class Solution { public int romanToInt(String s) { s = s.replace("IV","a"); s = s.replace("IX","b"); s = s.replace("XL","c"); s = s.replace("XC","d"); s = s.replace("CD","e"); s = s.replace("CM","f"); int result = 0; for (int i=0; i<s.length(); i++) { result += which(s.charAt(i)); } return result; } public int which(char ch) { switch(ch) { 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; case 'a': return 4; case 'b': return 9; case 'c': return 40; case 'd': return 90; case 'e': return 400; case 'f': return 900; } return 0; } }将这个代码转化为C++

以下是将该代码转换为 C++ 的版本：

class Solution {
public:
    int romanToInt(string s) {
        s = replaceAll(s, "IV", "a");
        s = replaceAll(s, "IX", "b");
        s = replaceAll(s, "XL", "c");
        s = replaceAll(s, "XC", "d");
        s = replaceAll(s, "CD", "e");
        s = replaceAll(s, "CM", "f");

        int result = 0;
        for (int i = 0; i < s.length(); i++) {
            result += which(s[i]);
        }

        return result;
    }

private:
    int which(char ch) {
        switch(ch) {
            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;
            case 'a': return 4;
            case 'b': return 9;
            case 'c': return 40;
            case 'd': return 90;
            case 'e': return 400;
            case 'f': return 900;
        }
        return 0;
    }

    string replaceAll(string str, string oldStr, string newStr) {
        int pos = 0;
        while ((pos = str.find(oldStr, pos)) != string::npos) {
            str.replace(pos, oldStr.length(), newStr);
            pos += newStr.length();
        }
        return str;
    }
};

注意，在 C++ 中，字符串替换需要使用 `string::find()` 和 `string::replace()` 方法，因此需要单独定义一个 `replaceAll()` 函数来实现。