[LeetCode Sync] Runtime - 3 ms (89.59%), Memory - 18.7 MB (69.06%)

Author: NinePiece2

Solutions/0800-letter-case-permutation/README.md

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+<p>Given a string <code>s</code>, you&nbsp;can transform every letter individually to be lowercase or uppercase to create another string.</p>
+
+<p>Return <em>a list of all possible strings we could create</em>. Return the output in <strong>any order</strong>.</p>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;a1b2&quot;
+<strong>Output:</strong> [&quot;a1b2&quot;,&quot;a1B2&quot;,&quot;A1b2&quot;,&quot;A1B2&quot;]
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> s = &quot;3z4&quot;
+<strong>Output:</strong> [&quot;3z4&quot;,&quot;3Z4&quot;]
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= s.length &lt;= 12</code></li>
+	<li><code>s</code> consists of lowercase English letters, uppercase English letters, and digits.</li>
+</ul>

Solutions/0800-letter-case-permutation/solution.py

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+class Solution:
+    def letterCasePermutation(self, s: str) -> List[str]:
+        # result = []
+        # n = sum(char.isalpha() for char in s)
+
+        # for i in range(1 << n):
+        #     j, tmp = 0, []
+        #     for char in s:
+        #         if char.isalpha():
+        #             char = char.lower() if (i >> j) & 1 else char.upper()
+        #             j += 1
+        #         tmp.append(char)
+        #     result.append("".join(tmp))
+
+        # return result
+
+        result = [""]
+        for char in s:
+            if char.isdigit():
+                result = [rchar + char for rchar in result]
+            else:
+                result = [rchar + val for rchar in result for val in (char.upper(), char.lower())]
+        
+        return result