[leetcode] add two numbers（大数据加法链表版）

Add Two Numbers

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

题意：输入两个链表，对应位相加，并且进位到下一位。

/**
* 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 *ans = new ListNode(0), *p = ans;
int cur = 0;
while(l1 != NULL || l2 != NULL || cur)
{
p->val = (l1 ? l1->val : 0) + (l2 ? l2->val : 0) + cur;
cur = p->val / 10;
p->val %= 10;
if(l1) l1 = l1->next;
if(l2) l2 = l2->next;
if(l1 || l2 || cur)
p->next = new ListNode(0);
p = p->next;
}
return ans;
}
};