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Python Program to Find the Length of the Linked List using Recursion
When it is required to find the length of a linked list with the help of recursion, a method to add elements to the linked list, and a method to calculate the length of the linked list is defined. A helper function is defined that is called with the help of the previously defined length calculation method.
Below is a demonstration for the same −
Example
class Node:
def __init__(self, data):
self.data = data
self.next = None
class my_linked_list:
def __init__(self):
self.head = None
self.last_node = None
def add_value(self, my_data):
if self.last_node is None:
self.head = Node(my_data)
self.last_node = self.head
else:
self.last_node.next = Node(my_data)
self.last_node = self.last_node.next
def calculate_length(self):
return self.length_helper_fun(self.head)
def length_helper_fun(self, curr):
if curr is None:
return 0
return 1 + self.length_helper_fun(curr.next)
my_instance = my_linked_list()
my_data = input('Enter elements of the linked list ').split()
for elem in my_data:
my_instance.add_value(int(elem))
print('The length of the linked list is ' + str(my_instance.calculate_length()))Output
Enter elements of the linked list 12 45 32 67 88 0 99 The length of the linked list is 7
Explanation
The ‘Node’ class is created.
Another ‘my_linked_list’ class with required attributes is created.
It has an ‘init’ function that is used to initialize the first element, i.e the ‘head’ to ‘None’ and last node to ‘None’.
Another method named ‘add_value’ is defined, that is used to add data to the linked list.
Another method named ‘calculate_length’ is defined that is used to call the helper function to find the length of the linked list.
The helper function is defined, since recursion needs to be used here.
It checks for the current value of node, and returns the length of the list.
An object of the ‘my_linked_list’ class is created.
The user input is taken for the elements in the linked list.
Methods are called on it to add data.
The calculate_length method is called, and output is displayed on the console.
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