Roman to Integer

Given a roman numeral, convert it to an integer.

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

自己写的代码第一次没有AC，超时。第二遍就莫名其妙通过了

public int romanToInt(String s){
        int result = 0;
        char[] array = s.toCharArray();
        Map<Character,Integer> roman = new HashMap<>();
        roman.put('I',1);
        roman.put('V',5);
        roman.put('X',10);
        roman.put('L',50);
        roman.put('C',100);
        roman.put('D',500);
        roman.put('M',1000);
        if (array.length==1){
            return roman.get(array[0]);
        }
        for (int current = 1; current < array.length; current++) {
            int pre = current-1;
            int preint = roman.get(array[pre]);
            int currentint = roman.get(array[current]);
            if (preint>=currentint){
                result+=preint;
            }
            else{
                result-=preint;
            }
        }
        result+=roman.get(array[array.length-1]);
        return result;
    }

附上相似代码

public static int romanToInt(String s) {
	if (s == null || s.length() == 0)
		return -1;
	HashMap<Character, Integer> map = new HashMap<Character, Integer>();
	map.put('I', 1);
	map.put('V', 5);
	map.put('X', 10);
	map.put('L', 50);
	map.put('C', 100);
	map.put('D', 500);
	map.put('M', 1000);
	int len = s.length(), result = map.get(s.charAt(len - 1));
	for (int i = len - 2; i >= 0; i--) {
		if (map.get(s.charAt(i)) >= map.get(s.charAt(i + 1)))
			result += map.get(s.charAt(i));
		else
			result -= map.get(s.charAt(i));
	}
	return result;
}