leetcode-2-Add Two Numbers

2-Add Two Numbers

题目：

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

没什么特别需要注意的，链表这样的题，通常可以尝试加一个哑节点，这样可以使得代码处理更加简略一些。

后继题目leetcode-445. Add Two Numbers II

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode dump1 = new ListNode(0);
        ListNode dump2 = new ListNode(0);
        dump1.next = l1;
        dump2.next = l2;
        ListNode ret = dump1;
        int c = 0;
        while(dump1.next != null && dump2.next != null){
            dump1.next.val += dump2.next.val + c;
            c = dump1.next.val / 10;
            dump1.next.val %= 10;
            dump1 = dump1.next;
            dump2 = dump2.next;
        }
        if(dump2.next != null) dump1.next = dump2.next;
        while(dump1.next != null){
            dump1.next.val += c;
            c = dump1.next.val / 10;
            dump1.next.val %= 10;
            dump1 = dump1.next;
        }
        if(c==1)
            dump1.next = new ListNode(c);
        return ret.next;
    }
}