Google L3 Fresh Grad Onsite: Three Coding Rounds and BQ

Role: Software Engineer, L3 / Fresh Grad
Result: Passed the interview stage
Report time: November 2025
Application: Referral

Coding round 1

Problem 1: count islands

The candidate received a list of linked-list nodes representing islands and had to return the number of islands.

They started with Union-Find. The interviewer then asked for the optimal approach. The original report did not preserve the complete input model, so details beyond the linked-list representation remain unclear.

Practice: Count Islands Represented by Linked Lists

Problem 2: constant-time putAll

Implement a CoolMapInterface supporting:

• put(key, value)
• get(key)
• putAll(value)

The important constraint was that putAll had to update the value associated with every key in O(1) time.

Practice: Design a Map With Constant-Time PutAll

Behavioral interview

One scenario asked what the candidate would review in a photo-processing project to avoid offending users. The interviewer said there was no single correct answer and continued with edge-case follow-ups.

Other questions focused on the candidate's relationship with a manager and what they had learned from that manager.

Coding round 2: exactly one person online

Given online-time intervals for different people, return the periods when exactly one person was online.

Practice: Find Intervals With Exactly One Person Online

Coding round 3

The source preserved only the word “Dijkstra.” It did not include enough information to reconstruct the prompt, inputs, output, or follow-ups.