Binary Search on binary tree
Last updated: October 1, 2025
Quick Overview
Given a binary tree, implement a function to perform a binary search to determine if a specific target value exists within the tree. The function should return true if the target is found and false otherwise. You may assume that the binary tree is a binary search tree (BST), where the left subtree contains values less than the node's value and the right subtree contains values greater than the node's value.
Robinhood
October 1, 202516
15
927 solved
Given a binary tree, implement a function to perform a binary search to determine if a specific target value exists within the tree. The function should return true if the target is found and false otherwise. You may assume that the binary tree is a binary search tree (BST), where the left subtree contains values less than the node's value and the right subtree contains values greater than the node's value.
Robinhood 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 iteratively instead of recursively (or vice versa)?
- What is the worst-case input for your solution?
- What if the input doesn't fit in memory?
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Problem Analysis
The problem requires us to search for a target value in a binary search tree (BST). A BST has a specific property where for any given node, all values in the left subtree are less than the node's valu...
Approach
- Start at the root of the binary tree.
- Compare the target value with the current node's value:
- If they are equal, return true (target found).
- If the target is less than the current node...
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