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Replace each node with its Surpasser Count in Linked List

  • Last Updated : 07 Jun, 2021
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Given LinkedList, replace each node’s value with its surpasser count. That is the count of elements which are greater towards its right.
Examples: 
 

Input : 10->12->5->40->21->70->1->49->37->NULL 
Output : 6->5->5->2->3->0->2->0->0->NULL 
Explanation : 
Element in the first node is 10 and the number of elements to the right of the node that are greater than 10 is 6. Therefore replace the node with 6
Element in the first node is 12 and the number of elements to the right of the node that are greater than 12 is 5. Therefore replace the node with 5
Similarly, replace for all the elements in the list.
Input : 5->4->6->3->2->NULL 
Output : 1->1->0->0->0->NULL 
 

 

Simple Approach
 

  1. Take two pointers p and x. The pointer p is used to traverse the list and x is used to traverse the right half of the list for every node.
  2. Initialize a variable count to count the nodes greater than the current nodes.
  3. Traverse through all the nodes in the list using the pointer p. 
    • Initialize the count to 0.
    • Initialize the pointer x to point the current node p.
    • Count the number of nodes that are greater than the current node.
    • Replace the current node with the count.
  4. Repeat step 4 until the list is traversed completely.

Below is the implementation of the above approach:
 



C++




// C++ program to replace the nodes
// with their surpasser count
 
#include <bits/stdc++.h>
using namespace std;
 
// A linked list node
struct Node {
    int data;
    struct Node* next;
};
 
// Utility function to create a new Node
Node* newNode(int data)
{
    Node* temp = new Node;
    temp->data = data;
    temp->next = NULL;
 
    return temp;
}
 
// Function to display the linked list
void printList(Node* node)
{
    while (node != NULL) {
 
        cout << node->data << " ";
 
        node = node->next;
    }
}
 
// Function to check Surpasser Count
void replaceNodes(Node* head)
{
    // Pointer used to traverse through
    // all the nodes in the list
    Node* p = head;
 
    // Pointer used to traverse through the right
    // elements to count the greater elements
    Node* x = NULL;
 
    // Variable to count the number of
    // elements greater than the
    // current element on right
    int count = 0;
 
    int i;
 
    // Traverse through all the elements
    // in the list
    while (p != NULL) {
 
        count = 0;
 
        i = 0;
 
        // Initialize x to current node
        x = p;
 
        // Check or count the number of nodes
        // that are greater than the current
        // node on right
        while (x != NULL) {
 
            if (x->data > p->data)
                count++;
 
            x = x->next;
        }
 
        // Replace the node data with the
        // count of elements greater than
        // the current element
        p->data = count;
        p = p->next;
    }
}
 
// Driver code
int main()
{
    // Creating the linked list
    Node* head = newNode(10);
    head->next = newNode(12);
    head->next->next = newNode(5);
    head->next->next->next = newNode(40);
    head->next->next->next->next = newNode(21);
    head->next->next->next->next->next = newNode(70);
    head->next->next->next->next->next->next = newNode(1);
    head->next->next->next->next->next->next->next = newNode(49);
    head->next->next->next->next->next->next->next->next = newNode(37);
 
    replaceNodes(head);
 
    printList(head);
 
    return 0;
}

Java




// Java program to replace the nodes
// with their surpasser count
 
class GFG {
 
// A linked list node
static class Node {
    int data;
    Node next;
};
  
// Utility function to create a new Node
static Node newNode(int data)
{
    Node temp = new Node();
    temp.data = data;
    temp.next = null;
  
    return temp;
}
  
// Function to display the linked list
static void printList(Node node)
{
    while (node != null) {
        System.out.print(node.data+" ");
  
        node = node.next;
    }
}
  
// Function to check Surpasser Count
static void replaceNodes(Node head)
{
    // Pointer used to traverse through
    // all the nodes in the list
    Node p = head;
  
    // Pointer used to traverse through the right
    // elements to count the greater elements
    Node x = null;
  
    // Variable to count the number of
    // elements greater than the
    // current element on right
    int count = 0;
  
    int i;
  
    // Traverse through all the elements
    // in the list
    while (p != null) {
  
        count = 0;
  
        i = 0;
  
        // Initialize x to current node
        x = p;
  
        // Check or count the number of nodes
        // that are greater than the current
        // node on right
        while (x != null) {
  
            if (x.data > p.data)
                count++;
  
            x = x.next;
        }
  
        // Replace the node data with the
        // count of elements greater than
        // the current element
        p.data = count;
        p = p.next;
    }
}
  
// Driver code
public static void main(String[] args) {
  // Creating the linked list
    Node head = newNode(10);
    head.next = newNode(12);
    head.next.next = newNode(5);
    head.next.next.next = newNode(40);
    head.next.next.next.next = newNode(21);
    head.next.next.next.next.next = newNode(70);
    head.next.next.next.next.next.next = newNode(1);
    head.next.next.next.next.next.next.next = newNode(49);
    head.next.next.next.next.next.next.next.next = newNode(37);
  
    replaceNodes(head);
  
    printList(head);
    }
}
 
// This code has been contributed by 29AjayKumar

Python3




# Python3 program to replace the nodes
# with their surpasser count
 
# A linked list node
class Node:
     
    def __init__(self, data):
        self.data = data
        self.next = None
 
# Function to display the linked list
def printList(node):
 
    while node != None:
        print(node.data, end = " ")
        node = node.next
     
# Function to check Surpasser Count
def replaceNodes(head):
 
    # Pointer used to traverse through
    # all the nodes in the list
    p = head
 
    # Pointer used to traverse through
    # the right elements to count the
    # greater elements
    x = None
 
    # Variable to count the number of
    # elements greater than the
    # current element on right
    count = 0
 
    # Traverse through all the elements
    # in the list
    while p != None:
 
        count = 0
 
        # Initialize x to current node
        x = p
 
        # Check or count the number of nodes
        # that are greater than the current
        # node on right
        while x != None:
 
            if x.data > p.data:
                count += 1
 
            x = x.next
 
        # Replace the node data with the
        # count of elements greater than
        # the current element
        p.data = count
        p = p.next
 
# Driver code
if __name__ == "__main__":
 
    # Creating the linked list
    head = Node(10)
    head.next = Node(12)
    head.next.next = Node(5)
    head.next.next.next = Node(40)
    head.next.next.next.next = Node(21)
    head.next.next.next.next.next = Node(70)
    head.next.next.next.next.next.next = Node(1)
    head.next.next.next.next.next.next.next = Node(49)
    head.next.next.next.next.next.next.next.next = Node(37)
 
    replaceNodes(head)
 
    printList(head)
 
# This code is contributed by Rituraj Jain

C#




// C# program to replace the nodes
// with their surpasser count
using System;
 
class GFG
{
 
// A linked list node
public class Node
{
    public int data;
    public Node next;
};
 
// Utility function to create a new Node
static Node newNode(int data)
{
    Node temp = new Node();
    temp.data = data;
    temp.next = null;
 
    return temp;
}
 
// Function to display the linked list
static void printList(Node node)
{
    while (node != null)
    {
        Console.Write(node.data + " ");
 
        node = node.next;
    }
}
 
// Function to check Surpasser Count
static void replaceNodes(Node head)
{
    // Pointer used to traverse through
    // all the nodes in the list
    Node p = head;
 
    // Pointer used to traverse through the right
    // elements to count the greater elements
    Node x = null;
 
    // Variable to count the number of
    // elements greater than the
    // current element on right
    int count = 0;
 
    int i;
 
    // Traverse through all the elements
    // in the list
    while (p != null)
    {
 
        count = 0;
 
        i = 0;
 
        // Initialize x to current node
        x = p;
 
        // Check or count the number of nodes
        // that are greater than the current
        // node on right
        while (x != null)
        {
 
            if (x.data > p.data)
                count++;
 
            x = x.next;
        }
 
        // Replace the node data with the
        // count of elements greater than
        // the current element
        p.data = count;
        p = p.next;
    }
}
 
// Driver code
public static void Main()
{
    // Creating the linked list
    Node head = newNode(10);
    head.next = newNode(12);
    head.next.next = newNode(5);
    head.next.next.next = newNode(40);
    head.next.next.next.next = newNode(21);
    head.next.next.next.next.next = newNode(70);
    head.next.next.next.next.next.next = newNode(1);
    head.next.next.next.next.next.next.next = newNode(49);
    head.next.next.next.next.next.next.next.next = newNode(37);
 
    replaceNodes(head);
 
    printList(head);
}
}
 
/* This code contributed by PrinciRaj1992 */

Javascript




<script>
 
// JavaScript program to replace the nodes
// with their surpasser count
 
// A linked list node
class Node {
        constructor() {
                this.data = 0;
                this.next = null;
             }
        }
         
// Utility function to create a new Node
function newNode( data)
{
    var temp = new Node();
    temp.data = data;
    temp.next = null;
 
    return temp;
}
 
// Function to display the linked list
function printList( node)
{
    while (node != null) {
        document.write(node.data+" ");
 
        node = node.next;
    }
}
 
// Function to check Surpasser Count
function replaceNodes( head)
{
    // Pointer used to traverse through
    // all the nodes in the list
    var p = head;
 
    // Pointer used to traverse through the right
    // elements to count the greater elements
    var x = null;
 
    // Variable to count the number of
    // elements greater than the
    // current element on right
    let count = 0;
 
    let i;
 
    // Traverse through all the elements
    // in the list
    while (p != null) {
 
        count = 0;
 
        i = 0;
 
        // Initialize x to current node
        x = p;
 
        // Check or count the number of nodes
        // that are greater than the current
        // node on right
        while (x != null) {
 
            if (x.data > p.data)
                count++;
 
            x = x.next;
        }
 
        // Replace the node data with the
        // count of elements greater than
        // the current element
        p.data = count;
        p = p.next;
    }
}
 
 
// Driver Code
 
// Creating the linked list
var head = newNode(10);
head.next = newNode(12);
head.next.next = newNode(5);
head.next.next.next = newNode(40);
head.next.next.next.next = newNode(21);
head.next.next.next.next.next = newNode(70);
head.next.next.next.next.next.next = newNode(1);
head.next.next.next.next.next.next.next = newNode(49);
head.next.next.next.next.next.next.next.next = newNode(37);
 
replaceNodes(head);
 
printList(head);
 
</script>
Output: 
6 5 5 2 3 0 2 0 0

 

Time Complexity: O(N2) where N is the number of nodes in the linked list. 
Auxiliary Space: O(1)
 

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