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Google·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jul 2026

Summary

Google SWE coding round, one question about tree/graph traversal dressed up as a chicken family problem. Cute framing but the core is just figuring out if two nodes are connected in a directed graph.

Questions Asked (1)

Q1

Given a dictionary of parent-child relationships between chickens, write a function that determines whether two given chickens share any familial connection.

Algorithms & Data Structures
Author's notes

The chicken theme threw me for a second and I almost laughed, but it's really just 'are these two nodes connected in a directed graph.' I went with BFS from both nodes and checked for overlap in their ancestor/descendant sets.

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AI HintsAI Generated

Suggested Approach

Model the relationships as a graph and determine if two nodes are connected. Use union-find for efficient connectivity queries or BFS/DFS to traverse from one chicken to the other. Clarify assumptions about the dictionary structure and whether the graph is a tree or a general graph.

Pro tip: Discuss trade-offs between union-find and traversal: union-find is ideal for multiple queries, while BFS/DFS is simpler for a single query. Mention that if the graph is a tree, you can find the root and compare paths, but union-find handles general graphs.

1. Clarify the problem

Ask about the dictionary format (e.g., parent -> list of children), whether the graph is directed or undirected, if it's a tree or a general graph, and if there are multiple queries.

2. Choose an approach

Decide between union-find (for multiple queries) and BFS/DFS (for a single query). Consider building an undirected graph if relationships are bidirectional.

3. Implement the solution

For union-find, initialize each chicken as its own set, union all parent-child pairs, then check if the two chickens have the same root. For BFS/DFS, build an adjacency list and search from one chicken to the other.

4. Analyze complexity

Union-find with path compression and union by rank: O(α(N)) per operation, nearly constant. BFS/DFS: O(V+E) time and space. Discuss trade-offs.

5. Test with examples

Walk through a simple example, including edge cases like same chicken, disconnected components, and cycles if applicable.

Key Points to Mention

  • Graph representation: adjacency list or union-find data structure
  • Union-find with path compression and union by rank for efficiency
  • BFS/DFS traversal for connectivity check
  • Handling directed vs undirected relationships
  • Time and space complexity analysis
  • Edge cases: same chicken, no connection, cycles, multiple components

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.