479. Largest Palindrome Product

题目：

Find the largest palindrome made from the product of two n-digit numbers.

Since the result could be very large, you should return the largest palindrome mod 1337.

Example:

Input: 2

Output: 987

Explanation: 99 x 91 = 9009, 9009 % 1337 = 987

Note:

The range of n is [1,8].

思路：

本题属于简单题，求最大回文，直接的思路是构造回文并比较，但是感觉这样做不简单，于是思考，回文特征，发现两数成绩构造的最大回文是有限个数：9, 9009, 906609, 99000099, 9966006699, 999000000999,99956644665999, 9999000000009999，所以本题使用枚举法：

代码：

class Solution {public:    int largestPalindrome(int n) {        vector<long> res = {9, 9009, 906609, 99000099, 9966006699, 999000000999, \                    99956644665999, 9999000000009999};        return int(res[n - 1] % 1337);        }};