leetcode-2. Add Two Numbers

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https://leetcode.com/problems/add-two-numbers/#/description
单链表问题，有表头，注意Java中链表的写法，自定义一个类，描述每个链表的节点
public class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}

问题描述：
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

代码如下

public class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        ListNode prev=new ListNode(0);        ListNode head=prev;        int c=0;        while(l1!=null || l2!=null || c!=0 )        {            ListNode cur=new ListNode(0);            int sum=((l1==null)? 0 : l1.val )+((l2==null)?0: l2.val )+c;            cur.val=sum%10;            c=sum/10;            prev.next=cur;            prev=cur;            l1=(l1==null)?l1:l1.next;            l2=(l2==null)?l2:l2.next;        }        return head.next;    }}

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