Find maximum path in binary tree
Last updated: December 27, 2025
Quick Overview
Given a binary tree, find the maximum path sum, where the path may start and end at any node in the tree. The path sum is defined as the sum of the values of the nodes along the path. Return the maximum path sum as an integer.
Netflix
December 27, 202526
14
4,904 solved
Given a binary tree, find the maximum path sum, where the path may start and end at any node in the tree. The path sum is defined as the sum of the values of the nodes along the path. Return the maximum path sum as an integer.
This coding problem is frequently asked during Take-home Project at Netflix. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Netflix 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 if the input doesn't fit in memory?
- What is the worst-case input for your solution?
- Can you optimize the space complexity of your solution?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To tackle the problem of finding the maximum path sum in a binary tree, we can use a Depth-First Search (DFS) approach. The reason DFS is suitable here is that we need to explore all possible paths st...
Approach
The algorithm can be broken down into the following steps:
- Create a recursive helper function that computes the maximum path sum for each node.
- For each node, compute the maximum contribution th...
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