Staff Software Engineer, Backend, ML

Uber

You are given an array of integers nums and an integer target. Problem: Write a function twoSum that finds two distinct numbers in the nums array that add up to the target. The function should return an array containing the indices of the two numbers. If no such pair exists, return an empty array. Example: nums = [2, 7, 11, 15] target = 9 twoSum(nums, target) == [0, 1] // Because nums[0] + nums[1] == 2 + 7 == 9 nums = [3, 2, 4] target = 6 twoSum(nums, target) == [1, 2] // Because nums[1] + nums[2] == 2 + 4 == 6 nums = [3, 3] target = 6 twoSum(nums, target) == [0, 1] // Because nums[0] + nums[1] == 3 + 3 == 6 Constraints: 2 <= nums.length <= 104 -109 <= nums[i] <= 109 -109 <= target <= 109 Only one valid answer exists. Follow-up: Can you come up with an algorithm that is less than O(n^2) time complexity?

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.