linkedlist

# Node class
class Node:

    # Function to initialize the node object
    def __init__(self, data):
        self.data = data # Assign data
        self.next = None # Initialize next as null

# Linked List class
class LinkedList:

    # Function to initialize the Linked List object
    def __init__(self):
        self.head = None
    def print_linkedlist(self):
        nodes = []
        node = self.head
        while node:
            nodes.append(node.data)
            node = node.next
        nodes.append('None')
        print('->'.join(nodes))

one = Node("1")
two = Node('2')
three = Node('3')
llist = LinkedList()
llist.head = one
one.next = two
two.next = three

def push(self, new_data):

    # 1 & 2: Allocate the Node &
    #    Put in the data
    new_node = Node(new_data)

    # 3. Make next of new Node as head
    new_node.next = self.head

    # 4. Move the head to point to new Node
    self.head = new_node

def insertLast(self, new_data):
    #create a new node
    new_node = Node(new_data)

    #if linkedlist is empty, make the new node as head
    if self.head is None:
        self.head = new_node
        return
    #else traverse till the last node
    last = self.head
    while (last.next):
        last = last.next

    #change the next of last node
    last.next = new_node


def del_node(self, data_to_del):
    #store head node
    node = self.head

    #if head node itself hold the key to be deleted
    if node is not None:
        if node.data== data_to_del:
            self.head = node.next
            node = None
            return

    # search for the data to be deleted, keep track of
    # the prev_node as we need to change 'prev.next'

    while node is not None:
        if node.data ==data_to_del:
            break
        prev_node = node
        node = node.next

    #if key was not present in Linked list
    if node == None:
        return

    #unlink the node from linked list
    prev_node.next = node.next
    node = None