#### 题目比较简单，注意进位，直接上代码
```
class Solution:
def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
first, second = l1, l2
dummy = ListNode(0, None)
curr = dummy
flag = 0
while first or second:
result = flag
flag = 0
if first:
result += first.val
if second:
result += second.val
if result >= 10:
flag = 1
result -= 10
newNode = ListNode(result, None)
curr.next = newNode
curr = curr.next
if first:
first = first.next
if second:
second = second.next
if flag == 1:
lastNode = ListNode(flag, None)
curr.next = lastNode
return dummy.next
```