romanToInt.java

import java.util.Scanner;

class Solution {
    public int romanToInt(String s) {
        int res = 0;
		for (int i = 0; i < s.length(); i++) {	
			int s1 = value(s.charAt(i));
			if (i + 1 < s.length()) {
				int s2 = value(s.charAt(i + 1));
				if (s1 >= s2) {
					res = res + s1;
				}
				else {	
					res = res + s2 - s1;
					i++;
				}
			}
			else {
				res = res + s1;
			}
		}
		return res;
    }
    int value(char r)
	{
		if (r == 'I')
			return 1;
		if (r == 'V')
			return 5;
		if (r == 'X')
			return 10;
		if (r == 'L')
			return 50;
		if (r == 'C')
			return 100;
		if (r == 'D')
			return 500;
		if (r == 'M')
			return 1000;
		return -1;
	}
	public static void main(String args[]){
		Solution ob=new Solution();
		Scanner sc=new Scanner(System.in);
		System.out.println("Enter a roman number");
		String x=sc.nextLine();
		int a=ob.romanToInt(x);
		System.out.println(a);

	}
}