[leetcode]第2题

/**
 * 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 * pHead = new ListNode(0);
        ListNode * pCurrent = pHead;
        int overload = 0;
        while(l1 || l2 || overload)
        {
            int sum = ((l1 != NULL)?l1->val:0) + ((l2 != NULL)?l2->val:0);
            if(overload == 1)
            {
                sum = sum + 1;
            }
            if(10 <= sum)
            {
                sum%=10;
                overload = 1;
            }
            else
            {
                overload = 0;
            }
            pCurrent->next = new ListNode(sum);
            pCurrent = pCurrent->next;
            if(l1)
            {
                l1 = l1->next;
            }
            if(l2)
            {
                l2 = l2->next;
            }            
        }
        return pHead->next;
    }
};