remove-sub-folders-from-the-filesystem.md

<p>Given a list of folders, remove all sub-folders in those folders and return in <strong>any order</strong> the folders after removing.</p>

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

<p>The format of a path is&nbsp;one or more concatenated strings of the form:&nbsp;<code>/</code>&nbsp;followed by one or more lowercase English letters. For example,&nbsp;<code>/leetcode</code>&nbsp;and&nbsp;<code>/leetcode/problems</code>&nbsp;are valid paths while an empty string and&nbsp;<code>/</code>&nbsp;are not.</p>

<p>&nbsp;</p>
<p><strong>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>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>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&nbsp;&lt;= 4 * 10^4</code></li>
	<li><code>2 &lt;= folder[i].length &lt;= 100</code></li>
	<li><code>folder[i]</code> contains only&nbsp;lowercase letters and &#39;/&#39;</li>
	<li><code>folder[i]</code> always starts with character &#39;/&#39;</li>
	<li>Each folder name is unique.</li>
</ul>