Find middle of singly linked list Recursively

Given a singly linked list and the task is to find the middle of the linked list.
Examples:

Input  : 1->2->3->4->5  
Output : 3

Input  : 1->2->3->4->5->6
Output : 4

We have already discussed Iterative Solution. In this post iterative solution is discussed. Count total number of nodes in the list in recursive manner and do half of this, suppose this value is n. Then rolling back through recursion decrement n by one for each call. Return the node where n is zero.



C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ program for Recursive approach to find
// middle of singly linked list
#include <iostream>
using namespace std;
  
// Tree Node Structure
struct Node
{
    int data;
    struct Node* next;
};
  
// Create new Node
Node* newLNode(int data)
{
    Node* temp = new Node;
    temp->data = data;
    temp->next = NULL;
    return temp;
}
  
// Function for finding midpoint recursively
void midpoint_util(Node* head, int* n, Node** mid)
{
  
    // If we reached end of linked list
    if (head == NULL)
    {
        *n = (*n) / 2;
        return;
    }
  
    *n = *n + 1;
  
    midpoint_util(head->next, n, mid);
  
    // Rolling back, decrement n by one
    *n = *n - 1;
    if (*n == 0)
    {
  
        // Final answer
        *mid = head;
    }
}
  
Node* midpoint(Node* head)
{
    Node* mid = NULL;
    int n = 1;
    midpoint_util(head, &n, &mid);
    return mid;
}
  
int main()
{
    Node* head = newLNode(1);
    head->next = newLNode(2);
    head->next->next = newLNode(3);
    head->next->next->next = newLNode(4);
    head->next->next->next->next = newLNode(5);
    Node* result = midpoint(head);
    cout << result->data << endl;
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java program for Recursive approach to find 
// middle of singly linked list 
class GFG
{
  
// Tree Node Structure 
static class Node 
    int data; 
    Node next; 
}; 
  
// Create new Node 
static Node newLNode(int data) 
    Node temp = new Node(); 
    temp.data = data; 
    temp.next = null
    return temp; 
  
static int n;
static Node mid;
  
// Function for finding midpoint recursively 
static void midpoint_util(Node head ) 
  
    // If we reached end of linked list 
    if (head == null
    
        n = (n) / 2
        return
    
  
    n = n + 1
  
    midpoint_util(head.next); 
  
    // Rolling back, decrement n by one 
    n = n - 1
    if (n == 0
    
  
        // Final answer 
        mid = head; 
    
  
static Node midpoint(Node head) 
    mid = null
    n = 1
    midpoint_util(head); 
    return mid; 
  
// Driver code
public static void main(String args[])
    Node head = newLNode(1); 
    head.next = newLNode(2); 
    head.next.next = newLNode(3); 
    head.next.next.next = newLNode(4); 
    head.next.next.next.next = newLNode(5); 
    Node result = midpoint(head); 
    System.out.print( result.data ); 
}
  
// This code is contributed by Arnab Kundu 

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# program for Recursive approach to find 
// middle of singly linked list 
using System; 
class GFG
{
  
// Tree Node Structure 
public class Node 
    public int data; 
    public Node next; 
}; 
  
// Create new Node 
static Node newLNode(int data) 
    Node temp = new Node(); 
    temp.data = data; 
    temp.next = null
    return temp; 
  
static int n;
static Node mid;
  
// Function for finding midpoint recursively 
static void midpoint_util(Node head ) 
  
    // If we reached end of linked list 
    if (head == null
    
        n = (n) / 2; 
        return
    
  
    n = n + 1; 
  
    midpoint_util(head.next); 
  
    // Rolling back, decrement n by one 
    n = n - 1; 
    if (n == 0) 
    
  
        // Final answer 
        mid = head; 
    
  
static Node midpoint(Node head) 
    mid = null
    n = 1; 
    midpoint_util(head); 
    return mid; 
  
// Driver code
public static void Main()
    Node head = newLNode(1); 
    head.next = newLNode(2); 
    head.next.next = newLNode(3); 
    head.next.next.next = newLNode(4); 
    head.next.next.next.next = newLNode(5); 
    Node result = midpoint(head); 
    Console.WriteLine( result.data ); 
}
}
  
// This code is contributed by Rajput-Ji

chevron_right



Output:

3


My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.



Improved By : andrew1234, Rajput-Ji



Article Tags :
Practice Tags :


1


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.