186 Reverse Words In a String II

来源：Leetcode

原帖：https://leetcode.com/problems/reverse-words-in-a-string-ii/

题目：
Given an input string, reverse the string word by word. A word is defined as a sequence of non-space characters. The input string does not contain leading or trailing spaces and the words are always separated by a single space.
For example,
Given s = "the sky is blue", return "blue is sky the".
Could you do it in-place without allocating extra space?

代码：

 class Solution {  
 public:  
   // in-place reverse  
   void reverseWords(string &s) {  
     reverse(s.begin(), s.end());  
     int end = 0;  
     for (int i = 0; i < s.size(); ++i) {  
       if (s[i] == ' ') continue;  
       if (end != 0) s[end++] = ' ';  
       int l = i, h = i;  
       while (i != s.size() && s[i] != ' ') {  
         h++; i++;  
       }  
       reverse(s.begin() + l, s.begin() + h);  
       for (int j = l; j < h; ++j) {  
         s[end++] = s[j];  
       }  
     }  
     s.resize(end);    
   }  
 };