<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>

from copy import copy

class Solution:
    def numTilePossibilities(self, tiles: str) -> int:
        res = 0
        str_arr = []        

        for i in tiles:
            str_arr.append(i)
        
        def helper_function(str_arr):
            if len(str_arr) == 0:
                return [[]]
            
            new_list = []
            
            char = str_arr[0]

            word_2d_list = helper_function(str_arr[1:])

            for i in word_2d_list:
                for j in range(len(i)+1):
                    copy_wl = copy(i)
                    copy_wl.insert(j, char)
                    if copy_wl in new_list:
                        continue
                    else:
                        new_list.append(copy_wl)
            
            new_list.extend(word_2d_list)
            
            return new_list
                    
        list_2d = helper_function(str_arr)
        
        str_a = []
        for i in list_2d:
            temp = ''.join(i)
            if temp in str_a:
                continue
            else:
                str_a.append(temp)
        
        return(len(str_a)-1)
19500