<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:
    string curr;
    set<string> all;

    // void uniquepermut(string curr)
    // {
    //     // generate every permutation of string curr
    //     do
    //     {
    //         all.insert(curr);

    //     } while (next_permutation(curr.begin(), curr.end()));
    // }
    void permute(string& a, int l, int r) 
{ 
    // Base case 
    string curr1 = a;
    sort(curr1.begin(), curr1.end());
    do{
        all.insert(curr1);
    }while(next_permutation(curr1.begin(), curr1.end()));
    // if (l == r) 
    //     all.insert(a);
    // else { 
    //     // Permutations made 
    //     for (int i = l; i <= r; i++) { 
  
    //         // Swapping done 
    //         swap(a[l], a[i]); 
  
    //         // Recursion called 
    //         permute(a, l + 1, r); 
  
    //         // backtrack 
    //         swap(a[l], a[i]); 
    //     } 
    // } 
} 
    void rec(int level, string tiles)
    {
        if (level == tiles.length())
        {
            cout<<curr<<"\n";
            permute(curr,0, curr.length()-1);
            return;
        }
        rec(level + 1, tiles);
        curr.push_back(tiles[level]);
        rec(level + 1, tiles);
        curr.pop_back();
    }
    int numTilePossibilities(string tiles)
    {
        rec(0, tiles);
        for(auto i: all){
            cout<<i<<" ";
        }
        return all.size()-1;
    }
};
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