Question

public class DoublyLinkedList {
    Node Head; // head of Doubly Linked List

    //Doubly Linked list Node
    class Node {
        int value;
        Node prev;
        Node next;

        // Constructor to create a new node







        Node(int d) { value = d; }
    }

    // Inserting a node at the front of the list
    public void add(int newData)
    {
        // allocate node and put in the data
        Node newNode = new Node(newData);

        // Make the next of new node as head
        // and previous as NULL
        newNode.next = Head;
        newNode.prev = null;

        //change prev of head node to the new node
        if (Head != null)
            Head.prev = newNode;

        //move the head to point to the new node
        Head = newNode;
    }

    // Function to delete a node in a Doubly Linked List.
    void remove(Node del)
    {

        // Base case
        if (Head == null || del == null) {
            return;
        }

        // If node to be deleted is head node
        if (Head == del) {
            Head = del.next;
        }

        // When node to be deleted is not
        // the last node, change next.
        if (del.next != null) {
            del.next.prev = del.prev;
        }

        // When node to be removed is not the first node,
        // change prev.
        if (del.prev != null) {
            del.prev.next = del.next;
        }

        return;
    }
    //Function to display Doubly Linked List content
    public void display(Node node)
    {
        Node last = null;

        while (node != null) {
            System.out.print(node.value + " ");
            last = node;
            node = node.next;
        }

        System.out.println();
    }



    public static void main(String[] args)
    {
        // Initiallize the Doubly Linked List
        DoublyLinkedList d = new DoublyLinkedList();

        // add 6.
        d.add(6);

        // add 19.
        d.add(19);

        // add 2.
        d.add(2);

        // add 15.
        d.add(15);

        System.out.print("Doubly Linked List ");
        d.display(d.Head);

        // Removing first node
        d.remove(d.Head);

        // List after removing first node
        // 2->19->6
        System.out.print("\nDoubly Linked List after removing first node: ");
        d.display(d.Head);

        // Removing middle node from 2->19->6
        d.remove(d.Head.next);

        System.out.print("\nDoubly Linked List after removing middle node: ");
        d.display(d.Head);
    }
}

WRITE THE UML DIAGRAM AND PSEUDO CODE

Answer 1

The UML Class diagram is:

The pseudocode is given as:

Pseudocode

Each Node of the doubly linked list consists of the data value, a pointer pointing to the previous element and a next pointer pointing to the next element.

// add method inserts a node at the front of the list

function add (newData) {

newNode = Node(newData); // create a new node with the given data

newNode.next = Head

newNode.prev = null

if Head is not null then

Head.prev = newNode

end if

Head = newNode

}

// this function deletes a node in a Doubly Linked List.

function remove(del){

if (Head is null or del is null) then

return

end if

if Head is same as del) then

Head = del.next

end if

if (del.next is not null) then

del.next.prev = del.prev

end if

if (del.prev is not null) then

del.prev.next = del.next

end if

}

// display() displays Doubly Linked List content

function display(node) {

last = null

run till (node is not null) do

print node.value

last = node

node = node.next

end loop   

}

System.out.println();

}