Doubly linked list Insertion at given position GFG Problem

 Input: head = [5,2,13,3,8]

Output: [13,8]

Explanation: The nodes that should be removed are 5, 2 and 3.

- Node 13 is to the right of node 5.

- Node 13 is to the right of node 2.

- Node 8 is to the right of node 3.

Example 2:


Input: head = [1,1,1,1]

Output: [1,1,1,1]

Explanation: Every node has value 1, so no nodes are removed.Given a doubly-linked list, a position p, and an integer x. The task is to add a new node with value x at the position just after pth node in the doubly linked list and return the head of the updated list.


Examples:


Input: LinkedList: 2<->4<->5, p = 2, x = 6 

Output: 2<->4<->5<->6

Explanation: p = 2, and x = 6. So, 6 is inserted after p, i.e, at position 2 (0-based indexing).

Input: LinkedList: 1<->2<->3<->4, p = 0, x = 44

Output: 1<->44<->2<->3<->4

Explanation: p = 0, and x = 44 . So, 44 is inserted after p, i.e, at position 0 (0-based indexing).



//{ Driver Code Starts

import java.io.*;

import java.util.*;


class Node {

    int data;

    Node next;

    Node prev;


    Node(int data) {

        this.data = data;

        next = prev = null;

    }

}


class DLinkedList {


    Node newNode(Node head, int data) {

        Node n = new Node(data);

        if (head == null) {

            head = n;

            return head;

        }

        head.next = n;

        n.prev = head;

        head = n;

        return head;

    }


    void printList(Node node) {

        Node temp = node;

        while (temp.next != null) {

            temp = temp.next;

        }


        while (temp.prev != null) {

            temp = temp.prev;

        }


        while (temp != null) {

            System.out.print(temp.data + " ");

            temp = temp.next;

        }

        System.out.println();

    }


    public static void main(String args[]) throws IOException {


        DLinkedList DLL = new DLinkedList();

        BufferedReader read = new BufferedReader(new InputStreamReader(System.in));

        int t = Integer.parseInt(read.readLine());


        while (t > 0) {

            Node temp;

            Node head = null;

            Node root = null;

            String str[] = read.readLine().trim().split(" ");

            int n = str.length;


            for (int i = 0; i < n; i++) {

                int x = Integer.parseInt(str[i]);

                head = DLL.newNode(head, x);

                if (root == null) root = head;

            }

            head = root;


            String str2[] = read.readLine().trim().split(" ");

            int pos = Integer.parseInt(str2[0]);

            int data = Integer.parseInt(str2[1]);


            Solution g = new Solution();

            head = g.addNode(head, pos, data);


            DLL.printList(head);

            while (head.next != null) {

                temp = head;

                head = head.next;

            }

            t--;

            System.out.println("~");

        }

    }

}

// } Driver Code Ends



/* Structure of Doubly Linked List

class Node

{

    int data;

    Node next;

    Node prev;

    Node(int data)

    {

        this.data = data;

        next = prev = null;

    }

}*/


class Solution {

    // Function to insert a new node at given position in doubly linked list.

    Node addNode(Node head, int p, int x) {

        // Your code here

         Node newnode = new Node(x);

        Node temp = head;


        // Traverse to (p)-th node

        for (int i = 0; i < p; i++) {

            if (temp == null) return head; // If position is out of bounds

            temp = temp.next;

        }


        // Inserting newnode after 'temp'

        newnode.next = temp.next;

        newnode.prev = temp;

        

        if (temp.next != null) {

            temp.next.prev = newnode; // Avoid NullPointerException

        }

        temp.next = newnode;


        return head;

    }

}

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