Count median in linked list
Last updated: September 25, 2025
Quick Overview
Given a singly linked list of integers, write a function to calculate and return the median value of the elements in the list. If the number of elements is odd, return the middle element; if even, return the average of the two middle elements. The function should handle edge cases, such as an empty list, appropriately.
Meta
September 25, 2025526
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Given a singly linked list of integers, write a function to calculate and return the median value of the elements in the list. If the number of elements is odd, return the middle element; if even, return the average of the two middle elements. The function should handle edge cases, such as an empty list, appropriately.
Meta 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
- Can you solve this in a single pass?
- What happens if the input contains duplicates?
- How would you parallelize this solution?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To calculate the median of a singly linked list, we need to identify the number of elements in the list first. The median is defined as the middle value in an ordered list, which means we either need ...
Approach
- Traverse the Linked List: Use a single pass to count the total number of elements in the list while simultaneously storing the values in an array (or a list). This allows us to easily access el...
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