leetcode刷题详解——Add Two Numbers（02）

题目地址：https://leetcode.com/problems/add-two-numbers/#/description

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.

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

题目解析：

这道题主要是考察列表和数字相加，意思简单，但是需要注意一下两点：

1.如何处理不同长度的数字，即两个列表长度不一样

2.以及进位和最高位的判断

方法解析：

1.递归的方法

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {return process(l1,l2,0);    }public static ListNode process(ListNode l1,ListNode l2,int jinwei){if(l1==null && l2 == null){return jinwei==0?null : new ListNode(jinwei);}if(l1==null && l2!=null){//如果l1为空补0l1 = new ListNode(0);}if(l2==null && l1!=null){//入伙l2为空补0l2 = new ListNode(0);}int sum  = l1.val + l2.val + jinwei;ListNode node = new ListNode(sum%10);node.next = process(l1.next,l2.next,sum/10);return node;}