sequence
Dequeue/pop: Remove an element from the start of the sequence
Front/Peek: Return the first element of the sequence without removing it (what the head is pointing to)
atIndex(x): Return the element at the given index (x) Or throw an exception if it is out of bound (if you can control the user input then do that instead)
Size: Return the size of the Queue
isEmpty: Boolean, returns true if the Queue is empty
Empty: Empty the Queue
Back: Return what the tail is pointing to
DNode.java
public class DNode
{
private Object e; // place holder for the type of object the
//collection is storing
private DNode next; // reference to the next node in the sequence
// of nodes making up the linked list. Remember
// that even though Java passes Objects by value
// an object consisting of reference will behave
// the same as an object passed by reference unless
// a deep copy was made.
private DNode prev;
public DNode (Object e) // Constructor for implementing a single node
{
this.e = e; // The value of the element to be assigned to
// this particular instance of node
this.next = null; // An empty reference since there is no node
// to follow.
this.prev = null;
}
public DNode (Object e, DNode next, DNode prev) // Constructor for implementing a
// node that comes after another
// node
{
this.e = e; // The value of the element to be assigned to
// this particular instance of node
this.next = next; // reference to the subsequent node to follow
this.prev = prev;
}
public void changeNext (DNode next) // Changes the link to the next node
{
this.next = next;
}
public void changePrev (DNode prev) // Changes the link to the next node
{
this.prev = prev;
}
public DNode getNext() // Returns the node next in the sequence
{
return this.next;
}
public Object getValue() // Returns the value a node is holding
{
return this.e;
}
public Boolean hasNext() // Returns a boolean determining regarding
// the status of subsequent nodes after
// the current node
{
return !(this.next.getValue() == null || this.next == null);
}
public Boolean hasprev() // Returns a boolean determining regarding
// the status of subsequent nodes after
// the current node
{
return !(this.prev.getValue() == null || this.prev == null);
}
public void insertAfterNode( Object input)
{
this.changeNext(new DNode (input, this.getNext(), this));
}
public void insertAfterNode (DNode input)
{
this.changeNext(input);
input.changeNext(this.next);
input.changePrev(this);
}
public void insertbeforeNode (DNode input)
{
this.changeNext(input);
}
public void insertBetweenNodes(DNode before, DNode after)
{
this.changeNext(after);
this.changePrev(before);
before.changeNext(this);
after.changePrev(this);
}
public DNode getPrev()
{
return this.prev;
}
}
DoublyLinkedList.java
public class DoublyLinkedList
{
private DNode head;
private DNode tail;
private int size;
public DoublyLinkedList () // construct an empty list
{
this.tail = new DNode (null, null, this.head);
this.head = new DNode (null, this.tail, null);
this.size = 0;
}
public DoublyLinkedList (DNode next) // constructs a list
// out of a single node
{
this.tail = new DNode (null, null, next);
this.head = new DNode (null, next, null);
next.changeNext(this.tail);
next.changePrev(this.head);
this.size = 1;
}
public DoublyLinkedList(Object [] objectArray) // construct a list out of
// an array
{
this.tail = new DNode (null, null, this.head);
this.head = new DNode (null, this.tail, null);
DNode temp = this.head;
for (Object e : objectArray)
{
//Anonomus function
new DNode (e, temp.getNext(),temp).insertBetweenNodes(temp, temp.getNext());
temp = temp.getNext();
this.size += 1;
}
}
public void addToFrontofList (Object toAdd) // Appends the begining
// of the list
{
DNode temp = new DNode (toAdd, this.head.getNext(), this.head);
this.head.getNext().changePrev(temp);
this.head.changeNext(temp);
this.size += 1;
}
public void addToendofList (Object toAdd) // appends the end of the list
// with a node
{
DNode temp = new DNode (toAdd, this.tail, this.tail.getPrev());
this.tail.getPrev().changeNext(temp);
this.tail.changePrev(temp);
this.size += 1;
}
public void insertAfterNode(DNode current, Object input)// Inserts a new
// a new node after
// current node
{
current.insertAfterNode(input);
this.size += 1;
}
public int getSize() // returns the size of the list
{
return this.size;
}
@Override
public String toString()
{
String result = "";
for (DNode temp = this.head.getNext(); temp.hasNext(); temp = temp.getNext())
{
result += temp.getValue();
result += " -> ";
}
result += "End of list";
return result;
}
}
Explanation / Answer
program :
class LinkedListEmptyException extends RuntimeException
{
public LinkedListEmptyException()
{
super();
}
public LinkedListEmptyException(String message)
{
super(message);
}
}
class StackEmptyException extends RuntimeException
{
public StackEmptyException()
{
super();
}
public StackEmptyException(String message)
{
super(message);
}
}
class Node
{
public int data;
public Node next;
public Node(int data)
{
this.data = data;
}
public void displayNode()
{
System.out.print( data + " ");
}
}
class LinkedList
{
private Node first;
public LinkedList()
{
first = null;
}
public void insertFirst(int data)
{
Node newNode = new Node(data);
newNode.next = first;
first = newNode;
}
public Node deleteFirst()
{
if(first==null){ //means LinkedList in empty, throw exception.
throw new LinkedListEmptyException("LinkedList doesn't contain any Nodes.");
}
Node tempNode = first; // save reference to first Node in tempNode- so that we could return saved reference.
first = first.next; // delete first Node (make first point to second node)
return tempNode; // return tempNode (i.e. deleted Node)
}
public void displayLinkedList()
{
Node tempDisplay = first;
while (tempDisplay != null)
{
tempDisplay.displayNode();
tempDisplay = tempDisplay.next;
}
System.out.println();
}
}
class StackLinkedList
{
LinkedList linkedList = new LinkedList();
public void push(int value)
{
linkedList.insertFirst(value);
}
public void pop() throws StackEmptyException
{
try
{
linkedList.deleteFirst();
}
catch(LinkedListEmptyException llee)
{
throw new StackEmptyException();
}
}
public void displayStack()
{
System.out.print("Displaying Stack > Top to Bottom : ");
linkedList.displayLinkedList();
}
}
public class StackImplementationUsingLinkedListExample
{
public static void main(String[] args)
{
StackLinkedList stackLinkedList=new StackLinkedList();
System.out.println("INSERTING AT FIRST (TOP) IN STACK IMPLEMENTED USING LINKED LIST ");
stackLinkedList.push(39); //push node.
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
stackLinkedList.push(71); //push node.
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
stackLinkedList.push(11); //push node.
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
stackLinkedList.push(76); //push node.
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
System.out.println(" DELETING FROM FIRST (TOP) FROM STACK IMPLEMENTED USING LINKED LIST ");
stackLinkedList.pop(); //pop Node
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
stackLinkedList.pop(); //pop Node
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
stackLinkedList.pop(); //pop Node
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
stackLinkedList.pop(); //pop Node
stackLinkedList.displayStack(); // display STACK IMPLEMENTED USING LINKED LIST in java
}
}
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