418.Integer to Roman-整数转罗马数字（中等题）

整数转罗马数字

1. 题目

   给定一个整数，将其转换成罗马数字。
   返回的结果要求在1-3999的范围内。

2. 说明

   什么是 罗马数字?
   https://en.wikipedia.org/wiki/Roman_numerals
   https://zh.wikipedia.org/wiki/%E7%BD%97%E9%A9%AC%E6%95%B0%E5%AD%97
   http://baike.baidu.com/view/42061.htm

3. 样例

   4 -> IV
   12 -> XII
   21 -> XXI
   99 -> XCIX
   更多案例，请戳 http://literacy.kent.edu/Minigrants/Cinci/romanchart.htm

4. 题解

   把1-9个1,1-9个10,1-9个100和1-3个1000准备好，后直接查表即可。

public class Solution {
    /**
     * @param n The integer
     * @return Roman representation
     */
    public String intToRoman(int n) {
        String roman[][]={
            {"","I","II","III","IV","V","VI","VII","VIII","IX"},
            {"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"},
            {"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"},
            {"","M","MM","MMM"}
        };
        StringBuilder res = new StringBuilder();
        res.append(roman[3][n / 1000 % 10]);
        res.append(roman[2][n / 100 % 10]);
        res.append(roman[1][n / 10 % 10]);
        res.append(roman[0][n % 10]);
        return res.toString();
    }
}

Last Update 2016.11.17