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How to Solve Remove Sub-Folders from the Filesystem Problem
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Start Free for WindowsMedium#1233
LeetCode ProblemRemove Sub-Folders from the Filesystem
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. A sub-folder of folder[j] must start with folder[j], followed by a "/". For example, "/a/b" is a sub-folder of "/a", but "/b" is not a sub-folder of "/a/b/c". The format of a path is one or more concatenated strings of the form: '/' followed by one or more lowercase English letters.
ArrayStringDepth-First SearchTrie
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Problem Breakdown
Understanding the Remove Sub-Folders from the Filesystem Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
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. A sub-folder of folder[j] must start with folder[j], followed by a "/". For example, "/a/b" is a sub-folder of "/a", but "/b" is not a sub-folder of "/a/b/c". The format of a path is one or more concatenated strings of the form: '/' followed by one or more lowercase English letters.
MediumProblem #1233
LeetCodeRemove Sub-Folders from the Filesystem
Related Topics
ArrayStringDepth-First SearchTrie
How Phantom Code Helps
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Examples
# Example 1
Input
folder = ["/a","/a/b","/c/d","/c/d/e","/c/f"]
Output
["/a","/c/d","/c/f"]
# Example 2
Input
folder = ["/a","/a/b/c","/a/b/d"]
Output
["/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.
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Solve Remove Sub-Folders from the Filesystem — Given a list of folders folder, return the folders after removing all sub-folder...
Here's the optimal approach using Array:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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Frequently Asked Questions
Common questions about solving Remove Sub-Folders from the Filesystem and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Remove Sub-Folders from the Filesystem during interviews?
Phantom Code generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Remove Sub-Folders from the Filesystem?
Phantom Code adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code help me communicate my solution for problems like Remove Sub-Folders from the Filesystem?
Yes. Phantom Code provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code assist with different programming languages for Remove Sub-Folders from the Filesystem type problems?
Phantom Code supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code help me avoid during Remove Sub-Folders from the Filesystem interviews?
Phantom Code catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code detectable when solving problems like Remove Sub-Folders from the Filesystem during live interviews?
No. Phantom Code runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code help when I'm struggling with Remove Sub-Folders from the Filesystem style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code work for the coding platforms used in Remove Sub-Folders from the Filesystem interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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