Point arbit pointer to greatest value right side node in a linked list

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 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 greatest value on right side and change the next pointer. Time Complexity of this solution is O(n2).

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

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

Following is the implementation of above steps.

C++

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// C++ program to point arbit pointers to highest
// value on its right
#include<bits/stdc++.h>
using namespace std;
  
/* Link list node */
struct Node
{
    int data;
    Node* next, *arbit;
};
  
/* Function to reverse the linked list */
Node* reverse(Node *head)
{
    Node *prev = NULL, *current = head, *next;
    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.
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
void printNextArbitPointers(Node *node)
{
    printf("Node\tNext Pointer\tArbit Pointer\n");
    while (node!=NULL)
    {
        cout << node->data << "\t\t";
  
        if (node->next)
            cout << node->next->data << "\t\t";
        else cout << "NULL" << "\t\t";
  
        if (node->arbit)
            cout << node->arbit->data;
        else cout << "NULL";
  
        cout << endl;
        node = node->next;
    }
}
  
/* Function to create a new node with given data */
Node *newNode(int data)
{
    Node *new_node = new Node;
    new_node->data = data;
    new_node->next = NULL;
    return new_node;
}
  
/* Driver program to test above functions*/
int main()
{
    Node *head = newNode(5);
    head->next = newNode(10);
    head->next->next = newNode(2);
    head->next->next->next = newNode(3);
  
    head = populateArbit(head);
  
    printf("Resultant Linked List is: \n");
    printNextArbitPointers(head);
  
    return 0;
}

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Java

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// 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\tNext Pointer\tArbit Pointer"); 
    while (node != null
    
        System.out.print(node.data + "\t\t"); 
  
        if (node.next != null
            System.out.print(node.next.data + "\t\t"); 
        else
            System.out.print("NULL" +"\t\t"); 
  
        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.

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C#

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// C# program to point arbit pointers  
// to highest value on its right
using System;
  
class GfG 
  
    /* Link list node */
    class Node 
    
        public int data; 
        public 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) 
    
        Console.WriteLine("Node\tNext Pointer\tArbit Pointer"); 
        while (node != null
        
            Console.Write(node.data + "\t\t"); 
  
            if (node.next != null
                Console.Write(node.next.data + "\t\t"); 
            else
                Console.Write("NULL" +"\t\t"); 
  
            if (node.arbit != null
                Console.Write(node.arbit.data); 
            else
                Console.Write("NULL"); 
  
            Console.WriteLine(); 
            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); 
  
        Console.WriteLine("Resultant Linked List is: "); 
        printNextArbitPointers(head); 
    }
}
  
/* This code is contributed by 29AjayKumar */

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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 end. Recursive solution doesn’t require reversing of 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.

C++

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// C++ program to point arbit pointers to highest
// value on its right
#include<bits/stdc++.h>
using namespace std;
  
/* Link list node */
struct Node
{
    int data;
    Node* next, *arbit;
};
  
// This function populates arbit pointer in every
// node to the greatest value to its right.
void populateArbit(Node *head)
{
    // using static maxNode to keep track of maximum
    // orbit node address on right side
    static Node *maxNode;
  
    // 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
void printNextArbitPointers(Node *node)
{
    printf("Node\tNext Pointer\tArbit Pointer\n");
    while (node!=NULL)
    {
        cout << node->data << "\t\t";
  
        if(node->next)
            cout << node->next->data << "\t\t";
        else cout << "NULL" << "\t\t";
  
        if(node->arbit)
            cout << node->arbit->data;
        else cout << "NULL";
  
        cout << endl;
        node = node->next;
    }
}
  
/* Function to create a new node with given data */
Node *newNode(int data)
{
    Node *new_node = new Node;
    new_node->data = data;
    new_node->next = NULL;
    return new_node;
}
  
/* Driver program to test above functions*/
int main()
{
    Node *head = newNode(5);
    head->next = newNode(10);
    head->next->next = newNode(2);
    head->next->next->next = newNode(3);
  
    populateArbit(head);
  
    printf("Resultant Linked List is: \n");
    printNextArbitPointers(head);
  
    return 0;
}

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Java

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// 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\tNext Pointer\tArbit Pointer");
        while (node != null)
        {
            System.out.print(node.data + "\t\t\t");
  
            if (node.next != null)
                System.out.print(node.next.data + "\t\t\t\t");
            else
                System.out.print("NULL" +"\t\t\t");
  
            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    

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C#

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// C# program to point arbit pointers to highest
// value on its right
using System;
      
class GfG
{
  
    /* Link list node */
    public class Node
    {
        public int data;
        public 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)
    {
        Console.WriteLine("Node\tNext Pointer\tArbit Pointer");
        while (node != null)
        {
            Console.Write(node.data + "\t\t\t");
  
            if (node.next != null)
                Console.Write(node.next.data + "\t\t\t\t");
            else
                Console.Write("NULL" +"\t\t\t");
  
            if (node.arbit != null)
                Console.Write(node.arbit.data);
            else
                Console.Write("NULL");
  
            Console.WriteLine();
            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);
  
        Console.WriteLine("Resultant Linked List is: ");
        printNextArbitPointers(head);
  
    }
}
  
/* This code contributed by PrinciRaj1992 */

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Output:

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

This article is contributed by Aditya Goel. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above



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