Validate matrix complete
Last updated: November 3, 2025
Quick Overview
Given a matrix, write a function to determine if it is a complete matrix, meaning all rows are of the same length and all elements are filled without any gaps. The function should take a 2D array as input and return a boolean indicating whether the matrix is complete.
Jane Street
November 3, 202536
8
2,323 solved
Given a matrix, write a function to determine if it is a complete matrix, meaning all rows are of the same length and all elements are filled without any gaps. The function should take a 2D array as input and return a boolean indicating whether the matrix is complete.
Coding interviews at Jane Street focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would your solution change if the input was sorted?
- How would you test this solution thoroughly?
- What happens if the input contains duplicates?
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Problem Analysis
To determine if a matrix is complete, we need to ensure two conditions are met: all rows must have the same length, and all elements in the matrix should be filled without any gaps (i.e., no None or e...
Approach
- Initialize a reference length: Start by checking the length of the first row, which will serve as our reference length.
- Iterate through each row: For each subsequent row, check if its l...
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