LeetCode-Java-2. Add Two Numbers

题目

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.
你有两个非空链表，表示两个非负整数，数字以相反的顺序存储，每个节点中包含一个单独的数字。两个数字相加，并且返回结果一个链表。
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
你可以假设两个数字的最开始不包括0，除了0自己。
Example
例子
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.

代码

正常思想一个节点一个节点走，注意需要设置一个进位项。

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode n = new ListNode(0);
        ListNode p = l1,q=l2,c=n;
        int carry=0;
        while(p!=null||q!=null)
        {   
            int x = (p!=null)?p.val:0;
            int y = (q!=null)?q.val:0;
            int sum = x+y+carry;
            carry = sum/10;
            c.next = new ListNode(sum%10);
            c = c.next;
            if(q!=null) q=q.next;
            if(p!=null) p=p.next;
        }
        if(carry>0)
        {
            c.next = new ListNode(carry);
        }
        return n.next;
    }
}