You are given twonon-emptylinked lists representing two non-negative integers. The digits are stored inreverse orderand each of their nodes contain a single digit. Add the two numbers and return it as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Example
Input:(2 -> 4 -> 3) + (5 -> 6 -> 4)
Output:7 -> 0 -> 8
Explanation:342 + 465 = 807.
这道题的思路比较直接， 从第一个数开始一直到最后一个，两两相加。几点需要主要
1. 进位
2. 不对称 -- 两个数组不一样长。举个例子 （2） + (5 -> 6 -> 4)， 这个时候注意用Null 补齐
Java Code：
