Doubly linked circular list.java

// Java program to illustrate inserting a Node in
// a Circular Doubly Linked list in begging, end
// and middle
import java.util.*;
 
class GFG
{
 
static Node start;
 
// Structure of a Node
static class Node
{
    int data;
    Node next;
    Node prev;
};
 
// Function to insert at the end
static void insertEnd(int value)
{
    // If the list is empty, create a single node
    // circular and doubly list
    if (start == null)
    {
        Node new_node = new Node();
        new_node.data = value;
        new_node.next = new_node.prev = new_node;
        start = new_node;
        return;
    }
 
    // If list is not empty
 
    /* Find last node */
    Node last = (start).prev;
 
    // Create Node dynamically
    Node new_node = new Node();
    new_node.data = value;
 
    // Start is going to be next of new_node
    new_node.next = start;
 
    // Make new node previous of start
    (start).prev = new_node;
 
    // Make last previous of new node
    new_node.prev = last;
 
    // Make new node next of old last
    last.next = new_node;
}
 
// Function to insert Node at the beginning
// of the List,
static void insertBegin(int value)
{
    // Pointer points to last Node
    Node last = (start).prev;
 
    Node new_node = new Node();
    new_node.data = value; // Inserting the data
 
    // setting up previous and next of new node
    new_node.next = start;
    new_node.prev = last;
 
    // Update next and previous pointers of start
    // and last.
    last.next = (start).prev = new_node;
 
    // Update start pointer
    start = new_node;
}
 
// Function to insert node with value as value1.
// The new node is inserted after the node with
// with value2
static void insertAfter(int value1,
                                    int value2)
{
    Node new_node = new Node();
    new_node.data = value1; // Inserting the data
 
    // Find node having value2 and next node of it
    Node temp = start;
    while (temp.data != value2)
        temp = temp.next;
    Node next = temp.next;
 
    // insert new_node between temp and next.
    temp.next = new_node;
    new_node.prev = temp;
    new_node.next = next;
    next.prev = new_node;
}
 
static void display()
{
    Node temp = start;
 
    System.out.printf("\nTraversal in forward direction \n");
    while (temp.next != start)
    {
        System.out.printf("%d ", temp.data);
        temp = temp.next;
    }
    System.out.printf("%d ", temp.data);
 
    System.out.printf("\nTraversal in reverse direction \n");
    Node last = start.prev;
    temp = last;
    while (temp.prev != last)
    {
        System.out.printf("%d ", temp.data);
        temp = temp.prev;
    }
    System.out.printf("%d ", temp.data);
}
 
/* Driver code*/
public static void main(String[] args)
{
    /* Start with the empty list */
    Node start = null;
 
    // Insert 5. So linked list becomes 5.null
    insertEnd(5);
 
    // Insert 4 at the beginning. So linked
    // list becomes 4.5
    insertBegin(4);
 
    // Insert 7 at the end. So linked list
    // becomes 4.5.7
    insertEnd(7);
 
    // Insert 8 at the end. So linked list
    // becomes 4.5.7.8
    insertEnd(8);
 
    // Insert 6, after 5. So linked list
    // becomes 4.5.6.7.8
    insertAfter(6, 5);
 
    System.out.printf("Created circular doubly linked list is: ");
    display();
}
}