Binary Search on binary tree
Last updated: March 31, 2026
Quick Overview
Given a binary tree, implement a function to perform a binary search for a specified target value. The function should return the node containing the target if it exists, or null if the target is not found. The input will be the root of the binary tree and the target value, and the output should be the corresponding node or null.
Uber
March 31, 2026103
7
3,918 solved
Given a binary tree, implement a function to perform a binary search for a specified target value. The function should return the node containing the target if it exists, or null if the target is not found. The input will be the root of the binary tree and the target value, and the output should be the corresponding node or null.
Uber uses this problem in the Phone Screen 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
- Can you optimize the space complexity of your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to perform a binary search in a binary tree for a specified target value. The key pattern here is that while binary search is typically associated with sorted arrays, we can le...
Approach
- Start at the root node of the binary tree.
- Check if the current node is null; if it is, return null (base case).
- Compare the target value with the value of the current node:
- If they are ...
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