Python Program To Add Two Numbers Represented By Linked Lists- Set 1

# 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 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 
            # there 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 "
Second List is ",
second.printList()

# Add the two lists and see result
res = LinkedList()
res.addTwoLists(first.head, second.head)
print "
Resultant list is ",
res.printList()
# This code is contributed by Nikhil Kumar Singh(nickzuck_007)