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Java Program For Pointing Arbit Pointer To Greatest Value Right Side Node In A Linked List

  • Last Updated : 30 Dec, 2021

Given singly linked list with every node having an additional “arbitrary” pointer that currently points to NULL. We need to make the “arbitrary” pointer to the greatest value node in a linked list on its right side.
 

listwithArbit1

A Simple Solution is to traverse all nodes one by one. For every node, find the node which has the greatest value on the right side and change the next pointer. The Time Complexity of this solution is O(n2).

An Efficient Solution can work in O(n) time. Below are the steps.  

  1. Reverse the given linked list.
  2. Start traversing the linked list and store the maximum value node encountered so far. Make arbit of every node to point to max. If the data in the current node is more than the max node so far, update max.
  3. Reverse modified linked list and return head.

Following is the implementation of the above steps.  

Java




// Java program to point arbit pointers 
// to highest value on its right 
class GfG{ 
  
// Link list node 
static class Node 
    int data; 
    Node next, arbit; 
}
  
/* Function to reverse the 
   linked list */
static Node reverse(Node head) 
    Node prev = null
         current = head, next = null
    while (current != null
    
        next = current.next; 
        current.next = prev; 
        prev = current; 
        current = next; 
    
    return prev; 
  
// This function populates arbit pointer 
// in every node to the greatest value 
// to its right. 
static Node populateArbit(Node head) 
    // Reverse given linked list 
    head = reverse(head); 
  
    // Initialize pointer to maximum 
    // value node 
    Node max = head; 
  
    // Traverse the reversed list 
    Node temp = head.next; 
    while (temp != null
    
        // Connect max through arbit 
        // pointer 
        temp.arbit = max; 
  
        // Update max if required 
        if (max.data < temp.data) 
            max = temp; 
  
        // Move ahead in reversed list 
        temp = temp.next; 
    
  
    // Reverse modified linked list 
    // and return head. 
    return reverse(head); 
  
// Utility function to print result 
// linked list 
static void printNextArbitPointers(Node node) 
    System.out.println("Node    " +
                       "Next Pointer    " +
                       "Arbit Pointer"); 
    while (node != null
    
        System.out.print(node.data + 
                         "        "); 
  
        if (node.next != null
            System.out.print(node.next.data + 
                             "        "); 
        else
            System.out.print("NULL" +
                             "        "); 
  
        if (node.arbit != null
            System.out.print(node.arbit.data); 
        else
            System.out.print("NULL"); 
  
        System.out.println(); 
        node = node.next; 
    
  
/* Function to create a new node 
   with given data */
static Node newNode(int data) 
    Node new_node = new Node(); 
    new_node.data = data; 
    new_node.next = null
    return new_node; 
  
// Driver code
public static void main(String[] args) 
    Node head = newNode(5); 
    head.next = newNode(10); 
    head.next.next = newNode(2); 
    head.next.next.next = newNode(3); 
  
    head = populateArbit(head); 
  
    System.out.println(
           "Resultant Linked List is: "); 
    printNextArbitPointers(head); 
}
// This code is contributed by Prerna Saini.

Output: 

Resultant Linked List is: 
Node    Next Pointer    Arbit Pointer
5               10              10
10              2               3
2               3               3
3               NULL            NULL

Recursive Solution: 
We can recursively reach the last node and traverse the linked list from the end. The recursive solution doesn’t require reversing the linked list. We can also use a stack in place of recursion to temporarily hold nodes. Thanks to Santosh Kumar Mishra for providing this solution. 

Java




// Java program to point arbit pointers 
// to highest value on its right
class GfG
{
    // Link list node 
    static class Node
    {
        int data;
        Node next, arbit;
    }
  
    static Node maxNode;
  
    // This function populates arbit pointer 
    // in every node to the greatest value 
    // to its right.
    static void populateArbit(Node head)
    {
        // if head is null simply return 
        // the list
        if (head == null)
            return;
  
        /* if head->next is null it means we 
           reached at the last node just update 
           the max and maxNode */
        if (head.next == null)
        {
            maxNode = head;
            return;
        }
  
        /* Calling the populateArbit to the 
           next node */
        populateArbit(head.next);
  
        /* updating the arbit node of the current
           node with the maximum value on the 
           right side */
        head.arbit = maxNode;
  
        /* if current Node value id greater then
           the previous right node then update it */
        if (head.data > maxNode.data)
            maxNode = head;
  
        return;
    }
  
    // Utility function to print result 
    // linked list
    static void printNextArbitPointers(Node node)
    {
        System.out.println("Node    "
                           "Next Pointer    "
                           "Arbit Pointer");
        while (node != null)
        {
            System.out.print(node.data + 
                             "            ");
  
            if (node.next != null)
                System.out.print(node.next.data + 
                                 "                ");
            else
                System.out.print("NULL" +
                                 "            ");
  
            if (node.arbit != null)
                System.out.print(node.arbit.data);
            else
                System.out.print("NULL");
  
            System.out.println();
            node = node.next;
        }
    }
  
    /* Function to create a new node 
       with given data */
    static Node newNode(int data)
    {
        Node new_node = new Node();
        new_node.data = data;
        new_node.next = null;
        return new_node;
    }
  
    // Driver code
    public static void main(String[] args)
    {
        Node head = newNode(5);
        head.next = newNode(10);
        head.next.next = newNode(2);
        head.next.next.next = newNode(3);
  
        populateArbit(head);
  
        System.out.println(
               "Resultant Linked List is: ");
        printNextArbitPointers(head);
    }
}
// This code is contributed by shubham96301    

Output: 

Resultant Linked List is: 
Node    Next Pointer    Arbit Pointer
5               10              10
10              2               3
2               3               3
3               NULL            NULL

Please refer complete article on Point arbit pointer to greatest value right side node in a linked list for more details!


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