<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) {
        unordered_map<string, int> s_set;
        unordered_map<string, int> checkdup;
        unordered_set<int> result_set;
        vector<int> result;
        int step = words[0].size();
        //cout<<words.size()<<endl;
        //cout<<s.size() - step*words.size()<<endl;
        if (s.size() < step* words.size())
            return result;
        for (string w : words) {
            if(s_set.contains(w))
                s_set[w] += 1;
            else
                s_set.insert({w,1});
        }
        
        int count = 0;
        for (int w_idx = 0; w_idx < step; w_idx++) {
        for (int i = w_idx; i < s.size() - step*words.size() + 1; i++){
            //cout<<"i ="<<i<<" "<<s.substr(i, step)<<endl;
            if(s_set.contains(s.substr(i, step))) {
                count = 0;
                checkdup.clear();
                for (int j = i; j < s.size(); j+=step) {
                    if(checkSub(s, s_set, j, step, checkdup)) {
                        count++;
                        if(count >= words.size()) {
                            //cout<<"count="<<count<<endl;                            
                            result_set.insert(i+ (count-words.size())*step);
                            checkdup[s.substr(j - step*(words.size() - 1), step)] -= 1;
                        }
                        //cout<<"count="<<count<<endl;
           
                    }else{
                        if (checkdup[s.substr(j, step)] > s_set[s.substr(j, step)])
                            i = j - count*step;
                        else
                            i = j;
                        count = 0;
                        checkdup.clear();
                        break;
                    }
                    if (j == s.size() - step )
                        i = j;                   
                }
                
            }            
            
            
        }
        }

        
        for (int res : result_set)
            result.push_back(res);
        return result;
    }
private:
    bool checkSub(string &s, unordered_map<string, int> &s_set, int begin, int step, unordered_map<string, int> &checkdup) {
        //cout<<begin<<" "<<step<<" "<<s.substr(begin, step)<<" "<<s_set.contains(s.substr(begin, step))<<endl;
        string tobechecked = s.substr(begin, step);
        if (s_set.contains(tobechecked)) {
            if(checkdup.contains(tobechecked))
                checkdup[tobechecked] += 1;
            else
                checkdup.insert({tobechecked, 1});
            
            if(checkdup[tobechecked] > s_set[tobechecked])
                return false;
            else
                return true;
        }
        return false;
    }
};
258987