<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> letters(26, 0);
        vector<pair<string,int>> mots;
        int num = words.size(), m = s.length();
        int total = 0;
        for (int i = 0; i < num; i++){
            for (int j = 0, len = words[i].length(); j < len; j++){
                letters[words[i][j] - 'a']++;
                total++;
            }
            bool found = false;
            for (int j = 0, len = mots.size(); j < len; j++){
                if (mots[j].first == words[i]){
                    mots[j].second++;
                    found = true;
                    break;
                }
            }
            if (!found) mots.push_back({words[i], 1});
        }
        int n = mots.size();
        if (total > m) return {};
        vector<int> current(26, 0);
        vector<int> ans;
        for (int i = 0; i < total-1; i++) current[s[i] - 'a']++;
        for (int i = 0; i <= m-total; i++){
            if (i != 0) current[s[i-1] - 'a']--;
            current[s[i+total-1] - 'a']++;
            if (current != letters) continue;
            vector<int> counts(num, 0);
            vector<pair<string,int>> motSave = mots; 
            int ind = 0, cind = 0;
            while (ind >= 0){
                if (cind == total){
                    ans.push_back(i);
                    break;
                }
                if (counts[ind] >= n){
                    counts[ind] = 0;
                    ind--;
                    if (ind >= 0){
                        cind -= mots[counts[ind]].first.length();
                        mots[counts[ind]].second++;
                        counts[ind]++;
                    }
                }
                else if (mots[counts[ind]].second && mots[counts[ind]].first == string(s.begin()+i+cind,s.begin()+i+cind+mots[counts[ind]].first.length())){
                    cind += mots[counts[ind]].first.length();
                    mots[counts[ind]].second--;
                    ind++;
                }
                else counts[ind]++;
            }
            mots = motSave;
        }
        return ans;
    }
};
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