解决思路

哈希表

  public String intToRoman(int num) {
        int[] values = {1000,900,500,400,100,90,50,40,10,9,5,4,1};
        String[] strs = {"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
        StringBuilder res = new StringBuilder();
        for(int i = 0;i < values.length;i++){
            int a = num / values[i];
            if (a == 0)
                continue;
            for(int j = a;j > 0;j--)
                res.append(strs[i]);
            num -= (a * values[i]);
            if (num == 0)
                break;
        }
        return res.toString();
    }