Senior Staff Software Engineer, Google Cloud

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

Can you describe a time you had to work with a difficult team member and how you handled the situation? This is a common behavioral interview question designed to assess your interpersonal skills, conflict resolution abilities, and ability to work effectively in a team environment, even when faced with challenges. When answering this question, it's crucial to provide a specific example, detailing the situation, your actions, and the resulting outcome. This allows the interviewer to understand your approach and evaluate your effectiveness. For instance, you might discuss a project where a team member consistently missed deadlines, hindering the team's progress. In your response, you should: Describe the Situation: Clearly outline the project, the team member's role, and the specific behaviors that made them difficult to work with (e.g., missed deadlines, lack of communication, negative attitude). Be objective and avoid accusatory language. Explain Your Actions: Detail the steps you took to address the situation. Did you have a one-on-one conversation with the team member? Did you involve a supervisor or mentor? Did you try to understand the reasons behind their behavior? Did you adjust your own approach to accommodate their needs? Highlight the Result: Explain the outcome of your actions. Were you able to resolve the issue? Did the team member improve their performance? What did you learn from the experience? Even if the outcome wasn't ideal, focus on the lessons learned and how you would approach a similar situation in the future. Remember, the STAR method (Situation, Task, Action, Result) can be a helpful framework for structuring your answer. The interviewer wants to see that you can navigate challenging interpersonal dynamics professionally and contribute to a positive team environment.