Binary Search on linked list
Last updated: November 1, 2025
Quick Overview
Implement a binary search algorithm on a sorted linked list to determine if a target value exists within the list. The function should return a boolean indicating whether the target is found. The linked list will be provided as input, along with the target value to search for.
Datadog
November 1, 20253
13
4,261 solved
Implement a binary search algorithm on a sorted linked list to determine if a target value exists within the list. The function should return a boolean indicating whether the target is found. The linked list will be provided as input, along with the target value to search for.
This coding problem is frequently asked during Onsite at Datadog. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Datadog expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
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 test this solution thoroughly?
- How would your solution change if the input was sorted?
- What if the input doesn't fit in memory?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
In this problem, we need to perform a binary search on a sorted linked list. Normally, binary search is implemented on an array where random access is possible, allowing us to quickly find the mid-poi...
Approach
- Initialize two pointers,
startandend, to the head of the linked list andNone, respectively. - Use a loop to traverse the linked list until the
startpointer is not equal to theend...
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