LeetCodeOJ--Reverse Words in a String

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.

C++版本：

class Solution {
public:
    void reverseWords(string &s) {
	string rs;
	for (int i = s.length()-1; i >= 0; )
	{
		while (i >= 0 && s[i] == ' ') {i--;}
		if (i < 0) {break;}
		if (!rs.empty()) {rs.push_back(' ');}
		string t;
		while (i >= 0 && s[i] != ' ') {t.push_back(s[i--]);}
		reverse(t.begin(), t.end());
		rs.append(t);
	}
	s = rs;
    }
};