Add Two Numbers LeetCode solution in Python

1
class Solution:
2
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
3
        dummyHead = ListNode(0)
4
        tail = dummyHead
5
        carry = 0
6

7
        while l1 is not None or l2 is not None or carry != 0:
8
            digit1 = l1.val if l1 is not None else 0
9
            digit2 = l2.val if l2 is not None else 0
10

11
            sum = digit1 + digit2 + carry
12
            digit = sum % 10
13
            carry = sum // 10
14

15
            newNode = ListNode(digit)
16
            tail.next = newNode
17
            tail = tail.next
18

19
            l1 = l1.next if l1 is not None else None
20
            l2 = l2.next if l2 is not None else None
21

22
        result = dummyHead.next
23
        dummyHead.next = None
24
        return result