Python Program to Find the Largest Element in a Doubly Linked List

When it is required to find the largest element in a doubly linked list, a method to add elements to the doubly linked list, a method to print the elements of the doubly linked list, and a method to find the largest element in a doubly linked list are defined.

Below is a demonstration for the same −

Example

 Live Demo

class Node:    def __init__(self, data):       self.data = data       self.next = None       self.prev = None class DoublyLinkedList_structure:    def __init__(self):       self.first = None       self.last = None    def add_vals(self, data):       self.insert_at_end(Node(data))    def insert_at_end(self, newNode):       if self.last is None:          self.last = newNode          self.first = newNode       else:          newNode.prev = self.last          self.last.next = newNode          self.last = newNode def find_largest_val(my_list):    if my_list.first is None:       return None    largest_val = my_list.first.data    curr = my_list.first.next    while curr:       if curr.data > largest_val:          largest_val = curr.data       curr = curr.next    return largest_val my_instance = DoublyLinkedList_structure() my_list = input('Enter the elements in the doubly linked list ').split() for elem in my_list:    my_instance.add_vals(int(elem)) largest_val = find_largest_val(my_instance) if largest_val:    print('The largest element is {}.'.format(largest_val)) else:    print('The list is empty.')

Output

Enter the elements in the doubly linked list 45 12 67 89 234 567 888 44 999 The largest element is 999.

Explanation

• The ‘Node’ class is created.

• Another ‘DoublyLinkedList_structure’ 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’.

• A method named ‘add_vals’ is defined, that helps add a value to the stack.

• Another method named ‘insert_at_end’ is defined, that helps add a value to the end of the doubly linked list.

• Another method named ‘find_largest_val’ is defined, that helps find the largest value in the entire doubly linked list.

• An instance of the ‘DoublyLinkedList_structure’ is created.

• Elements are added to the linked list.

• The ‘find_largest_val’ method is called on this doubly linked list.

• The output is displayed on the console.