【leetcode】2. Add Two Numbers

@requires_authorization@author johnsondu@create_time 2015.7.15 14:54@url [add two numbers](https://leetcode.com/problems/add-two-numbers/)/** *    链表模拟大数相加 *    时间复杂度: O(n) *    空间复杂度: O(n) *//** * 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 *head = new ListNode(0);        ListNode *cur = head;        int carry = 0;        while(l1 || l2 || carry){            int tmp = carry;            if(l1 != NULL) {                tmp = tmp + l1->val;                l1 = l1->next;            }            if(l2 != NULL) {                tmp = tmp + l2->val;                l2 = l2->next;            }            carry = tmp / 10;            ListNode *node = new ListNode(tmp % 10);            cur->next = node;            cur = cur->next;        }        return head->next;    }};