addition of linkedlist.py

# Python program to add two numbers represented by linked list

# Node class


class Node:

	# Constructor to initialize the node object
	def __init__(self, data):
		self.data = data
		self.next = None


class LinkedList:

	# Function to initialize head
	def __init__(self):
		self.head = None

	# Function to reverse the linked list
	def reverse(self):
		prev = None
		current = self.head
		while(current is not None):
			next = current.next
			current.next = prev
			prev = current
			current = next
		self.head = prev

	# Function to insert a new node at the beginning
	def push(self, new_data):
		new_node = Node(new_data)
		new_node.next = self.head
		self.head = new_node

	# Add contents of two linked lists and return the head
	# node of resultant list
	def addTwoLists(self, first, second):
		prev = None
		temp = None
		carry = 0

		# While both list exists
		while(first is not None or second is not None):

			# Calculate the value of next digit in
			# resultant list
			# The next digit is sum of following things
			# (i) Carry
			# (ii) Next digit of first list (if ther is a
			# next digit)
			# (iii) Next digit of second list ( if there
			# is a next digit)
			fdata = 0 if first is None else first.data
			sdata = 0 if second is None else second.data
			Sum = carry + fdata + sdata

			# update carry for next calculation
			carry = 1 if Sum >= 10 else 0

			# update sum if it is greater than 10
			Sum = Sum if Sum < 10 else Sum % 10

			# Create a new node with sum as data
			temp = Node(Sum)

			# if this is the first node then set it as head
			# of resultant list
			if self.head is None:
				self.head = temp
			else:
				prev.next = temp

			# Set prev for next insertion
			prev = temp

			# Move first and second pointers to next nodes
			if first is not None:
				first = first.next
			if second is not None:
				second = second.next

		if carry > 0:
			temp.next = Node(carry)

	# Utility function to print the linked LinkedList
	def printList(self):
		temp = self.head
		while(temp):
			print(temp.data)
			temp = temp.next


# Driver code
first = LinkedList()
second = LinkedList()

# Create first list
first.push(6)
first.push(4)
first.push(9)
first.push(5)
first.push(7)
print("First List is ")
first.printList()
 



# Create second list
second.push(4)
second.push(8)
print("\nSecond List is ")
second.printList()
first.printList()
 

# Add the two lists and see result
res = LinkedList()
res.addTwoLists(first.head, second.head)
print("\nResultant list is ")
res.printList()