Leetcode2:Add Two Numbers@Python

You are given two linked lists representing two non-negative numbers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

 #-*-coding:utf-8-*-

 #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
         """
         tens = 0                          # l1.val+l2.val所得和的十位数，初始化0
         units = 0                         # l1.val+l2.val所得和的个位数，初始化0
         l_origin = ListNode(0)            # 表示一个链表的头结点
         l = l_origin
         while(l1 or l2 or tens!=0):
             val = tens
             if l1:
                 val = val + l1.val
                 l1 = l1.next
             if l2:
                 val = val + l2.val
                 l2 = l2.next
             units = val % 10
             tens = val / 10
             node = ListNode(units)
             l.next = node
             l = l.next
         return l_origin.next              # 返回所求列表

在Leetcode上提交时直接提交Solution类，结点定义不用提交。

在做这题时用到带有头结点的链表，比不带头结点的链表使用时方便的多。