LeetCode——Add Two Numbers

Question:
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
Solution:

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     NodeList *next;
 6  *     NodeList(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode *addTwoNumbers(ListNode *head1, ListNode *head2) {
12         int n1=0,n2=0;
13     ListNode *ptr1=head1,*ptr2=head2;
14     while(ptr1!=NULL)
15     {
16         n1++;
17         ptr1=ptr1->next;
18     }
19     while(ptr2!=NULL)
20     {
21         n2++;
22         ptr2=ptr2->next;
23     }
24     vector<int> sum;
25     int temp;
26     ListNode *head_long,*head_short;
27     if(n1>=n2)
28     {
29         head_long=head1;
30         head_short=head2;
31     }
32     else
33     {
34         head_long=head2;
35         head_short=head1;
36     }
37     /////
38         ListNode *pt1=head_long,*pt2=head_short;
39         while(pt2!=NULL)
40         {
41             temp=pt1->val+pt2->val;
42             if(temp>=10)
43             {
44                 sum.push_back(temp%10);
45                 if(pt1->next==NULL)
46                 {
47                     sum.push_back(1);
48                 }
49                 else
50                     pt1->next->val+=1;
51             }
52             else
53                 sum.push_back(temp);
54             pt1=pt1->next;pt2=pt2->next;
55         }
56         while(pt1!=NULL)
57         {
58             temp=pt1->val;
59             if(temp>=10)
60             {
61                 sum.push_back(temp%10);
62                 if(pt1->next==NULL)
63                 {
64                     sum.push_back(1);
65                 }
66                 else
67                     pt1->next->val+=1;
68             }
69             else
70                 sum.push_back(temp);
71             pt1=pt1->next;
72         }
73         ListNode *result=new ListNode(0);
74         ListNode *rp=new ListNode(0);
75         rp=result;
76         ListNode *rq;
77 
78         for(vector<int>::iterator iter=sum.begin();iter!=sum.end();iter++)
79         {
80             rq=new ListNode(0);
81             rq->val=*iter;
82             rp->next=rq;
83             rp=rq;
84         }
85 
86         rp->next=NULL;
87         result=result->next;  
88         return result;
89     }
90 };