1233 - Remove Sub-Folders from the Filesystem\.

Medium

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

If a folder[i] is located within another folder[j], it is called a sub-folder of it.

The format of a path is one or more concatenated strings of the form: '/' followed by one or more lowercase English letters.

• For example, "/leetcode" and "/leetcode/problems" are valid paths while an empty string and "/" are not.

Example 1:

Input: folder = "/a","/a/b","/c/d","/c/d/e","/c/f"

Output: "/a","/c/d","/c/f"

Explanation: Folders "/a/b" is a subfolder of "/a" and "/c/d/e" is inside of folder "/c/d" in our filesystem.

Example 2:

Input: folder = "/a","/a/b/c","/a/b/d"

Output: "/a"

Explanation: Folders "/a/b/c" and "/a/b/d" will be removed because they are subfolders of "/a".

Example 3:

Input: folder = "/a/b/c","/a/b/ca","/a/b/d"

Output: "/a/b/c","/a/b/ca","/a/b/d"

Constraints:

• <code>1 <= folder.length <= 4 * 10⁴</code>

• 2 <= folder[i].length <= 100

• folder[i] contains only lowercase letters and '/'.

• folder[i] always starts with the character '/'.

• Each folder name is unique.