LeetCode题解 —— 2. Add Two Numbers

题目内容：

Difficulty: Medium　Total Accepted: 442.7K　Total Submissions: 1.6M

You are given two non-empty linked lists representing two non-negative integers. 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.
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.

题目描述

读完题目和给出的例子，我们发现本题是将数字用链表进行倒序存储，342用链表存储表示为2 -> 4 -> 3，同样两个数加和的结果也是这样存储，这就有一个需要注意的地方，两个加数每位上的数字加和逢十进一的时候，结果链表中倒序存储，所以进位是向后的。

解题思路及代码实现(java)

public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        int carry =0;

        ListNode newHead = new ListNode(0);
        ListNode p1 = l1, p2 = l2, p3=newHead;

        while(p1 != null || p2 != null){
            if(p1 != null){
                carry += p1.val;
                p1 = p1.next;
            }

            if(p2 != null){
                carry += p2.val;
                p2 = p2.next;
            }

            p3.next = new ListNode(carry%10);
            p3 = p3.next;
            carry /= 10;
        }

        if(carry==1) 
            p3.next=new ListNode(1);

        return newHead.next;
    }
}