Greedy on binary tree
Last updated: July 27, 2025
Quick Overview
Given a binary tree, implement a greedy algorithm to find the maximum sum of values from the root to any leaf node, where you can only move to child nodes. The input will be the root node of the binary tree, and the output should be the maximum sum as an integer.
Brex
July 27, 2025436
11
1,670 solved
Given a binary tree, implement a greedy algorithm to find the maximum sum of values from the root to any leaf node, where you can only move to child nodes. The input will be the root node of the binary tree, and the output should be the maximum sum as an integer.
Brex uses this problem in the Phone Screen 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
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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
- Can you optimize the space complexity of your solution?
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of finding the maximum sum from the root to any leaf node in a binary tree, we can utilize a Depth-First Search (DFS) approach. This is because the problem inherently involves exp...
Approach
- Start at the root node and initialize a variable to keep track of the maximum path sum.
- Define a recursive function that takes the current node and the current sum as parameters.
- At each nod...
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