<p>Given an input string <code>s</code>, reverse the order of the <strong>words</strong>.</p>

<p>A <strong>word</strong> is defined as a sequence of non-space characters. The <strong>words</strong> in <code>s</code> will be separated by at least one space.</p>

<p>Return <em>a string of the words in reverse order concatenated by a single space.</em></p>

<p><b>Note</b> that <code>s</code> may contain leading or trailing spaces or multiple spaces between two words. The returned string should only have a single space separating the words. Do not include any extra spaces.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;the sky is blue&quot;
<strong>Output:</strong> &quot;blue is sky the&quot;
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;  hello world  &quot;
<strong>Output:</strong> &quot;world hello&quot;
<strong>Explanation:</strong> Your reversed string should not contain leading or trailing spaces.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;a good   example&quot;
<strong>Output:</strong> &quot;example good a&quot;
<strong>Explanation:</strong> You need to reduce multiple spaces between two words to a single space in the reversed string.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
	<li><code>s</code> contains English letters (upper-case and lower-case), digits, and spaces <code>&#39; &#39;</code>.</li>
	<li>There is <strong>at least one</strong> word in <code>s</code>.</li>
</ul>

<p>&nbsp;</p>
<p><b data-stringify-type="bold">Follow-up:&nbsp;</b>If the string data type is mutable in your language, can&nbsp;you solve it&nbsp;<b data-stringify-type="bold">in-place</b>&nbsp;with&nbsp;<code data-stringify-type="code">O(1)</code>&nbsp;extra space?</p>

#include <string.h>

class Solution {
public:
    string reverseWords(string s) {
        std::vector<string> vec {};
        int head = 0;
        int tail = s.size()-1;
        char  space = ' '; 
        while (head < tail){
            if(s[head] == ' '){
                head ++;
            }
            else{
                break;
            }
        }

        for(int i = 0; i<= tail; i++){
            cout << s[i] ;
        }
        cout <<"\n";

        while (tail > head){
            cout << "tail: "<< tail;
            cout <<"\nchar: " << s[tail] << " comparision: " << (isalnum(s[tail])) <<"\n";

            if(s[tail] == ' '){
                cout << "trailing space, reduce tail";
                cout << "next is "<< s[tail-1] <<"\n";
                tail --;
            }
            else if (isalnum(s[tail])!=8){
                cout << "weird char, reduce tail";
                cout << "next is "<< s[tail-1] <<"\n";
                tail --;
            // cout << "\n";
            }
            else{
                 break;
            };
        }

        cout << "head :" << head;
        string word = "";
        for (int i=head; i <= tail; i++){
            cout <<s[i];
            if (s[i] == ' '){
                vec.insert(vec.begin(),word);
                word.clear();
            }
            else word += s[i];
        }
        vec.insert(vec.begin(),word);
        cout <<"\nWord--"<<word<<"--" <<"\n";

        for (int i = 1; i < vec.size(); i++){
            if (vec[i] != ""){
                word += " ";
                word += vec[i];
            }
        }
        return word;
    }
};
14000