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How to Solve Matrix Diagonal Sum Problem

Master the Matrix Diagonal Sum LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.

Phantom Code 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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Easy#1572

LeetCode Problem

Matrix Diagonal Sum

Given a square matrix mat, return the sum of the matrix diagonals. Only include the sum of all the elements on the primary diagonal and all the elements on the secondary diagonal that are not part of the primary diagonal.

ArrayMatrix

Phantom Code will help you solve this problem in real-time during your interview

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Problem Breakdown

Understanding the Matrix Diagonal Sum Problem

Let's break down this LeetCode problem and understand what makes it challenging in interview settings.

Problem Statement

EasyProblem #1572

LeetCode

Matrix Diagonal Sum

How Phantom Code Helps

Get real-time assistance for Matrix Diagonal Sum problems during coding interviews. Phantom Code provides instant solutions and explanations.

Examples

# Example 1

Input

mat = [[1,2,3], [4,5,6], [7,8,9]]

Output

# Example 2

Input

mat = [[1,1,1,1], [1,1,1,1], [1,1,1,1], [1,1,1,1]]

Output

# Example 3

Input

mat = [[5]]

Output

Constraints

n == mat.length == mat[i].length

1 <= n <= 100

1 <= mat[i][j] <= 100

How Phantom Code Helps with LeetCode Problems

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Watch how Phantom Code helps solve LeetCode problems during live interviews

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Solve Matrix Diagonal Sum — Given a square matrix mat, return the sum of the matrix diagonals. Only include ...

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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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

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CodeSignal

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CoderPad

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Teams

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User results and traction

Thousands of developers use Phantom Code. Social proof signals that this approach helps real candidates land offers across a range of companies.

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 Matrix Diagonal Sum and using Phantom Code during coding interviews.

How does Phantom Code help me solve coding problems like Matrix Diagonal Sum 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 Matrix Diagonal Sum?

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 Matrix Diagonal Sum?

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 Matrix Diagonal Sum 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 Matrix Diagonal Sum 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 Matrix Diagonal Sum 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 Matrix Diagonal Sum 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 Matrix Diagonal Sum 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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