Binary Search on matrix
Last updated: June 11, 2026
Quick Overview
Given a 2D matrix of integers where each row is sorted in ascending order and each column is also sorted in ascending order, implement a function to perform a binary search to determine if a target value exists in the matrix. The function should return true if the target is found and false otherwise. The input will be the matrix and the target value, and the output will be a boolean.
Supabase
June 11, 202638
12
1,448 solved
Given a 2D matrix of integers where each row is sorted in ascending order and each column is also sorted in ascending order, implement a function to perform a binary search to determine if a target value exists in the matrix. The function should return true if the target is found and false otherwise. The input will be the matrix and the target value, and the output will be a boolean.
Supabase uses this problem in the Take-home Project to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
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
- What happens if the input contains duplicates?
- How would you parallelize this solution?
- What if the input doesn't fit in memory?
- What is the worst-case input for your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
In this problem, we are given a 2D matrix where each row and each column is sorted in ascending order. This implies that if we take any element, all elements to the right are greater, and all elements...
Approach
- Start by defining the dimensions of the matrix,
rowsandcols. - Utilize a binary search approach where we calculate the middle index in the conceptual 1D array formed from the 2D matrix. The ...
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