Validate matrix valid BST
Last updated: November 27, 2025
Quick Overview
Given a binary tree represented as a matrix, write a function to determine if it is a valid binary search tree (BST). A valid BST must satisfy the property that for any given node, all values in its left subtree are less than the node's value, and all values in its right subtree are greater. The function should return a boolean indicating whether the matrix representation corresponds to a valid BST.
Confluent
November 27, 202544
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2,278 solved
Given a binary tree represented as a matrix, write a function to determine if it is a valid binary search tree (BST). A valid BST must satisfy the property that for any given node, all values in its left subtree are less than the node's value, and all values in its right subtree are greater. The function should return a boolean indicating whether the matrix representation corresponds to a valid BST.
Coding interviews at Confluent focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
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 your solution change if the input was sorted?
- Can you solve this in a single pass?
- How would you test this solution thoroughly?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if the given binary tree matrix represents a valid Binary Search Tree (BST), we need to validate the BST properties for each node. The specific pattern we will recognize here is a **Depth...
Approach
- Input Representation: The binary tree is represented as a matrix where the root is at (0, 0), and children of node at (i, j) are at (2i + 1, j + 1) for the left child and (2i + 2, j + 1) for th...
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