Validate graph symmetric
Last updated: November 15, 2025
Quick Overview
Determine if a given graph satisfies the valid BST property.
Square/Block
Coding & Algorithms
Software Engineer
Square/Block
November 15, 2025Software Engineer
Technical Screen
Coding & Algorithms
Easy
37
6
4,264 solved
Determine if a given graph satisfies the valid BST property.
Coding interviews at Square/Block 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
- 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
Dynamic programming and memoization
Edge cases and input validation
Binary search and divide and conquer
Tree structures and recursion
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 happens if the input contains duplicates?
- How would you modify your solution to handle streaming input?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if a given graph satisfies the valid Binary Search Tree (BST) property, we need to check if for every node, all values in its left subtree are less than the node's value, and all values i...
Approach
- Define a Recursive Function: Create a helper function,
is_valid_bst(node, low, high), which takes a node and its valid range (low and high). - Base Case: If the node is
None, return `...
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