Software Test Engineer, Google Pixel

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 cache. Consider the following requirements: Basic Functionality: Implement a cache with put(key, value) and get(key) methods. Eviction Policy: Implement an LRU (Least Recently Used) eviction policy. When the cache is full, the least recently accessed item should be evicted to make space for the new item. Thread Safety: Ensure the cache is thread-safe to handle concurrent access from multiple threads. Generics: The cache should be able to store any type of key and value (using generics). Time Complexity: get and put operations should have an average time complexity of O(1). Example Usage: Cache cache = new Cache(5); // Cache with capacity 5 cache.put(1, one); cache.put(2, two); cache.get(1); // Access key 1, moves it to the most recently used cache.put(3, three); cache.put(4, four); cache.put(5, five); cache.put(6, six); // This will evict key 2 (LRU) System.out.println(cache.get(2)); // Output: null (because it was evicted) Discuss the data structures you would use, the implementation details for each method, and how you would address thread safety.

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.