[LeetCode]Reverse Words in a String

class Solution {public:    void reverseWords(string &s) {        string word;    stack<string> wordsStack;    stringstream ss(s);    while(ss>>word)    {    wordsStack.push(word);    }    string res = "";    bool first = true;    while(!wordsStack.empty())    {    if(!first)    res += " ";    res += wordsStack.top();    wordsStack.pop();    first = false;    }    s = res;    }};