<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 {
private:
    int concateSize;
    int wordSize;
    map<string, int> wordCount;
    string s;

public:
    vector<int> findSubstring(string s, vector<string>& words) {
        this->s = s;
        wordSize = words[0].size();
        int wordsSize = words.size();
        concateSize = wordSize * wordsSize;
        if (concateSize > s.length()) {
            return {};
        }
        set<char> alphaInWords;
        for (string word : words) {
            if (wordCount.find(word) == wordCount.end()) {
                wordCount[word] = 0;
            }
            for (char c : word) {
                alphaInWords.insert(c);
            }
            wordCount[word]++;
        }
        vector<int> ret;
        int maxI = s.length() - concateSize;
        bool onlyOneChar = alphaInWords.size() == 1;
        int i = 0;
        for (i; i <= maxI; i++) {
            map<string, int> copyWordCount = wordCount;
            bool _isConcat = isConcate(i, copyWordCount);
            if (_isConcat) {
                ret.push_back(i);
                int j = 0;
                while (i + j <= maxI && s[i + j] == s[i + concateSize + j]) {
                    if (onlyOneChar) {
                        ret.push_back(i + j + 1);
                    } else if (j % wordSize == wordSize - 1) {
                        ret.push_back(i + j + 1);
                    }
                    j++;
                }
                i = i + j;
            }
        }
        return ret;
    }

    bool isConcate(int start, map<string, int>& _wordCount) {
        string curr = "";
        queue<string> q;
        for (int i = 0; i < concateSize; i++) {
            if (i != 0 && i % wordSize == 0) {
                if (_wordCount.find(curr) == _wordCount.end()) {
                    return false;
                }
                _wordCount[curr]--;
                if (_wordCount[curr] < 0) {
                    return false;
                }
                curr = "";
            }
            curr += s[start + i];
        }
        if (_wordCount.find(curr) == _wordCount.end()) {
            return false;
        }
        _wordCount[curr]--;
        if (_wordCount[curr] < 0) {
            return false;
        }
        return true;
    }
};
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