CareerCup

Design payments system like Google Pay or Paytm.

Design QR code system for a grocery shop.

You have a bit pattern and an infinite stream of bits coming in. You need to raise an alarm whenever the given pattern comes. Storing the stream is not allowed.

Design a Notification Service. Notification can be sent to multiple devices.

Design a job workflow system wherein a job is defined as sequence of steps. This system will take jobs and execute as per the steps in job. The steps can be conditional(if this then do this else do that). This system should be able to handle multiple jobs, should be fault tolerant etc

Design and implement a Message broker which can handle high throughput and is fault tolerant.

Design a workflow system. You need to implement pause/continue operations of the workflow using your database. Essentially, the interviewer was looking completely manage workflow system using database.

Design a finite state machine

Design slack like collaboration tool

There is a notepad which accepts only four operations:
1. Character X
2. select all
3. copy
4. paste
Given n number of operations, provide the sequence of choices that gives maximum characters in the notepad.

Given two async streams -
Trip : {tripId, date, city}
Bill: {billId, tripId, date, amount}

Design a system to get real time aggregated view of following nature
City, TripCount, TotalAmount

Events in both streams can be out of sync or duplicate. But result needs to be accurate and realtime.

Design a Scheduler Service which can handle high throughput with minimal latency. Should be fault-tolerant and distributed.

Design a log4j style logging library for a high throughput multi threaded application.

Parking lot problem: Given 3-dimensional parking lot, lets say, length width and floor. Implement following two methods:
void unpark(int i, int j, int k); where i, j, k are the parking coordinates.
void park(); The car should be parked in empty cell with lowest floor and between length and breadth prefer minimum length.Example, (3, 4, 2) is preferred over (1, 1, 3) as floor is 2 in first case. (1, 2, 3) is preferred over (2, 1, 3). (2, 3, 3) is preferred over (2, 4, 3).

Given an array find if array gets sorted by reversing any subarray of this array. Ex: In {1, 2, 3, 4, 8, 7, 6, 9} we can reverse subarray from index 4 to 6.

LLD for third party delivery vendor for registration and notification system.

Design gaming platform. A number of games can be hosted on this platform. User can login and select a particular game.

Design Meeting calendar system. Then there was discussion on various issues on it like scalability, what database should be used; SQL-NoSQL, concurrency etc.

You are given many files of 6 GB, each having stream of integers. You have space of 4 GB left in your main memory (mainly to swap out, swap in). You have to store sorted sequence of integers in all file in a other output file. How will you do that?

Design an authentication using AWS services like Api gateway and lambda.

Design an online chess game.

It supports 3 mode:
Player vs. AI
Player vs. player  (Offline)
Player vs, player (Online)

The questions asked were how will you assign a player to another player who wants to play. You need to think about how to divide your players into multiple groups of ratings, so that a newbie is not playing a grand master, rather with someone who is of his level only. Then the question was how will you design your system when a player comes in and say I want to play, and the max wait time is 1 min, you need to find a player suitable for his level

Design a movies reviews aggregator system. Data should be fetched from movie rating providers like imdb, rotten tomatoes, etc

Find the sum of n elements after a kth smallest element in BST. Tree is very large, you are not allowed to traverse the tree.

Design subscription based sports website which can display scores, game status, history for any games hld and lld

Consider an infinite stream of numbers. At any point print smallest k elements.

Given an array of integers(duplicates allowed) return if it is a set of contiguous integers or not?
Input: 5,2,3,6,4,4,6,6 Output: Yes (as it is from set of [2,3,4,5,6])

Given an array of integers with the property that arr[j] – arr[j-1] is either 1,0,-1 and a search value, provide an efficient search mechanism.

Given coin denomination of 3, 6 and 17, find the number of ways in which you can form a sum 'n'. How will do it for large numbers?

There is a huge road. Given are the following
- Array D that stores the distance from a starting point where billboard can be installed.
- Array C that stores the profit. C[i] -> profit if the billboard is installed at distance D[i].
- dist -> minimum distance to maintain between the billboards.

Assume you can install any number of billboards while maintaining a given minimum distance 'dist' between each of them. Find the maximum profit you can achieve.

Design an airport service that will be used to allocate a free runway when the plane is about to land. Data structure for the same. What if the runway is not available? Message passing between control centre and the plane. Focus on low-level design and code. Can the same runway be alloted to two different planes (locking)? Database storage needed?