9.迴文數（留意兩個字符串處理函數）

string zheng = to_string(x);
reverse(fan.begin(), fan.end());

class Solution {
public:
    bool isPalindrome(int x) {
        string zheng = to_string(x);
        string fan = zheng;
        reverse(fan.begin(), fan.end());
        if (zheng == fan) return true;
        else return false;
    }
};