LeetCode[Math]: Integer to Roman

Given an integer, convert it to a roman numeral.

Input is guaranteed to be within the range from 1 to 3999.

欲了解罗马数字的拼写规则请参考：http://blog.csdn.net/chfe007/article/details/44037079

C++代码实现如下：

    string intToRoman(int num) {
        static const int ints[13] = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
        static const string romans[13] = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" };

        for (int i = 0; i < 13; ++i) {
            if (num >= ints[i])
                return string(romans[i]) + intToRoman(num - ints[i]);
        }

        return "";
    }

时间性能如下：