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。