原题链接：

意思是给定两个存在链表中的数，输出和（同样存储在链表中）。

 

我的实现：

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */#include
     
      class Solution {public:    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {        stack
      
        result_stack;        ListNode* result_list = NULL;        int val, carry;                carry = 0;                while(l1 != NULL || l2 != NULL || carry != 0) {            int l1_num, l2_num, sum;                        if (l1 == NULL) {                l1_num = 0;            } else {                l1_num = l1->val;                l1 = l1->next;            }                        if (l2 == NULL) {                l2_num = 0;            } else {                l2_num = l2->val;                l2 = l2->next;            }                        sum = l1_num + l2_num + carry;            val = sum % 10;            carry = sum / 10;                        result_stack.push(val);        }                while(!result_stack.empty()) {            ListNode* result_node = new ListNode(result_stack.top());                        result_node->next = result_list;            result_list = result_node;                        result_stack.pop();        }                return result_list;    }};
      
     

主要是注意进位，结果的保存。不要像我一样这么麻烦地保存结果的，直接在运算时构建结果链表即可。