/**
* 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) {
int carry = 0;
ListNode* dummy = new ListNode(0);
ListNode* p = dummy;
while (l1 || l2 || carry) {
int sum = 0;
sum += l1 ? l1 -> val : 0;
sum += l2 ? l2 -> val : 0;
sum += carry;
p -> next = new ListNode(sum % 10);
p = p -> next;
carry = sum / 10;
if (l1) l1 = l1 -> next;
if (l2) l2 = l2 -> next;
}
return dummy -> next;
}
};