Leetcode12 Integer to Roman

Roman to Integer

Given an integer, convert it to a roman numeral.
Input is guaranteed to be within the range from 1 to 3999.

解题思路：
其中每两个阶段的之间有一个减法的表示，比如 900=CM， C 写在 M 前面表示 M-C。
所以映射关系应该是

string symbol[]={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};    
int value[]=    {1000,900,500,400, 100, 90,  50, 40,  10, 9,   5,  4,   1};   

然后就是贪心的做法，每次选择能表示的最大值，把对应的字符串连起来。

    public String intToRoman(int num) {
        StringBuilder sb = new StringBuilder(); // result
        String[] str = new String[] { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I" };
        int value[]=    {1000,900,500,400, 100, 90,  50, 40,  10, 9, 5, 4, 1};   

        for(int i=0; num!=0; ++i){
             while(num >= value[i]){
                 num = num - value[i];
                 sb.append(str[i]);
             }
         }
        return sb.toString();
        }