**Round 1: Written test**** with 2 questions**

Question1: Given an array of size n containing both positive and negative numbers. Find the count of subarrays whose sum is 0.

Question2: Add next pointer to every node present at the same level.

**Round 2: Data structures and Algorithm**

First discussion on my approach and code for the written test problems

Question 1: https://www.geeksforgeeks.org/minimum-number-platforms-required-railwaybus-station/

Question 2: Given a chess board of size m*n. A knight is present at some initial position. Find the minimum number of moves so that it can move to some given final location.

Hint: Think BFS

**Round 3: Algorithm, Design and OOPS concepts**

Question 1: Design a tank game. https://www.youtube.com/watch?v=ms-MTSCF3mw

HLD and LLD with classes and functionalities. Design patters, abstract classes and interfaces

Question 2: A continuous stream of numbers is coming. Find the median at any given time. Algorithm and code

Hint: Lets say m is a median at any given time. Use a min heap of numbers more than m and a max heap of numbers less than m. Now retrieval is O(1) and insertion is O(log n)

Question 3: Design whatsapp. Just high level design

Question 4: How deployment works on multiple server machines. Concepts of AB testing and few other questions

**Round 4: Algorithm, Design, multi threading, concurrency, database concepts**

Question 1: Given a string of characters. You need to transform it to a given new string of same length in minimum cost where:

a) ‘b’ can be transform to ‘a’ or to ‘c’ with cost 1. Similarly for other characters.

b) any numbers of b’s can be transformed to c’s with cost 1 and also to a’s with cost 1.

Question 2: Given multiple bars of given heights and unit width. Find the rectangle with max area.

Question 3: Design a vending machine

Question 4: How will you choose which column to choose for indexing.

Question 5: Sharding in databases. How facebook would shard it users database

Questions on mulithreading, immutable class, concurrency

**Round 5: Design, Previous experience and practical questions**

Question 1: Explain any 1 project I enjoyed working on

Interviewer was not interested in my project and moved to a design question

Question 2: Design a traffic signal starting with all use cases, HLD, LLD

Question 3: Design an elevator system

My favorite design patterns and what patterns I would use in above questions

What I would look in design reviews and in code reviews and few other behavioral questions

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.