[leetcode]两数相加

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(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
def addTwoNumbers(self, l1, l2):
"""
:type l1: ListNode
:type l2: ListNode
:rtype: ListNode
"""
p = res = ListNode(-1)
carry = 0
while l1 and l2:
num = l1.val + l2.val + carry
carry, val = divmod(num, 10)
p.next = ListNode(val)
l1 = l1.next
l2 = l2.next
p = p.next
l3 = l1 or l2
while l3:
num = l3.val + carry
carry, val = divmod(num, 10)
p.next = ListNode(val)
p = p.next
l3 = l3.next
if carry != 0:
p.next = ListNode(carry)
p = p.next
return res.next