# 1233. Remove Sub-Folders from the Filesystem

yPhantom 2019年10月20日 118次浏览

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.

## Solution

Java版

``````class Solution {
public List<String> removeSubfolders(String[] folder) {
List<String> ant = new ArrayList<>();
Arrays.sort(folder);
String parent = "/";
for (String f: folder) {
int pSize = parent.length();
if (f.length() <= pSize || f.charAt(pSize) != '/' || !f.startsWith(parent)) {
parent = f;
}
}
return ant;
}
}
``````

Python版

``````def removeSubfolders(self, folder: List[str]) -> List[str]:
folder.sort()
ans, parent = [], '/'
for f in folder:
pSize = len(parent)
if len(f) <= pSize or f[pSize] != '/' or f[: pSize] != parent:
parent = f
ans.append(f)
return ans
``````