题目：

题解：

# 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]:carry = 0p = l1q = l2dummy = ListNode(0)k = dummywhile p or q:val1 = p.val if p else 0val2 = q.val if q else 0n = val1 + val2 + carrycarry = n // 10res = n % 10node = ListNode(res)k.next = nodek = k.nextif p:p = p.nextif q:q = q.nextif carry:node = ListNode(carry)k.next = nodereturn dummy.next