给出两个 非空 的链表用来表示两个非负的整数。其中，它们各自的位数是按照 逆序 的方式存储的，并且它们的每个节点只能存储 一位 数字。如果，我们将这两个数相加起来，则会返回一个新的链表来表示它们的和。您可以假设除了数字 0 之外，这两个数都不会以 0 开头。
示例：
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| 输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)
输出：7 -> 0 -> 8
原因：342 + 465 = 807
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解法
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| # Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def addTwoNumbers(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
sum_node = ListNode(-1)
head = sum_node
carry = 0
while l1 and l2:
sum_val = l1.val + l2.val + carry
val = sum_val % 10
carry = sum_val // 10
sum_node.next = ListNode(val)
sum_node = sum_node.next
l1 = l1.next
l2 = l2.next
while l1:
sum_val = l1.val + carry
val = sum_val % 10
carry = sum_val // 10
sum_node.next = ListNode(val)
l1 = l1.next
sum_node = sum_node.next
while l2:
sum_val = l2.val + carry
val = sum_val % 10
carry = sum_val // 10
sum_node.next = ListNode(val)
l2 = l2.next
sum_node = sum_node.next
if l1 is None and l2 is None and carry > 0:
sum_node.next = ListNode(carry)
return head.next
|