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How to Solve Find a Good Subset of the Matrix Problem
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Start Free for WindowsHard#2732
LeetCode ProblemFind a Good Subset of the Matrix
You are given a 0-indexed m x n binary matrix grid. Let us call a non-empty subset of rows good if the sum of each column of the subset is at most half of the length of the subset. More formally, if the length of the chosen subset of rows is k, then the sum of each column should be at most floor(k / 2). Return an integer array that contains row indices of a good subset sorted in ascending order. If there are multiple good subsets, you can return any of them. If there are no good subsets, return an empty array. A subset of rows of the matrix grid is any matrix that can be obtained by deleting some (possibly none or all) rows from grid.
ArrayHash TableBit ManipulationMatrix
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Problem Breakdown
Understanding the Find a Good Subset of the Matrix Problem
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Problem Statement
You are given a 0-indexed m x n binary matrix grid. Let us call a non-empty subset of rows good if the sum of each column of the subset is at most half of the length of the subset. More formally, if the length of the chosen subset of rows is k, then the sum of each column should be at most floor(k / 2). Return an integer array that contains row indices of a good subset sorted in ascending order. If there are multiple good subsets, you can return any of them. If there are no good subsets, return an empty array. A subset of rows of the matrix grid is any matrix that can be obtained by deleting some (possibly none or all) rows from grid.
HardProblem #2732
LeetCodeFind a Good Subset of the Matrix
Related Topics
ArrayHash TableBit ManipulationMatrix
How Phantom Code Helps
Get real-time assistance for Find a Good Subset of the Matrix problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
grid = [[0,1,1,0],[0,0,0,1],[1,1,1,1]]
Output
[0,1]
# Example 2
Input
grid = [[0]]
Output
[0]
# Example 3
Input
grid = [[1,1,1],[1,1,1]]
Output
[]
Constraints
m == grid.length
n == grid[i].length
1 <= m <= 104
1 <= n <= 5
grid[i][j] is either 0 or 1.
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Solve Find a Good Subset of the Matrix — You are given a 0-indexed m x n binary matrix grid. Let us call a non-empty subs...
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 Find a Good Subset of the Matrix and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Find a Good Subset of the Matrix 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 Find a Good Subset of the Matrix?
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 Find a Good Subset of the Matrix?
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 Find a Good Subset of the Matrix 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 Find a Good Subset of the Matrix 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 Find a Good Subset of the Matrix 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 Find a Good Subset of the Matrix 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 Find a Good Subset of the Matrix 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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