问题描述：

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

基本思路：

此题很简单，一位一位加即可。

代码：

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {  //JAVA

	public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

		ListNode rl1 = l1;
		ListNode rl2 = l2;
		ListNode result = new ListNode(0);
		
		ListNode restmp = result;
		int res = 0;
		while(rl1 !=null || rl2 != null){
			int num;
			if(rl1 == null)
				num = rl2.val + res;
			else if(rl2 == null)
				num = rl1.val + res;
			else num = rl1.val + rl2.val +res;
			
			if(num/10 >0)
			{
				res = 1;
				num = num%10;
			}
			else
			{
			    res = 0;
			}
			ListNode tmp = new ListNode(num);
			restmp.next = tmp;
			restmp = tmp;
			
			if(rl1 != null)
			    rl1 = rl1.next;
			if(rl2 != null)
			    rl2 = rl2.next;
			
		}
		if(res == 1){
			ListNode tmp = new ListNode(1);
			restmp.next = tmp;
			restmp = tmp;
		}
		return result.next;
			
        
    }
}

[leetcode]Add Two Numbers