LeetCode OJ 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.

class Solution {public:    void reverseWords(string &s) {        bool first = true;        string temp = " ";        temp += s + " ";        s.clear();        for (int i = temp.size() - 1; i > 0;) {            if (temp[i] == ' ' && temp[i - 1] != ' ') {                int j;                for (j = i - 1; j > 0; j--) {                    if (temp[j] != ' ' && temp[j - 1] == ' ') {                        if (!first) {                            s += " ";                        }                        first = false;                        s += temp.substr(j, i - j);                        break;                    }                }                i = j - 1;            } else {                i--;            }        }    }};