13. Roman to Integer

class Solution 
{
    int value(char str)
    {
        switch(str)
        {
            case 'I':
             return 1;
            case 'V':
             return 5;
            case 'X':
             return 10;
            case 'L':
             return 50;
            case 'C':
             return 100;
            case 'D':
             return 500;
            case 'M':
             return 1000;
        }
        return 0;
    }
    
    int romanToInt(String str)
    {
        int n=str.length();
        int p=0;
        int sum=0;
        
        for(int i=n-1;i>=0;i--)
        {
            char ch = str.charAt(i);
            if(value(ch)>=p)
                sum+=value(ch);
            else
                sum-=value(ch);
            p = value(ch);
        }
        return sum;
    }
}


/*

     for (int i = 0; i < n; i++)
    {
        if (s[i] == 'I')
        {
            if (s[i + 1] == 'V')
            {
                sum = sum + 4;
                i++;
            }
            else if (s[i + 1] == 'X')
            {
                sum = sum + 9;
                i++;
            }
            else
                sum = sum + 1;
        }
        else if (s[i] == 'V')
            sum = sum + 5;
        else if (s[i] == 'X')
        {
            {
                if (s[i + 1] == 'L')
                {
                    sum = sum + 40;
                    i++;
                }
                else if (s[i + 1] == 'C')
                {
                    sum = sum + 90;
                    i++;
                }
                else
                    sum = sum + 10;
            }
        }
        else if (s[i] == 'L')
            sum = sum + 50;
        else if (s[i] == 'C')
        {
            {
                if (s[i + 1] == 'D')
                {
                    sum = sum + 400;
                    i++;
                }
                else if (s[i + 1] == 'M')
                {
                    sum = sum + 900;
                    i++;
                }
                else
                    sum = sum + 100;
            }
        }
        else if (s[i] == 'D')
            sum = sum + 500;
        else if (s[i] == 'M')
            sum = sum + 1000;
        else
            return 0;
    }
    return sum;
}


*/