class Solution {
public:
    /**
     * 反转字符串
     * @param str string字符串 
     * @return string字符串
     */
    string solve(string str) {
        int start;
        int end;
        int i;
        string result="";
        if(str.length()==0){
            result="";
        }
        else{
            for(i=str.length()-1;i>=0;i--){
                result+=str[i]; 
            }
        }
        return result;// write code here
    }
};