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

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!