Software Engineer II, Backend - Delivery Platform

Uber

Given a binary tree where each node has a value and each node's value is either equal to the value of its parent or strictly greater than the value of its parent, find the second smallest value in the tree. The smallest value will be the root node value. If no second smallest value exists, return -1. For example, consider the following binary tree: 2 / 2 5 / / 5 7 5 7 In this case, the smallest value is 2. The next smallest value is 5. Therefore, the function should return 5. Consider another example: 2 / 2 2 / / 2 2 2 2 Here, all node values are 2. There is no second smallest value. The function should return -1. Constraints: The number of nodes in the tree is in the range [1, 1000]. 0 <= Node.val <= 2^31 - 1 root.val is always the smallest value in the tree.

Uber

Let's design a room reservation system. Consider the following requirements: Users: The system should allow users to search for available rooms and make reservations. Rooms: Each room has a capacity, a list of available equipment (e.g., projector, whiteboard), and a location. Reservations: Reservations have a start time, an end time, a room, and a user. Conflicts: The system must prevent double-booking of rooms. If someone tries to book a room that is already booked during that timeframe, they should receive an error message. Searching: Users should be able to search for rooms based on criteria such as capacity, available equipment, location, and time slot. Admin: Admins should be able to add new rooms, modify room details, and view all reservations. Consider the data models, APIs, and system architecture. Provide a high-level overview of your design, including the key components and their interactions. What data structures would you use to efficiently store and retrieve room and reservation information? How would you handle concurrency and prevent race conditions when multiple users try to book the same room simultaneously? What are the trade-offs between different architectural choices (e.g., monolithic vs. microservices)? What API endpoints would you expose for common operations like searching for rooms, creating reservations, and canceling reservations? How would you handle edge cases such as overlapping reservations or invalid user input? What database technology would you use and why?

Uber

Tell me about yourself and describe your past experiences in detail, focusing on specific accomplishments and challenges you faced.