<p>You are given a string <code>s</code> and an array of strings <code>words</code>. All the strings of <code>words</code> are of <strong>the same length</strong>.</p>

<p>A <strong>concatenated string</strong> is a string that exactly contains all the strings of any permutation of <code>words</code> concatenated.</p>

<ul>
	<li>For example, if <code>words = [&quot;ab&quot;,&quot;cd&quot;,&quot;ef&quot;]</code>, then <code>&quot;abcdef&quot;</code>, <code>&quot;abefcd&quot;</code>, <code>&quot;cdabef&quot;</code>, <code>&quot;cdefab&quot;</code>, <code>&quot;efabcd&quot;</code>, and <code>&quot;efcdab&quot;</code> are all concatenated strings. <code>&quot;acdbef&quot;</code> is not a concatenated string because it is not the concatenation of any permutation of <code>words</code>.</li>
</ul>

<p>Return an array of <em>the starting indices</em> of all the concatenated substrings in <code>s</code>. You can return the answer in <strong>any order</strong>.</p>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = &quot;barfoothefoobarman&quot;, words = [&quot;foo&quot;,&quot;bar&quot;]</span></p>

<p><strong>Output:</strong> <span class="example-io">[0,9]</span></p>

<p><strong>Explanation:</strong></p>

<p>The substring starting at 0 is <code>&quot;barfoo&quot;</code>. It is the concatenation of <code>[&quot;bar&quot;,&quot;foo&quot;]</code> which is a permutation of <code>words</code>.<br />
The substring starting at 9 is <code>&quot;foobar&quot;</code>. It is the concatenation of <code>[&quot;foo&quot;,&quot;bar&quot;]</code> which is a permutation of <code>words</code>.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = &quot;wordgoodgoodgoodbestword&quot;, words = [&quot;word&quot;,&quot;good&quot;,&quot;best&quot;,&quot;word&quot;]</span></p>

<p><strong>Output:</strong> <span class="example-io">[]</span></p>

<p><strong>Explanation:</strong></p>

<p>There is no concatenated substring.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s = &quot;barfoofoobarthefoobarman&quot;, words = [&quot;bar&quot;,&quot;foo&quot;,&quot;the&quot;]</span></p>

<p><strong>Output:</strong> <span class="example-io">[6,9,12]</span></p>

<p><strong>Explanation:</strong></p>

<p>The substring starting at 6 is <code>&quot;foobarthe&quot;</code>. It is the concatenation of <code>[&quot;foo&quot;,&quot;bar&quot;,&quot;the&quot;]</code>.<br />
The substring starting at 9 is <code>&quot;barthefoo&quot;</code>. It is the concatenation of <code>[&quot;bar&quot;,&quot;the&quot;,&quot;foo&quot;]</code>.<br />
The substring starting at 12 is <code>&quot;thefoobar&quot;</code>. It is the concatenation of <code>[&quot;the&quot;,&quot;foo&quot;,&quot;bar&quot;]</code>.</p>
</div>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 10<sup>4</sup></code></li>
	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
	<li><code>s</code> and <code>words[i]</code> consist of lowercase English letters.</li>
</ul>

class Solution {
public:
    vector<int> findSubstring(string s, vector<string>& words) {
        vector <int> start_indexes;
        unordered_map<string,int> master;
        for (int i=0;i<words.size();i++){
            master[words[i]]++;
        }
        int num_words = words.size(); // How many words there are in the array
        string word; 
        // Make it into a single word
        if (master.size()==1){
            // cout <<"Handling single vocab edge case" << endl;
            for (int i =0;i<num_words;i++){
                word += words[0];
            }
            words = {word};
            num_words = 1;
            // Now we have to fix master as well
            master.clear();
            master[words[0]]++;
        }
        unordered_map<string,int> copy(master);
        int word_size = words[0].length();
        int window_size = word_size * words.size();
        int s_len = s.length();
        if (s_len<window_size){
            return start_indexes;
        }
        int start_of_window = 0; // Start index of current window
        int end_of_window;
        int start_of_word;
        bool valid_window;
        // First loop for offset
        for (int offset=0;offset<word_size;offset++){ // start of first window
            // cout << "offset:" << offset << endl;
            for (int start_of_window = offset;start_of_window <= (s_len - window_size);start_of_window += word_size){
                copy = master;
                end_of_window = start_of_window + window_size;
                valid_window = true;
                // cout << "Start of window:" << start_of_window << " End of window:" << end_of_window << endl;
                for (int start_of_word = start_of_window;start_of_word <= (end_of_window - word_size);start_of_word += word_size){
                    // cout << "Start of word: " << start_of_word << endl;
                    word = s.substr(start_of_word,word_size);
                    if (copy[word]==0){
                        // cout << "\tInvalid word/ too many occurrences, word:" << word << endl;
                        valid_window = false;
                        break;
                    }
                    copy[word]--;
                }
                if (valid_window){
                    // cout << "Pushing start index: " << start_of_window << endl;    
                    start_indexes.push_back(start_of_window);   
                }
            }
        }
        return start_indexes;
    }
};
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