13. Roman to Integer

//O(n) time and space
class Solution {
    public int romanToInt(String s) {
        int[] digits = new int[s.length()];
        for(int i=0;i<s.length();i++){
            switch(s.charAt(i)){
                case 'I':
                digits[i] = 1;
                break;
                case 'V':
                digits[i] = 5;
                break;
                case 'X':
                digits[i] = 10;
                break;
                case 'L':
                digits[i] = 50;
                break;
                case 'C':
                digits[i] = 100;
                break;
                case 'D':
                digits[i] = 500;
                break;
                case 'M':
                digits[i] = 1000;
                break;
            }
        }
        int result = 0;
        for(int i=0;i<digits.length-1;i++){
            if(digits[i]<digits[i+1])
                result-=digits[i];
            else
                result+=digits[i];
        }
        return result+digits[s.length()-1];
    }
}