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

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  • 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.

Python3




# Python program to check length 
# of a given linklist 
# Defining structure 
class Node: 
    def __init__(self, d):
        self.data = d
        self.next = None
        self.head = None
  
    # Function to check the length 
    # of linklist 
    def LinkedListLength(self):
        while (self.head != None and 
               self.head.next != None): 
            self.head = self.head.next.next
              
        if(self.head == None):
            return 0
        return 1
      
    # Push function 
    def push(self, info):
          
    # Allocating node 
        node = Node(info) 
  
    # Next of new node to head 
        node.next = (self.head) 
  
    # head points to new node 
        (self.head) = node 
  
# Driver code 
head = Node(0
      
# Adding elements to Linked List 
head.push(4
head.push(5
head.push(7
head.push(2
head.push(9
head.push(6
head.push(1
head.push(2
head.push(0
head.push(5
head.push(5
check = head.LinkedListLength()
      
# Checking for length of 
# linklist 
if(check == 0):
    print("Even")
else:
    print("Odd")
# 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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