Leetcode 12. Integer to Roman

题目：

Given an integer, convert it to a roman numeral.

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

思路：

1. 构造values,和numerals 数组保存 十进制数字 与罗马数字的对应

2. 遍历values数组，从最大开始，如果num比当前比较的数大，那么就减去当前的数（values[i]），

     并且将numerals[i]的值添加到结果的后面

3. 返回结果

源代码：

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