[Leetcode][python]Add Two Numbers/两数相加

class Solution(object):
    def addTwoNumbers(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        dummy= ListNode(0)
        l = dummy
        jinwei = 0
        while l1 or l2 or jinwei:
            sum, jinwei = jinwei, 0
            if l1:
                sum += l1.val
                l1 = l1.next
            if l2:
                sum += l2.val
                l2 = l2.next
            if sum > 9: # 需要进位
                jinwei = 1
                sum -= 10
            l.next = ListNode(sum)
            l = l.next
        return dummy.next