Find a Local Minimum with Left-Biased Binary Search
Last updated: August 8, 2026
Quick Overview
The question asks the candidate to implement a solution to find a local minimum in an array using a left-biased binary search approach.
Meta
August 8, 20263
0
24 solved
The question asks the candidate to implement a solution to find a local minimum in an array using a left-biased binary search approach.
This question is typically asked during the onsite interview round for software engineering roles at Meta to assess a candidate's problem-solving skills and understanding of binary search algorithms. The interviewer is evaluating the candidate's ability to think algorithmically, optimize their solution, and handle edge cases effectively. Demonstrating a clear thought process and coding proficiency is crucial in this round.
What the Interviewer Expects
- Explain the concept of a local minimum clearly.
- Outline the left-biased binary search approach step-by-step.
- Provide a working implementation in Python.
- Discuss the time and space complexity of the solution.
- Handle edge cases and explain how they are managed in the code.
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 explain why a left-biased approach is used?
- What would happen if the array is not strictly increasing or decreasing?
- How would you modify your solution to find all local minima?
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Practice DSA ProblemsSample Answer
Framing
To find a local minimum in an array, we need to identify an element that is smaller than its neighbors. A local minimum may not necessarily be the global minimum, and we can use a binary search techni...
Approach
We will implement a left-biased binary search. The idea is to check the middle element of the array and compare it with its neighbors. If the middle element is less than both neighbors, we have found ...
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