【LeetCode】002 Add Two Numbers

题目：

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

题解：

　　

 /**
  * 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 dummy(-);
         ListNode* pre = &dummy;
         int carry = ;

         while (l1 || l2) {
             int addend1 = l1 == nullptr ?  : l1->val;
             int addend2 = l2 == nullptr ?  : l2->val;
             int sum = addend1 + addend2 + carry;
             ListNode* cur = new ListNode(sum % );
             pre->next = cur;
             pre = pre->next;
             carry = sum / ;

             if (l1)
                 l1 = l1->next;
             if (l2)
                 l2 = l2->next;
         }

         if (carry) {
             ListNode* cur = new ListNode(carry);
             pre->next = cur;
         }
         return dummy.next;
     }
 };