remove-sub-folders-from-the-filesystem

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Algorithms

Given a list of folders <code>folder</code>, return the folders after removing all sub-folders in those folders. You may return the answer in any order.

If a <code>folder[i]</code> is located within another <code>folder[j]</code>, it is called a sub-folder 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>.

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.

<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>

&nbsp;
Example 1:

<pre>
Input: folder = [&quot;/a&quot;,&quot;/a/b&quot;,&quot;/c/d&quot;,&quot;/c/d/e&quot;,&quot;/c/f&quot;]
Output: [&quot;/a&quot;,&quot;/c/d&quot;,&quot;/c/f&quot;]
Explanation: 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>

Example 2:

<pre>
Input: folder = [&quot;/a&quot;,&quot;/a/b/c&quot;,&quot;/a/b/d&quot;]
Output: [&quot;/a&quot;]
Explanation: Folders &quot;/a/b/c&quot; and &quot;/a/b/d&quot; will be removed because they are subfolders of &quot;/a&quot;.
</pre>

Example 3:

<pre>
Input: folder = [&quot;/a/b/c&quot;,&quot;/a/b/ca&quot;,&quot;/a/b/d&quot;]
Output: [&quot;/a/b/c&quot;,&quot;/a/b/ca&quot;,&quot;/a/b/d&quot;]
</pre>

&nbsp;
Constraints:

<ul>
	<li><code>1 &lt;= folder.length &lt;= 4 * 104</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 unique.</li>
</ul>