leetcode— Integer to Roman

Given an integer, convert it to a roman numeral.

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

class Solution {
    public String intToRoman(int num) {
        String[] s1 = {"","I","II","III","IV","V","VI","VII","VIII","IX"};
        String[] s2 = {"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"};
        String[] s3 = {"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"};
        String[] s4 = {"","M","MM","MMM"};
        String s = s4[num/1000]+s3[num/100%10]+s2[num/10%10]+s1[num%10];
        return s;
    }
}

**思路：記住幾個最主要的數字的對應關係
基本字符：
　　I、V、X、L、C、D、M
　　相應的阿拉伯數字表示爲：
　　1．5、10、50、100、500、1000**