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:

 /**
  * Definition for singly-linked list.
  * struct ListNode {
  *     int val;
  *     NodeList *next;
  *     NodeList(int x) : val(x), next(NULL) {}
  * };
  */
 class Solution {
 public:
     ListNode *addTwoNumbers(ListNode *head1, ListNode *head2) {
         int n1=,n2=;
     ListNode *ptr1=head1,*ptr2=head2;
     while(ptr1!=NULL)
     {
         n1++;
         ptr1=ptr1->next;
     }
     while(ptr2!=NULL)
     {
         n2++;
         ptr2=ptr2->next;
     }
     vector<int> sum;
     int temp;
     ListNode *head_long,*head_short;
     if(n1>=n2)
     {
         head_long=head1;
         head_short=head2;
     }
     else
     {
         head_long=head2;
         head_short=head1;
     }
     /////
         ListNode *pt1=head_long,*pt2=head_short;
         while(pt2!=NULL)
         {
             temp=pt1->val+pt2->val;
             if(temp>=)
             {
                 sum.push_back(temp%);
                 if(pt1->next==NULL)
                 {
                     sum.push_back();
                 }
                 else
                     pt1->next->val+=;
             }
             else
                 sum.push_back(temp);
             pt1=pt1->next;pt2=pt2->next;
         }
         while(pt1!=NULL)
         {
             temp=pt1->val;
             if(temp>=)
             {
                 sum.push_back(temp%);
                 if(pt1->next==NULL)
                 {
                     sum.push_back();
                 }
                 else
                     pt1->next->val+=;
             }
             else
                 sum.push_back(temp);
             pt1=pt1->next;
         }
         ListNode *result=new ListNode();
         ListNode *rp=new ListNode();
         rp=result;
         ListNode *rq;

         for(vector<int>::iterator iter=sum.begin();iter!=sum.end();iter++)
         {
             rq=new ListNode();
             rq->val=*iter;
             rp->next=rq;
             rp=rq;
         }

         rp->next=NULL;
         result=result->next;
         return result;
     }
 };