Find connected components in binary tree

Last updated: April 6, 2026

Quick Overview

Given a binary tree, write a function to identify and return all connected components within the tree. A connected component is defined as a subset of nodes such that there exists a path between any two nodes in the subset. The output should be a list of lists, where each inner list contains the nodes of a connected component.

Anthropic
Coding & Algorithms
Machine Learning Engineer
Anthropic
April 6, 2026
Machine Learning Engineer
Onsite
Coding & Algorithms
Medium

10

9

712 solved


Given a binary tree, write a function to identify and return all connected components within the tree. A connected component is defined as a subset of nodes such that there exists a path between any two nodes in the subset. The output should be a list of lists, where each inner list contains the nodes of a connected component.

This coding problem is frequently asked during Onsite at Anthropic. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Anthropic 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
Data structure selection and trade-offs
Dynamic programming and memoization
Binary search and divide and conquer
Tree structures and recursion
Edge cases and input validation
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • What is the worst-case input for your solution?
  • Can you solve this iteratively instead of recursively (or vice versa)?
  • What if the input doesn't fit in memory?
  • Can you solve this in a single pass?
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Sample Answer
Problem Analysis

To solve the problem of finding connected components in a binary tree, we can recognize that the tree structure naturally forms connected components, as each node is linked to its children. Since bina...

Approach

The approach involves a depth-first search (DFS) or breadth-first search (BFS) to traverse the entire binary tree and collect nodes into a list. Here’s a step-by-step algorithm using DFS:

  1. Define a ...

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