Principal Engineer, Mobile, Rider

Uber

Given a 2D grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. For example, consider the following grid: 11110 11010 11000 00000 This grid has 1 island. Now, consider this grid: 11000 11000 00100 00011 This grid has 3 islands. Your task is to write a function that takes a 2D grid (represented as a list of lists of characters) as input and returns the number of islands in the grid. Constraints: m == grid.length n == grid[i].length 1 <= m, n <= 300 gridi is '0' or '1'.

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

Describe a time you disagreed with your team members.