UI Engineer (L5), Ads Platform Engineering

Netflix

You are given the definition of a binary tree node: class Node: def init(self, val=0, left=None, right=None): self.val = val self.left = left self.right = right Write a function is_bst(root) that takes the root of a binary tree as input and returns True if the tree is a valid Binary Search Tree (BST), and False otherwise. Definition of a BST: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys greater than the node's key. Both the left and right subtrees must also be binary search trees. Example 1: Input: root = [2,1,3] Output: true 2 / 1 3 Example 2: Input: root = [5,1,4,null,null,3,6] Output: false 5 / 1 4 / 3 6 Explanation: The root node's value is 5 but its right child's value is 4. Constraints: The number of nodes in the tree is in the range [1, 10000]. -10000 <= Node.val <= 10000 Your solution should handle edge cases such as an empty tree or a tree with only one node.

Netflix

High-Level Design for Zero-Downtime Live Production Systems Imagine you're tasked with designing a live production system that requires zero downtime during deployments and updates. This system handles a large volume of requests and is critical to the business. Let's consider a scenario: Scenario: You are building a service that provides real-time stock quotes to users. The service needs to be highly available and scalable to handle peak loads. Deployments must not interrupt the service, ensuring users always receive the latest data. Questions to address in your design: High-Level Architecture: Describe the overall architecture of the system. Include key components, their responsibilities, and how they interact. Deployment Strategy: Detail the deployment strategy you would use to achieve zero downtime. Explain the steps involved in deploying new versions of the service. Load Balancing: How would you distribute traffic across different instances of the service to ensure high availability and prevent overload? Monitoring and Rollback: What monitoring tools and metrics would you use to detect issues during deployment? Describe the rollback strategy in case of a failed deployment. Data Consistency: How would you ensure data consistency across different instances of the service during updates? Scaling: How would you scale the system horizontally to handle increased traffic? Explain each of these areas with consideration to both the design and the practical steps required for running such a system in live production. Consider specific technologies and tools where appropriate to illustrate your understanding. This question aims to assess your understanding of designing and operating highly available systems, your knowledge of deployment strategies, and your ability to handle real-world challenges in a production environment.

Netflix

Describe a time when you had a deadline you couldn't meet. What did you do, and what was the outcome? For example, imagine you were tasked with developing a new feature for a popular mobile app with a launch date tied to a major industry event. Due to unforeseen technical complexities or resource constraints, it became clear that you wouldn't be able to deliver the complete feature set by the deadline. How did you communicate this to your team and stakeholders? What steps did you take to mitigate the impact of the missed deadline? Did you try to renegotiate the scope or timeline? How did you prioritize the remaining tasks, and what alternative solutions did you explore to deliver value within the limited timeframe? What did you learn from this experience, and how did it influence your approach to project management and deadline setting in subsequent projects?