leetcode---add-two-numbers---链表

You are given two linked lists representing two non-negative numbers. 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.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

/** * 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)     {        if(!l1)            return l2;        if(!l2)            return l1;        ListNode *result = new ListNode(0);        ListNode *pResult = result;        ListNode *pl1 = l1, *pl2 = l2;        while(pl1 && pl2)        {            ListNode *next = new ListNode(pl1->val + pl2->val);            pResult->next = next;            pResult = pResult->next;            pl1 = pl1->next;            pl2 = pl2->next;        }        if(pl1)            pResult->next = pl1;        if(pl2)            pResult->next = pl2;        pResult = result->next;        int c = 0;        ListNode *pre = NULL;        while(pResult)        {            pResult->val += c;            c = pResult->val / 10;            pResult->val %= 10;            pre = pResult;            pResult = pResult->next;        }        if(c > 0)        {            pre->next = new ListNode(c);        }        return result->next;    }};