Sync LeetCode submission Runtime - 18 ms (95.62%), Memory - 30.5 MB (77.26%)

Author: jimit105

1350-remove-sub-folders-from-the-filesystem/README.md

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+<p>Given a list of folders <code>folder</code>, return <em>the folders after removing all <strong>sub-folders</strong> in those folders</em>. You may return the answer in <strong>any order</strong>.</p>
+
+<p>If a <code>folder[i]</code> is located within another <code>folder[j]</code>, it is called a <strong>sub-folder</strong> of it. A sub-folder of <code>folder[j]</code> must start with <code>folder[j]</code>, followed by a <code>&quot;/&quot;</code>. For example, <code>&quot;/a/b&quot;</code> is a sub-folder of <code>&quot;/a&quot;</code>, but <code>&quot;/b&quot;</code> is not a sub-folder of <code>&quot;/a/b/c&quot;</code>.</p>
+
+<p>The format of a path is one or more concatenated strings of the form: <code>&#39;/&#39;</code> followed by one or more lowercase English letters.</p>
+
+<ul>
+	<li>For example, <code>&quot;/leetcode&quot;</code> and <code>&quot;/leetcode/problems&quot;</code> are valid paths while an empty string and <code>&quot;/&quot;</code> are not.</li>
+</ul>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+
+<pre>
+<strong>Input:</strong> folder = [&quot;/a&quot;,&quot;/a/b&quot;,&quot;/c/d&quot;,&quot;/c/d/e&quot;,&quot;/c/f&quot;]
+<strong>Output:</strong> [&quot;/a&quot;,&quot;/c/d&quot;,&quot;/c/f&quot;]
+<strong>Explanation:</strong> Folders &quot;/a/b&quot; is a subfolder of &quot;/a&quot; and &quot;/c/d/e&quot; is inside of folder &quot;/c/d&quot; in our filesystem.
+</pre>
+
+<p><strong class="example">Example 2:</strong></p>
+
+<pre>
+<strong>Input:</strong> folder = [&quot;/a&quot;,&quot;/a/b/c&quot;,&quot;/a/b/d&quot;]
+<strong>Output:</strong> [&quot;/a&quot;]
+<strong>Explanation:</strong> Folders &quot;/a/b/c&quot; and &quot;/a/b/d&quot; will be removed because they are subfolders of &quot;/a&quot;.
+</pre>
+
+<p><strong class="example">Example 3:</strong></p>
+
+<pre>
+<strong>Input:</strong> folder = [&quot;/a/b/c&quot;,&quot;/a/b/ca&quot;,&quot;/a/b/d&quot;]
+<strong>Output:</strong> [&quot;/a/b/c&quot;,&quot;/a/b/ca&quot;,&quot;/a/b/d&quot;]
+</pre>
+
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>1 &lt;= folder.length &lt;= 4 * 10<sup>4</sup></code></li>
+	<li><code>2 &lt;= folder[i].length &lt;= 100</code></li>
+	<li><code>folder[i]</code> contains only lowercase letters and <code>&#39;/&#39;</code>.</li>
+	<li><code>folder[i]</code> always starts with the character <code>&#39;/&#39;</code>.</li>
+	<li>Each folder name is <strong>unique</strong>.</li>
+</ul>

1350-remove-sub-folders-from-the-filesystem/solution.py

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+# Approach 2: Using Sorting
+
+# N = len(folder), L = max length of folder path
+# Time: O(N * L log N)
+# Space: O(N * L)
+
+class Solution:
+    def removeSubfolders(self, folder: List[str]) -> List[str]:
+        folder.sort()
+
+        result = [folder[0]]
+
+        for i in range(1, len(folder)):
+            last_folder = result[-1]
+            last_folder += '/'
+
+            if not folder[i].startswith(last_folder):
+                result.append(folder[i])
+
+        return result