Reverse Words in a String II -- LeetCode

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?

思路：这题比另一个reverse words要简单，因为不存在多余空格的问题。

因此in-place方法很简单，先把整个字符串反转，然后依次把字符串中的每个单词再反转一次。

 class Solution {
 public:
     void reverseWords(string &s) {
         int l = , r = s.size() - ;
         while (l < r)
             swap(s[l++], s[r--]);
         for (int i = , n = s.size(); i < n;)
         {
             for (r = i + ; r < n && s[r] != ' '; r++);
             l = i, r--;
             i = r + ;
             while (l < r)
                 swap(s[l++], s[r--]);
         }
     }
 };