Staff Software Engineer, Mobile (Android), Geo

Google

Given n pairs of parentheses, what is the total number of different, valid combinations of those parenthesis? For example: For n = 1, the only valid combination is (), so the answer is 1. For n = 2, the valid combinations are ()() and (()), so the answer is 2. For n = 3, the valid combinations are ((())), (()()), (())(), ()(()), and ()()(), so the answer is 5. Calculate the number of valid parenthesis combinations for a given n. Explain the formula or method used to arrive at the answer. What is the underlying mathematical concept at play here, and how does it ensure that we only count valid combinations, avoiding invalid ones such as )()(? Detail the relationship between this problem and Catalan numbers, and discuss how this relationship can be utilized to efficiently compute the number of valid combinations, even for relatively large values of n.

Google

Let's design a rate limiter for an API. The rate limiter should: Limit the number of requests a user can make to an API within a given time window. Support different rate limits for different users or API endpoints. For example, a free tier user might be limited to 10 requests per minute, while a premium user can make 100 requests per minute. Similarly, some API endpoints might have lower rate limits than others due to resource constraints. Be highly performant to avoid adding significant latency to API requests. Be scalable to handle a large number of users and API requests. Be reliable and prevent accidental overloads that could cause service disruptions. Describe the architecture, algorithms, and data structures you would use to implement such a rate limiter. Consider the following: How would you store the rate limit counters for each user or endpoint? What algorithm would you use to determine whether a request should be allowed or throttled? How would you handle distributed rate limiting across multiple servers? How would you ensure the rate limiter is resilient to failures? As an example, imagine a scenario where a social media platform wants to prevent users from spamming their API with excessive requests to post updates. The platform has millions of users and thousands of API endpoints. Some users pay for premium access with higher request limits. How would you design a robust and efficient rate limiter to handle this scale and these varying requirements?

Google

Why do you want to work for Google? To provide a more comprehensive answer, consider these points: Google's Mission and Values: How do Google's mission to organize the world's information and make it universally accessible and useful align with your own values and career aspirations? Can you provide specific examples of Google's products or initiatives that resonate with you and explain why? Google's Culture of Innovation: Google is renowned for its innovative culture. What aspects of this culture appeal to you most? For instance, are you drawn to Google's emphasis on experimentation, its commitment to open-source projects, or its support for employee creativity through initiatives like 20% time? How do you believe you would contribute to and thrive in such an environment? Opportunities for Growth and Learning: Google offers numerous opportunities for professional development and learning. Are there specific technologies, teams, or projects at Google that you are particularly interested in? Have you researched specific Google teams doing work that aligns with your interests and skills? How do you envision your career progressing at Google, and what skills or knowledge do you hope to gain? Impact and Scale: Google's products and services have a global impact, reaching billions of users. How does the opportunity to work on projects with such a wide reach motivate you? Can you provide examples of how you would approach challenges related to scalability, reliability, and user experience in a global context? Specific Skills and Contributions: What specific skills and experiences do you bring that would make you a valuable asset to Google? Highlight your technical expertise, problem-solving abilities, teamwork skills, and any relevant accomplishments. For example, can you discuss a time when you successfully tackled a challenging technical problem or collaborated effectively on a complex project? By addressing these points with specific examples and demonstrating a genuine interest in Google's mission, culture, and opportunities, you can provide a compelling and insightful answer to the question of why you want to work there.