LeetCode-2.两数相加（Add Two Number）

/**
 * 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* L = new ListNode(0);
        ListNode* temp = L;
        int sum = 0;
        while(l1 || l2) {
        	if(l1) {
        		sum += l1->val;
        		l1 = l1->next; 
        	}
        	if(l2) {
        		sum += l2->val;
        		l2 = l2->next;
        	}
        	temp->next = new ListNode(sum % 10);
        	sum /= 10;
        	temp = temp->next;
        }
        if(sum){
        	temp->next = new ListNode(1);
        }
        return L->next;
    }
};