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1233. Remove Sub-Folders from the Filesystem

Difficulty Topics

Description

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:

  • 1 <= folder.length <= 4 * 104
  • 2 <= folder[i].length <= 100
  • folder[i] contains only lowercase letters and '/'.
  • folder[i] always starts with the character '/'.
  • Each folder name is unique.

Solution

remove-sub-folders-from-the-filesystem.py
class Solution:
    def removeSubfolders(self, folder: List[str]) -> List[str]:
        folder.sort(key = len)
        s = set()
        res = []

        for f in folder:
            path = f.split("/")[1:]
            full = ""
            for p in path:
                full += p
                if full in s: break
            else:
                s.add(full)
                res.append(f)



        return res