intToRoman.java

/*


Given an integer, convert it to a roman numeral, and return a string corresponding to its roman numeral version

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

Example :

Input : 5
Return : "V"

Input : 14
Return : "XIV"

*/

public String intToRoman(int a) {
        if(a==0)
            return "";
        HashMap<Integer, String> map = new HashMap<Integer, String>();
        map.put(1, "I");
        map.put(4, "IV");
        map.put(5, "V");
        map.put(9, "IX");
        map.put(10, "X");
        map.put(40, "XL");
        map.put(50, "L");
        map.put(90, "XC");
        map.put(100, "C");
        map.put(400, "CD");
        map.put(500, "D");
        map.put(900, "CM");
        map.put(1000, "M");

        String re = "";
        int[] bases = { 1000,
                900,
                500,
                400,
                100,
                90,
                50,
                40,
                10,
                9,
                5,
                4,
                1};
        int i =0;
        while(i<bases.length)
        {
            if(a>0 && a>=bases[i])
            {
               re+=map.get(bases[i]);
               a-=bases[i];
            }
            else
                i++;
        }
        return re;
    }