Given an input string, reverse the string word by word.

For example,
Given s = " the sky is blue ",
return "blue is sky the".

click to show clarification.

Clarification:
What constitutes a word?
A sequence of non-space characters constitutes a word.
Could the input string contain leading or trailing spaces?
Yes. However, your reversed string should not contain leading or trailing spaces.
How about multiple spaces between two words?
Reduce them to a single space in the reversed string.

用stringstream读到流中忽略空格，在重新赋给一个新的string,添加空格

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

google了python的代码。。。竟然就一行。。。。我勒个去。

class Solution:    # @param s, a string    # @return a string    def reverseWords(self, s):        return ‘ ‘.join([word[::-1] for word in s[::-1].split()])