Transform linked list to tree
Last updated: August 14, 2025
Quick Overview
Given a singly linked list, transform it into a balanced binary search tree (BST). The resulting tree should maintain the order of elements from the linked list, and you should return the root node of the constructed BST. The input will be the head of the linked list, and the output will be the root of the tree.
Confluent
August 14, 20255
8
3,902 solved
Given a singly linked list, transform it into a balanced binary search tree (BST). The resulting tree should maintain the order of elements from the linked list, and you should return the root node of the constructed BST. The input will be the head of the linked list, and the output will be the root of the tree.
This coding problem is frequently asked during Technical Screen at Confluent. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Confluent 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 parallelize this solution?
- What is the worst-case input for your solution?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To transform a singly linked list into a balanced binary search tree (BST), we recognize that this problem exhibits a divide-and-conquer pattern. In a balanced BST, the left and right subtrees of any ...
Approach
- Count the Nodes: First, we need to determine the number of nodes in the linked list to facilitate finding the middle. This will help in identifying the root of the BST.
- **Recursive Construc...
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