traversal on Binary Tree
Last updated: April 15, 2026
Quick Overview
Given a binary tree, implement a function to perform an in-order traversal and return the values of the nodes in an array. The function should take the root of the binary tree as input and output an array of integers representing the node values in the order they were visited.
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April 15, 202661
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Given a binary tree, implement a function to perform an in-order traversal and return the values of the nodes in an array. The function should take the root of the binary tree as input and output an array of integers representing the node values in the order they were visited.
This coding problem is frequently asked during Phone Screen at Figma. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Figma expects candidates to write production-quality code, not just solve the puzzle.
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
- What if the input doesn't fit in memory?
- How would your solution change if the input was sorted?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of performing an in-order traversal of a binary tree, we can recognize that this traversal follows a specific pattern: visit the left subtree, then the root node, and finally the ...
Approach
- Recursive Approach:
- Start from the root of the tree.
- Recursively traverse the left subtree.
- Visit the current node by adding its value to the result array.
- Recursive...
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