1233.py

'''
1233. Remove Sub-Folders from the Filesystem
https://leetcode.com/contest/weekly-contest-159/problems/remove-sub-folders-from-the-filesystem/

Given a list of folders, 
remove all sub-folders in those folders and 
return in any order the folders after removing.
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 * 10^4
2 <= folder[i].length <= 100
folder[i] contains only lowercase letters and '/'
folder[i] always starts with character '/'
Each folder name is unique.
'''
from typing import *

class Solution:
    def removeSubfolders(self, folder: List[str]) -> List[str]:
        ans = []
        folderSet = set(folder)
        for f in folder:
            path = f
            while path:
                # Cut down last ..."/xx" to move 
                # upper level and look for it in set
                path = path[:path.rfind('/')]
                if path in folderSet:
                    break
            else:
                # Append if no break
                ans.append(f)
        return ans

print(Solution().removeSubfolders(["/a","/a/b","/c/d","/c/d/e","/c/f"]))
#['/a', '/c/d', '/c/f']
print(Solution().removeSubfolders(["/a","/a/b/c","/a/b/d"]))
#['/a']
print(Solution().removeSubfolders(["/a/b/c","/a/b/ca","/a/b/d"]))
#['/a/b/c', '/a/b/ca', '/a/b/d']