OYO Rooms Interview Experience | Set 5 (For SDE2)
Round 1: Written test with 2 questions
- Given an array of size n containing both positive and negative numbers. Find the count of subarrays whose sum is 0.
- 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
- Minimum number of platforms required for railway-bus station
- 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
- Design a tank game.
HLD and LLD with classes and functionalities. Design patters, abstract classes and interfaces
- 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)
- Design whatsapp. Just high level design
- 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.
- Given multiple bars of given heights and unit width. Find the rectangle with max area.
- Design a vending machine
- How will you choose which column to choose for indexing.
- Sharding in databases. How facebook would shard it users database
- Questions on mulithreading, immutable class, concurrency
Round 5: Design, Previous experience and practical questions
- Explain any 1 project I enjoyed working on
Interviewer was not interested in my project and moved to a design question
- Design a traffic signal starting with all use cases, HLD, LLD
- 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