Validate binary tree complete
Last updated: January 22, 2026
Quick Overview
Determine if a given binary tree satisfies the balanced property.
Figma
Coding & Algorithms
Software Engineer
Figma
January 22, 2026Software Engineer
Onsite
Coding & Algorithms
Medium
170
14
1,012 solved
Determine if a given binary tree satisfies the balanced property.
Figma uses this problem in the Onsite 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
Time and space complexity analysis
Graph algorithms and traversal
Edge cases and input validation
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
- How would you modify your solution to handle streaming input?
- What if the input doesn't fit in memory?
- How would you parallelize this solution?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
To determine if a binary tree is complete, we need to check that all levels of the tree are fully filled except possibly for the last level, which must be filled from left to right. The most suitable ...
Approach
- Initialize a queue to perform BFS, starting with the root node.
- Use a boolean flag,
end, to indicate when we encounter a null node, which means any subsequent nodes must also be null to satis...
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