求帮助：2. Add Two Numbers ，已疯，谢谢

自己运行：

提交以后：

代码：

 /**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
    struct ListNode *l,*p;
    l = (struct ListNode*)malloc(sizeof(struct ListNode));
    l->val = 0;
    l->next = NULL;
    p = l;
    int carry = 0;
    while(l1 || l2 || carry){
        if(l1){
            carry += l1->val;
            l1=l1->next;
        }
        if(l2){
            carry += l2->val;
            l2=l2->next;
        }

        p->next = (struct ListNode*)malloc(sizeof(struct ListNode));
        p = p->next;
        p->val = carry%10;
        carry /= 10;
    }
    return l->next;
}

为什么这个C++的就accepted。哪位能给点提示，谢谢

 class Solution {
public:
    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2) {
        ListNode *l = new ListNode(0), *p = l;
        int carry = 0;
        while(l1 || l2 || carry) {
            if(l1) {
                carry+=l1->val;
                l1 = l1->next;
            }
            if(l2) {
                carry+=l2->val;
                l2 = l2->next;
            }
            p->next = new ListNode(carry%10);
            carry /= 10;
            p = p->next;
        }
        return l->next;
    }
};

是这样的，C语言，最后指针的next应该指向NULL，这很重要