Add Two Numbers

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

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution{
public:
ListNode* addTwoNumbers(ListNode* l1,ListNode* l2){

ListNode* head=new ListNode(-1);
ListNode* cur = head;
int carry = 0;
int val = 0;
while(l1 && l2){
val = l1->val + l2->val+carry;
carry = val / 10;
val = val % 10;
cur->next = new ListNode(val);
cur = cur->next;
l1 = l1->next;
l2 = l2->next;
}

if(l1 || l2){
ListNode *p = l1? l1 : l2;
while(p){
val = p->val + carry;
carry = val / 10;
val = val % 10;
cur->next = new ListNode(val);
cur = cur->next;
p= p->next;
}
}

if(carry)
cur->next = new ListNode(carry);
return head->next;
}
};