LeetCode 2. 两数相加

示例：

输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
输出：7 -> 0 -> 8
原因：342 + 465 = 807

# Definition for singly-linked list.
class ListNode():
    def __init__(self, val):
        if isinstance(val, int):
            self.val = val
            self.next = None

        elif isinstance(val, list):
            self.val = val[0]
            self.next = None
            cur = self
            for i in val[1:]:
                cur.next = ListNode(i)
                cur = cur.next

    def gatherAttrs(self):
        return ", ".join("{}: {}".format(k, getattr(self, k)) for k in self.__dict__.keys())

    def __str__(self):
        return self.__class__.__name__ + " {" + "{}".format(self.gatherAttrs()) + "}"


class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        if isinstance(l1, list):
            l1 = ListNode(l1)
            l2 = ListNode(l2)
        re = ListNode(0)
        r = re
        carry = 0
        while (l1 or l2):
            x = l1.val if l1 else 0
            y = l2.val if l2 else 0
            z = x + y + carry
            carry = z//10
            r.next = ListNode(z % 10)
            r = r.next
            if (l1 != None): l1 = l1.next
            if (l2 != None): l2 = l2.next
        #最后进位
        if carry > 0:
            r.next = ListNode(1)

        return re.next

if __name__ == '__main__':
    test = Solution()
    print(test.addTwoNumbers([1, 3], [2, 1, 3]))