leetcode no.2 add two numbers

class (object):
    def __init__(self, x):
        self.val = x
        self.next = None
    def create(self, lst):
        cur = self
        for i,v in enumerate(lst):
            cur.val = v
            if i != len(lst) - 1:
                tmp = ListNode(0)
                cur.next = tmp
                cur = tmp

    def printf(self):
        head = self
        while head:
            print(head.val)
            head = head.next



class Solution(object):
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        list1 = []
        list2 = []
        while l1:
            list1.insert(0,str(l1.val))
            l1 = l1.next
        while l2:
            list2.insert(0,str(l2.val))
            l2 = l2.next
        sum1 = int(''.join(list1))
        sum2 = int(''.join(list2))
        sum = sum1 + sum2
        list3 = list(reversed(list(str(sum))))
        list3 = [int(x) for x in list3]
        return list3

if __name__ == "__main__":
    l1 = ListNode(0)
    l1.create([1,4,5])
    l1.printf()
    l2 = ListNode(0)
    l2.create([3,6,3])
    l2.printf()
    sol= Solution()
    ans = sol.addTwoNumbers(l1,l2)
    print(ans)

def addTwoNumbers(self, l1, l2):
        carry = 0
        cur = l3 = ListNode(0)
        while l1 or l2:
            sum = carry
            if l1:
                sum = sum + l1.val
                l1 = l1.next
            if l2:
                sum = sum + l2.val
                l2 = l2.next
            if sum >= 10:
                sum = sum - 10
                carry = 1
            else:
                carry = 0

            cur.val = sum
            if l1 or l2:
                tmp = ListNode(0)
                cur.next = tmp
                cur = tmp
        if carry == 1:
            tmp = ListNode(1)
            cur.next = tmp
        return l3