Software Engineer III, Infrastructure, 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. This is a crucial component in many systems to prevent abuse and ensure fair usage. Your rate limiter should meet these requirements: Functionality: It should limit the number of requests a user can make within a specific time window. For example, allow a user to make 10 requests per minute. Scalability: The rate limiter needs to handle a large number of users and requests concurrently. Imagine millions of users accessing the system. Accuracy: It should accurately track and enforce the rate limits. A small degree of error is acceptable, but significant deviations are not. Low Latency: The rate limiter must not introduce significant delays in request processing. The overhead should be minimal. Fault Tolerance: The system should continue to function correctly even if some components fail. It should be resilient to outages. Cost-Effectiveness: The solution should be cost-effective in terms of resources used (e.g., memory, CPU, network bandwidth). Consider these scenarios and constraints: Users are identified by a unique ID. The time window is configurable (e.g., seconds, minutes, hours). The rate limit is also configurable per user or group of users. You can use any data structures and algorithms you deem appropriate. Assume you have access to a distributed cache (e.g., Redis, Memcached). Walk me through your design. Discuss different approaches, their trade-offs, and how you would address the requirements. Specifically, consider the following: Data structures for storing request counts. Algorithms for incrementing and checking request counts. Handling concurrency and race conditions. Strategies for distributing the rate limiter across multiple servers. How to handle exceeding the rate limit (e.g., returning an error code). Monitoring and alerting. For example, if a user with ID user123 tries to make 11 requests within a minute when their limit is 10, the rate limiter should reject the 11th request. How would your system achieve this efficiently and reliably at scale?

Google

Tell me about a time you had to sign a non-disclosure agreement (NDA). What were the key terms, and how did you ensure compliance while working on the project? Consider these points in your answer: Context: Briefly describe the project and the purpose of the NDA. Who were the parties involved, and what information was being protected? Key Terms: What were the most important clauses or restrictions outlined in the NDA? This could include limitations on sharing information, reverse engineering, or using the protected information for purposes outside the scope of the agreement. Compliance Measures: What specific steps did you take to ensure you and your team complied with the NDA? Did you implement any specific procedures, such as data encryption, access controls, or regular training? Challenges: Did you face any challenges in adhering to the NDA? If so, how did you overcome them? Did you need to seek clarification on any terms or consult with legal counsel? Outcome: What was the result of the project, and how did the NDA contribute to its success? Did the NDA effectively protect the confidential information, and were there any lessons learned from the experience? For example, perhaps you worked on a project involving a new algorithm for a company. The NDA might have restricted you from sharing the algorithm with anyone outside the project team, reverse engineering it, or using it for any other projects. You might have implemented access controls to limit who could access the algorithm's source code and conducted regular training sessions to remind the team of their obligations under the NDA. You should talk about how you proactively avoided violations and made sure your actions were fully within the legal scope of the agreement.