Optimize partitioning for O(1) space
Last updated: August 15, 2025
Quick Overview
Given an array of integers, optimize the partitioning of the array such that all elements less than a specified pivot are on one side and all elements greater than or equal to the pivot are on the other side, while using O(1) additional space. The function should modify the array in place and return the index of the pivot after partitioning.
Grafana Labs
August 15, 20254
6
4,776 solved
Given an array of integers, optimize the partitioning of the array such that all elements less than a specified pivot are on one side and all elements greater than or equal to the pivot are on the other side, while using O(1) additional space. The function should modify the array in place and return the index of the pivot after partitioning.
Grafana Labs 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
- How would you modify your solution to handle streaming input?
- What is the worst-case input for your solution?
- Can you optimize the space complexity of your solution?
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Problem Analysis
This problem is best approached using the two pointers technique. The challenge requires partitioning the array in such a way that all elements less than the pivot are on one side, and all element...
Approach
- Initialize Pointers: Start with two pointers,
iat the beginning of the array andjalso at the beginning. - Iterate through the Array: Move
jthrough the array.- For each elem...
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