Find median in linked list
Last updated: June 6, 2026
Quick Overview
Given a singly linked list, write a function to find the median value of the elements in the list. The median is defined as the middle element when the list is sorted; if the list has an even number of elements, return the average of the two middle elements. Your function should handle cases where the linked list is empty.
SentinelOne
June 6, 202628
10
4,942 solved
Given a singly linked list, write a function to find the median value of the elements in the list. The median is defined as the middle element when the list is sorted; if the list has an even number of elements, return the average of the two middle elements. Your function should handle cases where the linked list is empty.
SentinelOne 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
- 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
- What is the worst-case input for your solution?
- How would you test this solution thoroughly?
- What happens if the input contains duplicates?
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Practice DSA ProblemsSample Answer
Problem Analysis
To find the median in a singly linked list, we need to consider the properties of median selection. The median is the middle value in a sorted list; if the list has an even number of elements, it's th...
Approach
- Count the elements: Traverse the linked list to count the total number of nodes.
- Identify the median position: If the total count is odd, the median is the node at index
count // 2. I...
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