[LeetCode Sync] Runtime - 29 ms (71.39%), Memory - 27 MB (7.42%)

Author: NamVr

1160-letter-tile-possibilities/README.md

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+<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>

1160-letter-tile-possibilities/solution.py

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+class Solution:
+    def numTilePossibilities(self, tiles: str) -> int:
+        res = set() # all solutions
+        
+        def dfs(path, t):
+            if path not in res:
+                if path:
+                    res.add(path)
+                for i in range(len(t)):
+                    dfs(path+t[i], t[:i] + t[i+1:])
+                
+        dfs('', tiles) # start dfs with empty path (init)
+        return len(res)