<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>st;
    
    int fact(int n){
        int a=1;
        for(int i=2;i<=n;i++){
            a*=i;
        }
        return a;
    }
    
    void ans(string &t,string &s,int n){
        
        if(n==t.size()){
            if(s.size()==0)return;
            string h=s;
            sort(h.begin(),h.end());
            st.insert(h);
            return;
        }
        
        s+=t[n];
        ans(t,s,n+1);
        s.pop_back();
        ans(t,s,n+1);
    }
    
    int numTilePossibilities(string t) {
        string s="";
        ans(t,s,0);
        int as=0;
       
        for(auto c:st){
            map<char,int>m;
            int sz=c.size();
            
            for(int i=0;i<sz;i++){
                m[c[i]]++;
            }
            
            int a1=1;
            
            for(auto d:m){
                a1*= fact(d.second);
            }
            
            as+=(fact(sz)/a1);
        }
       return as;
    }
};
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