10+ United Airlines Interview Questions and Answers

I participated in a coding challenge that tested JavaScript concepts like currying and object flattening.

• The coding challenge involved implementing a function that demonstrates currying in JavaScript.

• Another part of the challenge required flattening nested objects using recursion.

• I used higher-order functions and closures to achieve currying in the challenge.

• The challenge also tested my understanding of object manipulation and traversal in JavaScript.

Use a hashmap to store seen elements and check if complement exists in the hashmap.

• Create a hashmap to store seen elements.

• Iterate through the array and for each element, check if the complement (k - current element) exists in the hashmap.

• If complement exists, return the pair of integers.

• Example: For array [2, 7, 11, 15] and sum 9, the pair of integers is (2, 7).

useMemo is used to memoize a value, while useCallback is used to memoize a function.

• useMemo is used to optimize expensive calculations by caching the result.

• useCallback is used to optimize the rendering of child components by memoizing event handlers.

• useMemo returns the cached value, while useCallback returns the memoized function.

• Both hooks take a dependency array to determine when to recalculate or re-render.

Anagrams of a string are words or phrases formed by rearranging the letters of the original string.

• Create a hashmap to store the frequency of characters in the input string

• Iterate through the array of strings and check if the frequency of characters matches with the input string

• Add the strings that are anagrams of the input string to the result array

Low level design machine coding involves writing detailed code for specific functions or algorithms.

• Identify the specific functionality or algorithm to be implemented

• Break down the functionality into smaller components

• Write detailed code for each component, considering efficiency and optimization

• Test and debug the code to ensure it works as expected

Progress bar in React can be designed using CSS and state management.

• Use CSS to style the progress bar

• Use state management to update the progress value dynamically

• Consider using libraries like react-progress-bar to simplify implementation

useState is a hook in React that allows functional components to manage state.

• useState is a built-in hook in React.

• It allows functional components to have stateful logic.

• useState returns an array with two elements: the current state value and a function to update it.

• The initial state value is passed as an argument to useState.

• The state value can be of any data type, including objects and arrays.

• The update function returned by useState can be called to modify the state value.

• C...read more

useEffect is a React Hook used to perform side effects in functional components.

• useEffect is used to handle side effects like data fetching, subscriptions, or manually changing the DOM.

• It takes two arguments: a function that contains the side effect logic, and an optional array of dependencies.

• The function inside useEffect is executed after the component renders and after every update, unless dependencies are specified.

• If dependencies are provided, the effect will only be re-...read more

Design Uber supplier dispatch

• Create a system to match drivers with riders based on location and availability

• Use real-time data to optimize dispatching and reduce wait times

• Implement a rating system to ensure quality service from drivers

• Integrate with payment and mapping systems for seamless user experience

Implement tree traversal algorithm to visit each node in a tree structure

• Use depth-first search (DFS) or breadth-first search (BFS) to traverse the tree

• DFS can be implemented using recursion or a stack data structure

• BFS can be implemented using a queue data structure

• Example: Inorder traversal of a binary tree - left, root, right

An in-memory database is a database that primarily relies on main memory for data storage and retrieval.

• Utilize data structures like hash tables or trees for fast data access

• Implement caching mechanisms to optimize performance

• Consider data persistence strategies for durability

• Support for transactions and concurrency control

• Example: Redis, Memcached

Design a notification service for sending alerts to users.

• Use a scalable messaging system like Kafka or RabbitMQ to handle high volume of notifications.

• Implement a user subscription system to allow users to choose which notifications they want to receive.

• Include different channels for notifications such as email, SMS, and push notifications.

• Consider implementing a scheduling system to send notifications at specific times.

• Ensure notifications are personalized and relevant to e...read more

Splitwise is a bill splitting application where users can track and split expenses with friends.

• Design classes for User, Expense, Group, and Transaction

• Implement functions for adding expenses, settling debts, and generating reports

• Consider scalability and data storage options like databases

• Handle currency conversions and real-time updates for balances

In React JS, timers can be implemented using setInterval or setTimeout functions.

• Use setInterval for recurring timers

• Use setTimeout for one-time timers

• Remember to clear the timer using clearInterval or clearTimeout when component unmounts