Engineering Manager, Ads Quality Infra, Data Observability

Google

Given a tree data structure, and a set of nodes within that tree, how do you find all of their common parents? For example, consider a tree where node A is the root, and it has children B and C. Node B has children D and E, and node C has a child F. If the input set of nodes is {D, E, F}, then the common parents would be {B, C, A}. If the input set of nodes is {D, E}, then the common parents would be {B, A}. Design an algorithm to efficiently find these common parents, considering potential optimizations for different tree structures and sizes.

Google

Let's build an infinite scroll web page. Describe the key components, implementation details, and optimization strategies you would employ to create a smooth and efficient user experience. To clarify the requirements, imagine you are tasked with displaying a large dataset of images fetched from a remote server. The goal is to load and render these images as the user scrolls down the page, providing a seamless browsing experience without overwhelming the browser or causing performance issues. Specifically, address the following: Data Fetching: How would you handle fetching data in chunks from the server? What API endpoints and request parameters would you use? Consider how to manage the loading state to provide visual feedback to the user. Rendering: What techniques would you use to efficiently render the images? Consider the use of virtual DOM, lazy loading, and image optimization techniques. Scroll Handling: How would you detect when the user has scrolled to the bottom of the page and needs more data to be loaded? How would you prevent multiple requests from being triggered simultaneously? Performance Optimization: What strategies would you implement to optimize the performance of the infinite scroll? Consider techniques such as debouncing scroll events, caching data, and preloading images. Error Handling: How would you handle errors that might occur during data fetching or rendering? How would you display error messages to the user? Provide code snippets (in JavaScript, React, or any other relevant language) to illustrate your approach. Discuss any potential challenges or trade-offs involved in implementing an infinite scroll and how you would address them.

Google

Describe a time you faced a tough technical problem. What made it so difficult, and how did you approach solving it? What resources did you consult, and what was the final outcome? What did you learn from this experience, and how has it shaped your problem-solving skills since then? For example, perhaps you were tasked with optimizing a slow-running query in a large database. The initial attempts to improve performance, such as adding indexes, didn't yield the desired results. You then had to dive deep into the query execution plan, identify bottlenecks, and rewrite the query using more efficient techniques, like leveraging window functions or temporary tables. You could also describe the challenges faced while integrating a new feature into a legacy system with poorly documented code. You might have had to reverse engineer parts of the system, deal with unexpected dependencies, and carefully test the integration to avoid breaking existing functionality. Elaborate on the specific tools and methodologies you employed during these challenges, such as debuggers, profilers, or version control systems. Also, explain how you collaborated with team members or sought assistance from external resources like online forums or documentation to overcome the obstacles.