Validate matrix sorted
Last updated: March 6, 2026
Quick Overview
Given a matrix of integers where each row and each column is sorted in non-decreasing order, write a function to determine if the matrix is sorted. The function should return true if the matrix is sorted and false otherwise. The input will be a 2D array of integers, and the output will be a boolean value.
HubSpot
March 6, 2026163
12
3,383 solved
Given a matrix of integers where each row and each column is sorted in non-decreasing order, write a function to determine if the matrix is sorted. The function should return true if the matrix is sorted and false otherwise. The input will be a 2D array of integers, and the output will be a boolean value.
Coding interviews at HubSpot 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
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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
- Can you solve this in a single pass?
- What happens if the input contains duplicates?
- What if the input doesn't fit in memory?
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Problem Analysis
To determine if a matrix is sorted, we can leverage the properties of the matrix where each row and each column is sorted in non-decreasing order. This suggests a systematic approach using a single it...
Approach
- Start with the first row of the matrix and check if all elements are in non-decreasing order. For example, given the row [1, 2, 2], we can check that: 1 <= 2 and 2 <= 2 are both true.
- Next, iter...
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