DoublyLL.java

class dNode{
    int val;
    dNode next;
    dNode prev;
    dNode(int val){
        this.val=val;
    }
}


public class DoublyLL {
    public static void print(dNode head){
        dNode temp=head;
        while(temp!=null){
            System.out.println(temp.val+" ");
            temp=temp.next;
        }
        System.out.println();
    }
    public static void printReverse(dNode tail){
        dNode temp=tail;
        while(temp!=null){
            System.out.println(temp.val+" ");
            temp=temp.prev;
        }
        System.out.println();
    }
    public static void display(dNode node){
        dNode temp=node;
        while(temp!=null && temp.prev!=null){
            temp=temp.next;
        }
        print(temp);
    }
    public static void main(String[] args) {
        dNode a=new dNode(10);
        dNode b=new dNode(20);
        dNode c=new dNode(30);
        dNode d=new dNode(40);
        a.next=b; b.prev=a;
        b.next=c; c.prev=b;
        c.next=d; d.prev=c;
        print(a);
        System.out.println(c.prev.val);
       // printReverse(d);
        display(b);
    }
}