LEETCODE: 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".

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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) {        // Skip the spaces on the left        int pos = 0;        for(; pos < s.length(); pos ++) {            if(s[pos] != ' ')                break;        }        string result;        string word;        for(; pos < s.length(); pos ++) {            // If is space, check if we have word. Have, record it. Not have, skip.            if(s[pos] == ' ') {                if(word.length() != 0) {                    if(!result.empty())                        result = " " + result;                    result = word + result;                    word.clear();                }            }            else {                word += s[pos];            }        }                if(word != "") {            if(!result.empty())                result = " " + result;            result = word + result;        }                if(result.length() != 0) {            if(result[0] == ' ') {                s = result.substr(1);                return;            }        }        s = result;    }};