Implement a Sliding Window Maximum
Last updated: February 21, 2025
Quick Overview
Given an array of integers and a window size k, return the maximum value in each sliding window position as the window moves from left to right.
Rivian
February 21, 202515
8
2,365 solved
Given an array of integers and a window size k, return the maximum value in each sliding window position as the window moves from left to right.
This problem tests your knowledge of monotonic deques, a technique relevant to signal processing in vehicle systems. At Rivian, similar patterns are used for processing windowed sensor data, detecting peak values in telemetry streams, and analyzing battery discharge curves.
What the Interviewer Expects
- Implement using a monotonic deque for O(n) total time complexity
- Maintain the deque invariant correctly: decreasing order from front to back
- Handle window boundaries using index-based expiration
- Handle edge cases including k=1 and k equal to array length
- Explain why the brute force O(nk) approach is insufficient
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 if you needed both the max and min in each window?
- How would you adapt this for a data stream where elements arrive one at a time?
- Can you solve this with a different approach like a balanced BST?
- How would you parallelize this for very large arrays?
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Problem Analysis
This problem is best solved using a monotonic deque, which is a specialized double-ended queue that maintains its elements in a specific order. Here, we want the deque to hold indices of the array ele...
Approach
- Initialize an empty deque and an output list to store the maximums.
- Iterate through the array using an index
i.- For each element, remove indices from the front of the deque if they are ou...
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