class Solution {
public:
    /*
     * @param s: A string
     * @return: A string
     */
    string reverseWords(string &s) {
        // write your code here
        string res;
        if(s.empty())
            return s;
        reverse(s.begin(),s.end());//将整个字符串反转
   
        char *stoc= const_cast<char*>(s.data());//将string转char*。先将string转const char*再转char*
        char *tmpStr = strtok(stoc," ");
        while (tmpStr != NULL) //通过空格将字符串分割成多个单词
        {
            if(tmpStr!=" ")
            {
                string temp=(string)tmpStr;
                reverse(temp.begin(),temp.end());//再将单词反转
                res.append(" ");
                res.append(temp);//res最后的格式：空格+单词A+空格+单词B
            }
            tmpStr = strtok(NULL, " ");
        }
        
        //删除开头的空格
        if(!res.empty())
        {
            res.erase(0,res.find_first_not_of(" "));
        }
        return res;
    }
};