question4.py

# 4  Add two numbers as a linked list

class ListNode(object):
    def __init__(self, x):
        self.val = x
        self.next = None
        
class Solution(object):
    def addTwoNumbers(self, l1, l2):
        result = ListNode(0)
        result_tail = result
        carry = 0
                
        while l1 or l2 or carry:            
            val1  = (l1.val if l1 else 0)
            val2  = (l2.val if l2 else 0)
            carry, out = divmod(val1+val2 + carry, 10)    
                      
            result_tail.next = ListNode(out)
            result_tail = result_tail.next                      
            
            l1 = (l1.next if l1 else None)
            l2 = (l2.next if l2 else None)
               
        return result.next
        
l1 = ListNode(2)
l1.next = ListNode(4)
l1.next.next = ListNode(3)
l2 = ListNode(5)
l2.next = ListNode(6)
l2.next.next = ListNode(4)
result = Solution().addTwoNumbers(l1, l2)
while result:
    print (result.val),
    result = result.next