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Find the fractional (or n/k – th) node in linked list

Given a singly linked list and a number k, write a function to find the (n/k)-th element, where n is the number of elements in the list. We need to consider ceil value in case of decimals.

Examples:

Input : list = 1->2->3->4->5->6 
        k = 2
Output : 3
Since n = 6 and k = 2, we print (6/2)-th node 
which is 3.

Input : list = 2->7->9->3->5
        k = 3
Output : 7 
Since n is 5 and k is 3, we print ceil(5/3)-th 
node which is 2nd node, i.e., 7.



  1. Take two pointers temp and fractionalNode and initialize them with null and head respectively.
  2. For every k jumps of the temp pointer, make one jump of the fractionalNode pointer.

C++

// C++ program to find fractional node in a linked list
#include <bits/stdc++.h>
  
/* Linked list node */
struct Node {
    int data;
    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;
}
  
/* Function to find fractional node in the linked list */
Node* fractionalNodes(Node* head, int k)
{
    // Corner cases
    if (k <= 0 || head == NULL)
        return NULL;
  
    Node* fractionalNode = NULL;
      
    // Traverse the given list 
    int i = 0;
    for (Node* temp = head; temp != NULL; temp = temp->next) {
  
        // For every k nodes, we move fractionalNode one
        // step ahead. 
        if (i % k == 0) {
  
            // First time we see a multiple of k
            if (fractionalNode == NULL)
                fractionalNode = head;
  
            else
                fractionalNode = fractionalNode->next;
        }
        i++;
    }
    return fractionalNode;
}
  
// A utility function to print a linked list
void printList(Node* node)
{
    while (node != NULL) {
        printf("%d ", node->data);
        node = node->next;
    }
    printf(" ");
}
  
/* Driver program to test above function */
int main(void)
{
    Node* head = newNode(1);
    head->next = newNode(2);
    head->next->next = newNode(3);
    head->next->next->next = newNode(4);
    head->next->next->next->next = newNode(5);
    int k = 2;
  
    printf("List is ");
    printList(head);
  
    Node* answer = fractionalNodes(head, k);
    printf(" Fractional node is ");
    printf("%d ", answer->data);
  
    return 0;
}

Java

// Java program to find fractional node in
// a linked list
public class FractionalNodell
{
    /* Linked list node */
    static class Node{
        int data;
        Node next;
  
        //Constructor
        Node (int data){
            this.data = data;
        }
    }
  
    /* Function to find fractional node in the
       linked list */
    static Node fractionalNodes(Node head, int k)
    {
        // Corner cases
        if (k <= 0 || head == null)
            return null;
  
        Node fractionalNode = null;
  
        // Traverse the given list
        int i = 0;
        for (Node temp = head; temp != null;
                          temp = temp.next){
  
            // For every k nodes, we move
            // fractionalNode one step ahead.
            if (i % k == 0){
  
                // First time we see a multiple of k
                if (fractionalNode == null)
                    fractionalNode = head;
                else
                    fractionalNode = fractionalNode.next;
            }
            i++;
        }
        return fractionalNode;
    }
  
    // A utility function to print a linked list
    static void printList(Node node)
    {
        while (node != null)
        {
            System.out.print(node.data+" ");
            node = node.next;
        }
        System.out.println();
    }
  
    /* Driver program to test above function */
    public static void main(String[] args) {
        Node head = new Node(1);
        head.next = new Node(2);
        head.next.next = new Node(3);
        head.next.next.next = new Node(4);
        head.next.next.next.next = new Node(5);
        int k =2;
  
        System.out.print("List is ");
        printList(head);
  
        Node answer = fractionalNodes(head, k);
        System.out.println("Fractional node is "+
                                      answer.data);
    }
}
// This code is contributed by Sumit Ghosh

C#

// C# program to find fractional node in
// a linked list
using System;
  
public class FractionalNodell
{
    /* Linked list node */
    public class Node
    {
        public int data;
        public Node next;
  
        //Constructor
        public Node (int data)
        {
            this.data = data;
        }
    }
  
    /* Function to find fractional node in the
    linked list */
    static Node fractionalNodes(Node head, int k)
    {
        // Corner cases
        if (k <= 0 || head == null)
            return null;
  
        Node fractionalNode = null;
  
        // Traverse the given list
        int i = 0;
        for (Node temp = head; temp != null;
                        temp = temp.next)
        {
  
            // For every k nodes, we move
            // fractionalNode one step ahead.
            if (i % k == 0)
            {
  
                // First time we see a multiple of k
                if (fractionalNode == null)
                    fractionalNode = head;
                else
                    fractionalNode = fractionalNode.next;
            }
            i++;
        }
        return fractionalNode;
    }
  
    // A utility function to print a linked list
    static void printList(Node node)
    {
        while (node != null)
        {
            Console.Write(node.data+" ");
            node = node.next;
        }
        Console.WriteLine();
    }
  
    /* Driver code */
    public static void Main(String[] args) 
    {
        Node head = new Node(1);
        head.next = new Node(2);
        head.next.next = new Node(3);
        head.next.next.next = new Node(4);
        head.next.next.next.next = new Node(5);
        int k =2;
  
        Console.Write("List is ");
        printList(head);
  
        Node answer = fractionalNodes(head, k);
        Console.WriteLine("Fractional node is "+
                                    answer.data);
    }
}
  
// This code is contributed by Rajput-Ji


Output:

List is 1 2 3 4 5 
Fractional node is 3

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This article is attributed to GeeksforGeeks.org

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