Sliding Window on matrix
Last updated: April 29, 2026
Quick Overview
Given a 2D matrix of integers, implement a sliding window technique to find the maximum sum of any submatrix of a specified size. The input will consist of the matrix dimensions and the size of the sliding window, and the output should be the maximum sum found within any valid submatrix.
Spotify
April 29, 202638
16
2,958 solved
Given a 2D matrix of integers, implement a sliding window technique to find the maximum sum of any submatrix of a specified size. The input will consist of the matrix dimensions and the size of the sliding window, and the output should be the maximum sum found within any valid submatrix.
Spotify uses this problem in the Technical Screen 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
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of finding the maximum sum of any submatrix with a specified size in a 2D matrix, we can utilize the sliding window technique. This technique is particularly applicable here b...
Approach
- Input Parameters: We have a matrix of size
m x nand a sliding window size defined byk x l, wherekis the number of rows andlis the number of columns in the submatrix. - **Initial ...
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