[leetcode]Add Two Numbers

You are given two non-empty linked lists representing two non-negative integers. 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.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

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* l3 = new ListNode(0);
ListNode* ptr = l3;
int tmp = 0;
while(1){
if(l1 != NULL ){
tmp += l1->val ;
l1 = l1->next;
}
if( l2 != NULL){
tmp += l2->val;
l2 = l2->next;
}
ptr->val = tmp%10;
tmp /= 10;
if(l1 != NULL || l2 !=NULL || tmp != 0){
ptr->next = new ListNode(0);
ptr = ptr->next;
}
else
break;
}

return l3;
}
};