LeetCode-013罗马数字转整数

public int romanToInt(String s) {

    //罗马数字和整型之间的规则
    int[] nums = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
    String[] romans = {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};

    int res = 0;//结果
    int index = 0;//索引

    while (s.length() != 0){
        int temp = s.indexOf(romans[index]);//字符串开头对应的罗马数字位置
        if(temp == 0){//必须是开头
            res = res + nums[index];
            s = s.substring(romans[index].length());//缩短字符串直到为0结束循环
            if(index == 12){//或index==12，字符串后续只有IIIIII的情况跳出循环
                res = res + s.length();
                break;
            }
        }else{
            index++;
        }
    }

    return res;
}