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How to Solve Compact Object Problem
Master the Compact Object LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
PhantomCodeAI generates complete solutions and debugging hints that you can use while explaining your approach, so you stay calm and in control.
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Medium#2705
LeetCode ProblemCompact Object
Given an object or array obj, return a compact object. A compact object is the same as the original object, except with keys containing falsy values removed. This operation applies to the object and any nested objects. Arrays are considered objects where the indices are keys. A value is considered falsy when Boolean(value) returns false. You may assume the obj is the output of JSON.parse. In other words, it is valid JSON.
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Problem Breakdown
Understanding the Compact Object Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
Given an object or array obj, return a compact object. A compact object is the same as the original object, except with keys containing falsy values removed. This operation applies to the object and any nested objects. Arrays are considered objects where the indices are keys. A value is considered falsy when Boolean(value) returns false. You may assume the obj is the output of JSON.parse. In other words, it is valid JSON.
MediumProblem #2705
LeetCodeCompact Object
Related Topics
How PhantomCodeAI Helps
Get real-time assistance for Compact Object problems during coding interviews. PhantomCodeAI provides instant solutions and explanations.
Examples
# Example 1
Input
obj = [null, 0, false, 1]
Output
[1]
# Example 2
Input
obj = {"a": null, "b": [false, 1]}Output
{"b": [1]}# Example 3
Input
obj = [null, 0, 5, [0], [false, 16]]
Output
[5, [], [16]]
Constraints
obj is a valid JSON object
2 <= JSON.stringify(obj).length <= 106
How PhantomCodeAI Helps with LeetCode Problems
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Solve Compact Object — Given an object or array obj, return a compact object. A compact object is the s...
Here's the optimal approach using the right algorithm:
def solve(input):
# Optimal O(n) solution
return result
Time: O(n) | Space: O(n)
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Undetectability Checklist
Run compatibility test before interviews
Use recommended Zoom version settings
Enable advanced screen capture options
Verify native desktop architecture
Test with screen recording software
Platform Compatibility
Zoom
Supported
Google Meet
Supported
HackerRank
Supported
CodeSignal
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CoderPad
Supported
Teams
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User results and traction
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Undetectability and technical details
Our native desktop architecture avoids common detection vectors used by browser extensions. We provide a clear checklist so you can run basic checks and confirm the app will be invisible.
Platform compatibility and limitations
We work with Zoom, HackerRank, CodeSignal, CoderPad and other web-based platforms. Check the compatibility note and request a browser link if a specific desktop app is unsupported.
Frequently Asked Questions
Common questions about solving Compact Object and using PhantomCodeAI during coding interviews.
How does PhantomCodeAI help with LeetCode problems during a coding interview?
PhantomCodeAI reads the problem from a screenshot or listens to it via audio, then generates a complete solution with a step-by-step approach and time/space complexity, so you can focus on explaining your reasoning rather than getting stuck on implementation.
Which programming languages does PhantomCodeAI support?
11 languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set a preferred language to get idiomatic solutions.
Does PhantomCodeAI work with HackerRank, CodeSignal, and CoderPad?
Yes — it works alongside LeetCode, HackerRank, CodeSignal, CoderPad, and HackerEarth, plus any browser-based coding environment.
Can PhantomCodeAI handle follow-up questions and modifications?
Yes. Capture the modified problem by screenshot or audio and get an updated solution within seconds, including new edge cases and optimizations.
Is PhantomCodeAI detectable during live interviews?
PhantomCodeAI runs as a native desktop overlay that does not appear in screen shares, recordings, or proctoring software, and works with Zoom, Google Meet, Microsoft Teams, and major coding platforms.
Should I still practice these problems on my own first?
Yes. The most durable preparation is solving problems unaided first, then using AI afterward to review your approach, complexity, and missed edge cases — use it to debrief and learn, not to skip the reps.
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