[LeetCode] 2. Add Two Numbers

Python

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def addTwoNumbers(self, l1: Optional[ListNode], l2: Optional[ListNode]) -> Optional[ListNode]:
        answer = ListNode()
        temp = answer
        carry = 0
        print(l1)
        print(l1.next)
        while l1 or l2 or carry:
            sum = 0
            if l1:
                sum += l1.val
                l1 = l1.next
            if l2:
                sum += l2.val
                l2 = l2.next
            sum += carry
            carry = sum // 10
            sum = sum % 10
            temp.next = ListNode(sum)
            temp = temp.next
            
        return answer.next