Uber Frontend Interview Experience

An online assessment was conducted on the CodeSignal platform.
• 𝟮 𝗰𝗼𝗱𝗶𝗻𝗴 𝗽𝗿𝗼𝗯𝗹𝗲𝗺𝘀
• 𝟴 𝗺𝘂𝗹𝘁𝗶𝗽𝗹𝗲-𝗰𝗵𝗼𝗶𝗰𝗲 𝗾𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀

𝗗𝗶𝘀𝗰𝘂𝘀𝘀𝗶𝗼𝗻 𝗼𝗻 𝗣𝗮𝘀𝘁 𝗣𝗿𝗼𝗷𝗲𝗰𝘁𝘀

1. Performance optimizations
2. Challenges faced in previous projects

𝗠𝗮𝗰𝗵𝗶𝗻𝗲 𝗖𝗼𝗱𝗶𝗻𝗴 𝗣𝗿𝗼𝗯𝗹𝗲𝗺

1. Implement a 𝗚𝗿𝗶𝗱 𝗟𝗶𝗴𝗵𝘁 𝗕𝗼𝘅 with all possible edge cases.

𝗣𝗮𝘀𝘁 𝗣𝗿𝗼𝗷𝗲𝗰𝘁 𝗗𝗶𝘀𝗰𝘂𝘀𝘀𝗶𝗼𝗻.

𝗣𝗿𝗼𝗯𝗹𝗲𝗺-𝗦𝗼𝗹𝘃𝗶𝗻𝗴 𝗧𝗮𝘀𝗸: Implement a memoization function for an asynchronous function.

async function getUserData(q, key, cb) {
fetch(`localhost:3000/get/users?query=${q}&key=${key}`)
.then(res => HTTPResponse(res, cb));
}

let memoFun = memoizeUserData(getUserData);
memoFun('test', 100, callback);

𝗙𝗼𝗹𝗹𝗼𝘄-𝘂𝗽 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀:
• How would you handle JSON input as a parameter?
• If two JSON objects have the same keys but in a different order, how would it work?
• If the above four API calls are made in parallel, will there be a single API call or all four?

High-Level Design (HLD) of "𝘞𝘩𝘢𝘵𝘴𝘈𝘱𝘱 𝘞𝘦𝘣"

• Shared a screenshot of the current WhatsApp Web main page.
• Discussed chatting protocols.
• Explored API design, including functions, payload structure, and efficiency.
• Questions on pagination, caching strategies, and scalability.

𝟭. 𝗣𝗮𝘀𝘁 𝗽𝗿𝗼𝗷𝗲𝗰𝘁 𝗱𝗶𝘀𝗰𝘂𝘀𝘀𝗶𝗼𝗻.
𝟮. 𝗕𝗲𝗵𝗮𝘃𝗶𝗼𝗿𝗮𝗹 𝗤𝘂𝗲𝘀𝘁𝗶𝗼𝗻𝘀:
• How did you handle disagreements with a PM, designer, or colleague?
• Why do you want to join Uber?
• What improvements would you suggest for Uber?
• Other general behavioral and leadership-related questions.

𝗣𝗮𝘀𝘁 𝗣𝗿𝗼𝗷𝗲𝗰𝘁 𝗗𝗶𝘀𝗰𝘂𝘀𝘀𝗶𝗼𝗻.

𝗣𝗿𝗼𝗯𝗹𝗲𝗺-𝗦𝗼𝗹𝘃𝗶𝗻𝗴 𝗧𝗮𝘀𝗸: 𝘡𝘰𝘮𝘣𝘪𝘦 𝘚𝘱𝘳𝘦𝘢𝘥 𝘪𝘯 𝘢 𝘊𝘰𝘶𝘯𝘵𝘳𝘺

Given a matrix where:

• 2 - infected city
• 1 - vulnerable city
• 0 - uninhabitable land
• Every infected city spreads the infection to all adjacent cities (up, down, left, right) in one day.

Calculate how many days it takes to infect the entire habitable area.

Sample test case:

𝗜𝗻𝗽𝘂𝘁:
2 1 1
1 1 0
0 1 1
𝗢𝘂𝘁𝗽𝘂𝘁: 3 days