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Google·Software Engineer·Onsite - Multi Round·Intermediate

IntermediatePending
Jul 2026

Summary

Four rounds at Google for a software engineer role. Coding and behavioral screens went well per recruiter feedback, and the two onsite rounds were both graph-heavy. Came out of it unsure whether the bugs left in R3 would sink the whole thing.

Questions Asked (2)

Q1

Solve a difficult graph problem, deriving the optimal approach from scratch.

Algorithms & Data Structures
Author's notes

Got stuck pretty bad at the start.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints and edge cases, then systematically explore possible approaches from brute force to optimized, explaining trade-offs. Derive the optimal solution by identifying patterns, choosing appropriate data structures, and proving correctness and complexity.

Pro tip: Think aloud to demonstrate your problem-solving process, and explicitly state assumptions and invariants to show structured thinking. If stuck, simplify the problem or consider related known algorithms.

1. Understand and Clarify

Ask clarifying questions to fully understand the problem, including input/output format, constraints, edge cases, and expected complexity.

2. Explore Approaches

Brainstorm multiple approaches, starting with a brute-force solution, then optimize by identifying bottlenecks and applying known techniques (e.g., BFS, DFS, Dijkstra, Union-Find).

3. Derive Optimal Solution

Select the most promising approach, justify its correctness, and derive the algorithm step-by-step, considering data structures and their impact on time/space complexity.

4. Analyze Complexity

Clearly state the time and space complexity of your solution, and compare with alternatives to show why it's optimal.

5. Test and Validate

Walk through the algorithm with sample inputs, including edge cases, to verify correctness and identify potential bugs.

Key Points to Mention

  • Graph representation (adjacency list vs. matrix) and its impact on performance
  • Algorithm selection (BFS, DFS, Dijkstra, Bellman-Ford, topological sort, etc.) based on graph properties
  • Handling of edge cases: disconnected graphs, cycles, negative weights, large inputs
  • Time and space complexity analysis with Big-O notation
  • Proof of correctness or invariant maintenance
  • Potential optimizations like using priority queues, memoization, or bidirectional search

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

Q2

Solve a graph problem requiring a priority queue optimization, and analyze time and space complexity.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

This one went better.

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AI HintsAI Generated

Suggested Approach

First, clarify the problem and identify the graph structure and constraints. Then, explain how a priority queue (e.g., binary heap) optimizes the algorithm, such as in Dijkstra's or Prim's, and justify why it's better than alternatives. Finally, analyze time and space complexity, discussing trade-offs and potential optimizations.

Pro tip: Always discuss the trade-offs of using a priority queue versus other data structures, and mention real-world applications to show depth. Also, be prepared to code the solution and analyze complexity on the spot.

1. Clarify the Problem

Ask clarifying questions to understand the graph type (directed/undirected, weighted/unweighted), constraints, and expected output. Confirm if a priority queue is indeed required or if alternatives exist.

2. Outline the Algorithm

Describe the algorithm step-by-step, highlighting where the priority queue is used (e.g., extracting the minimum distance node). Explain why a priority queue is optimal for this operation.

3. Analyze Complexity

Derive time and space complexity, considering the priority queue operations (insert, extract-min) and graph traversal. Compare with naive approaches to show the benefit.

4. Discuss Trade-offs and Optimizations

Mention alternative data structures (e.g., Fibonacci heap) and their impact on complexity. Discuss edge cases and potential improvements.

5. Code and Test

If required, write clean code for the solution, and walk through a small example to verify correctness and complexity.

Key Points to Mention

  • Priority queue implementation (binary heap vs. Fibonacci heap) and its effect on time complexity
  • Time complexity: O((V+E) log V) with binary heap, O(E + V log V) with Fibonacci heap
  • Space complexity: O(V) for distances and priority queue, O(V+E) for graph representation
  • Correctness of greedy approach in algorithms like Dijkstra's
  • Handling of negative weights or cycles (if applicable)
  • Real-world applications (e.g., network routing, pathfinding)

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