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?

這道題讓我們翻轉一個字串中的單詞，跟之前那題Reverse Words in a String沒有區別，由於之前那道題我們就是用in-place的方法做的，而這道題反而更簡化了題目，因為不考慮首尾空格了和單詞之間的多空格了，方法還是很簡單，先把每個單詞翻轉一遍，再把整個字串翻轉一遍，或者也可以調換個順序，先翻轉整個字串，再翻轉每個單詞，參見程式碼如下：

class Solution {
public:
    void reverseWords(string &s) {
        int left = 0;
        for (int i = 0; i <= s.size(); ++i) {
            
 
if (i == s.size() || s[i] == ' ') {
                reverse(s, left, i - 1);
                left = i + 1;
            }
        }
        reverse(s, 0, s.size() - 1);
    }
    void reverse(string &s, int left, int right) {
        while (left < right) {
            char t = s[left];
            s[left] 
 
= s[right];
            s[right] = t;
            ++left; --right;
        }
    }
};

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