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Java Program To Check Whether The Length Of Given Linked List Is Even Or Odd

  • Last Updated : 10 Jan, 2022

Given a linked list, the task is to make a function which checks whether the length of the linked list is even or odd.
Examples: 

Input : 1->2->3->4->NULL
Output : Even

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

Method 1: Count the codes linearly 
Traverse the entire Linked List and keep counting the number of nodes. As soon as the loop is finished, we can check if the count is even or odd. You may try it yourself.
Method 2: Stepping 2 nodes at a time 
Approach:

1. Take a pointer and move that pointer two nodes at a time
2. At the end, if the pointer is NULL then length is Even, else Odd.

Java




// Java program to check length 
// of a given linklist 
import java.io.*;
  
class GfG{ 
  
// Defining structure 
static class Node 
    int data; 
    Node next; 
}
  
// Function to check the length 
// of linklist 
static int LinkedListLength(Node head) 
    while (head != null && 
           head.next != null
    
        head = head.next.next; 
    
    if (head == null
        return 0
    return 1
      
// Push function 
static void push(Node head, i
                 nt info) 
    // Allocating node 
    Node node = new Node(); 
      
    // Info into node 
    node.data = info; 
      
    // Next of new node to head 
    node.next = (head); 
  
    // head points to new node 
    (head) = node; 
  
// Driver code 
public static void main(String[] args) 
    Node head = null
      
    // Adding elements to Linked List 
    push(head, 4); 
    push(head, 5); 
    push(head, 7); 
    push(head, 2); 
    push(head, 9); 
    push(head, 6); 
    push(head, 1); 
    push(head, 2); 
    push(head, 0); 
    push(head, 5); 
    push(head, 5); 
    int check = 
        LinkedListLength(head); 
      
    // Checking for length of 
    // linklist 
    if(check == 0
    
        System.out.println("Odd"); 
    
    else
    
        System.out.println("Even"); 
    
}
// This code is contributed by Prerna saini

Output:  

Odd

Time Complexity: O(n) 
Space Complexity: O(1)

Please refer complete article on Check whether the length of given linked list is Even or Odd for more details!


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