leetcode第13题罗马数字转整数

这道题目有些细节需要注意：
1、HASHMAP最好给object指定类型
2、replace("a","b")如果转换，会将转换后的值生成新的引用。旧引用不会改变

比如下列代码：

string a = "aabbc";
a.replace("c","f");
system.out.println(a);//此刻结果是aabbc，并没有发生改变，
a=a.replace("c","f");//正解~

题目答案：

class Solution {
    public int romanToInt(String s) {
        HashMap<String,Integer> romaNum = new HashMap<String,Integer>(14);
        romaNum.put("A",4);
        romaNum.put("B",9);
        romaNum.put("E",40);
        romaNum.put("F",90);
        romaNum.put("G",400);
        romaNum.put("H",900);
        romaNum.put("I",1);
        romaNum.put("V",5);
        romaNum.put("X",10);
        romaNum.put("L",50);
        romaNum.put("C",100);
        romaNum.put("D",500);
        romaNum.put("M",1000);
        
        String new_s = s.replace("IV","A").replace("IX","B").replace("XL","E").replace("XC","F").replace("CD","G").replace("CM","H");

        int sNum= 0;
        for(int i=0;i<new_s.length();i++){
            int a=romaNum.get(new_s.charAt(i)+"");
            sNum = sNum + a;
        }

    return sNum;
    }
}
```