<p>You have <code>n</code>&nbsp;&nbsp;<code>tiles</code>, where each tile has one letter <code>tiles[i]</code> printed on it.</p>

<p>Return <em>the number of possible non-empty sequences of letters</em> you can make using the letters printed on those <code>tiles</code>.</p>

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

<pre>
<strong>Input:</strong> tiles = &quot;AAB&quot;
<strong>Output:</strong> 8
<strong>Explanation: </strong>The possible sequences are &quot;A&quot;, &quot;B&quot;, &quot;AA&quot;, &quot;AB&quot;, &quot;BA&quot;, &quot;AAB&quot;, &quot;ABA&quot;, &quot;BAA&quot;.
</pre>

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

<pre>
<strong>Input:</strong> tiles = &quot;AAABBC&quot;
<strong>Output:</strong> 188
</pre>

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

<pre>
<strong>Input:</strong> tiles = &quot;V&quot;
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>1 &lt;= tiles.length &lt;= 7</code></li>
	<li><code>tiles</code> consists of uppercase English letters.</li>
</ul>

class Solution {
public:
    set<string>res; 
    void solve(vector<char>val,map<char,int>&store,string &temp) {
     
       if(temp.size() > 0 ) {
           res.insert(temp);
       }
       
        
       for(int i=0;i<val.size();i++){ 
           
           if(store[val[i]] != 0){
               temp = temp + val[i]; 
               store[val[i]]--; 
               solve(val,store,temp); 
               temp.pop_back();  
               store[val[i]]++;  
           }    
       }  
    } 
    int numTilePossibilities(string tiles) {
          
        map<char,int>store; 
        res.clear(); 
        
        for(int i=0;i<tiles.size(); i++) {
            store[tiles[i]]++;
        } 
        
        vector<char>val;
        
        for(auto x: store) {
            val.push_back(x.first);
        }
        string temp =""; 
        
        solve(val,store,temp); 
        
        return res.size();
    }
};
22551