SDE2 Interview Questions at Google

Given a binary tree, return the boundary of the tree in anti-clockwise direction starting from the root. The boundary consists of the left boundary, leaves, and the right boundary in reverse.

Design Google Search autocomplete. As a user types "wea", suggest "weather", "weather today", "weather London". Cover: trie vs inverted index, personalisation, freshness, latency budget (<100ms), and how you handle offensive query suggestions.

Design Google Maps ETA calculation. How do you compute the fastest route for 1B+ users in real time? Cover: graph representation of road network, Dijkstra vs A* vs Contraction Hierarchies, live traffic data ingestion, and how you handle road closures.

Explain how React's reconciliation algorithm decides what to re-render. A senior dev claims 'adding a key prop always makes things faster.' Is he right?

Explain gRPC vs REST API. When would you choose gRPC?

Implement a topological sort for a directed acyclic graph. Then extend it to detect cycles and explain how this maps to dependency resolution in build systems like Bazel.

Explain how a browser renders a web page from the moment the user presses Enter. Cover: DNS resolution, TCP handshake, HTTP request, HTML parsing, CSSOM, render tree, layout, paint, and compositing. Where would you optimise for Core Web Vitals?

How would you design and implement an autocomplete system? Focus on the data structure and ranking.

Your gRPC service has p99 latency of 1 second. Adding a timeout of 500ms seems to help p99 but now 1% of requests fail with DeadlineExceeded. What's the correct approach?

Implement a trie data structure. Your implementation must support: insert, search, and startsWith. Then optimize space for a dictionary with 1 million words.