Optimize partitioning for in-place
Last updated: June 14, 2026
Quick Overview
Given an array of integers, implement an in-place partitioning algorithm that rearranges the elements 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. The function should modify the array directly and return the index of the pivot after partitioning.
CrowdStrike
June 14, 202629
4
1,974 solved
Given an array of integers, implement an in-place partitioning algorithm that rearranges the elements 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. The function should modify the array directly and return the index of the pivot after partitioning.
Coding interviews at CrowdStrike 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 iteratively instead of recursively (or vice versa)?
- How would you modify your solution to handle streaming input?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to partition an array based on a pivot value, such that all elements less than the pivot are on one side and all elements greater than or equal to the pivot are on the other. T...
Approach
- Initialize two pointers:
leftstarting at the beginning of the array (index 0) andrightstarting at the end of the array (last index). - Loop while
leftis less thanright:- If th...
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