Leetcode2兩數相加

/**
 * 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 nhead=new ListNode(-1);
        ListNode curr=nhead;
        int jinwei=0;
        ListNode first=l1;
        ListNode second=l2;
        while(first!=null || second!=null){
            int a=0,b=0;
            if(first!=null){
                a=first.val;
                first=first.next;
            }
            if(second!=null){
                b=second.val;
                second=second.next;
            }
            int sum=a+b+jinwei;
            jinwei=sum/10;
            curr.next=new ListNode(sum%10);
            curr=curr.next;
        }
        if(jinwei>0){
            curr.next=new ListNode(jinwei);
        }
        return nhead.next;
    }
}