roman_to_numeral.java

package dynamic_programming;

public class roman_to_numeral {

    public static int decodeSingle(char letter) {
        switch (letter) {
            case 'M':
                return 1000;
            case 'D':
                return 500;
            case 'C':
                return 100;
            case 'L':
                return 50;
            case 'X':
                return 10;
            case 'V':
                return 5;
            case 'I':
                return 1;
            default:
                return 0;
        }
    }

    public static int decode(String roman) {
        int result = 0,i;
        for ( i = 0; i < roman.length() - 1; i++) {
            if (decodeSingle(roman.charAt(i)) < decodeSingle(roman.charAt(i + 1))) {
                result -= decodeSingle(roman.charAt(i));
            } else {
                result += decodeSingle(roman.charAt(i));
            }
        }
        result += decodeSingle(roman.charAt(i));
        return result;
    }

    public static void main(String[] args) {
        String str = "MIV";
        System.out.println(decode(str));
        String str1 = "XXX";
        System.out.println(decode(str1));
    }
}