Validate linked list valid BST
Last updated: September 22, 2025
Quick Overview
Determine if a given interval list satisfies the balanced property.
Capital One
September 22, 20255
12
213 solved
Determine if a given interval list satisfies the balanced property.
This coding problem is frequently asked during Phone Screen at Capital One. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Capital One 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
- What is the worst-case input for your solution?
- What happens if the input contains duplicates?
- What if the input doesn't fit in memory?
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Problem Analysis
To determine if a given binary tree is a valid Binary Search Tree (BST), we can utilize a recursive approach. The key property of a BST is that for any node, all values in its left subtree must be les...
Approach
- Define a recursive helper function that takes a node and two bounds (low and high) as parameters.
- If the current node is null, return true (an empty subtree is a valid BST).
- Check if the no...
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