# OYO Rooms Interview Experience 2018 (On Campus)

Oyo rooms came for campus placement in our college on 17th August.

**Online Round: **It had 20 MCQ and 2 coding question. Total marks was 161.

- First question was based on
**GCD**calculation. - Second question was based on
**BFS Traversal.**

30 students out of a total of 150 were selected for the F2F interview.

**Round 1: **The interviewer was pretty chill, and first made me comfortable. The round begin with usual introduction and then straightaway jumped to DS/Algo questions.

- My first question was the water tapping problem, I hadn’t seen this question. But the interviewer gave little hints and could reach the final solution. He then asked me to code the approach and verified it with few dry runs.
- The second question was to give the lowest common ancestor of Binary Tree. I gave him the recursive O(n) approach and coded it too.

This round lasted around an hour. 21 students were selected for the second round.

**Round 2: **Again I got a friendly interviewer. After introduction I got a very simple question.

- Given cost/kg of items and their quantity. Also given a bag of specific size. Find out the maximum cost that the bag can be filled with.
- It was a this puzzle. I could come up with the answer if we were allowed to fold the rope, which wasn’t allowed.
- Next he asked if I am comfortable with OS and DBMS questions. I said yes. He asked basic concepts of OS like difference between Process and threads, what do you understand by deadlocks, what is semaphore and mutex, etc. I answered all of this.
- Given a binary tree, print sum of all nodes at same vertical level. First of all I tried finding a pattern in nodes at same vertical distance. Then it clicked me that, we can use the concept of horizontal distance like here. He asked me to code it and I did so.
- Given a sorted array, where values occur in pair, except one value. Find that value. I thought that to do better than the naive O(n) solution, we can do something similar to binary search, where we remove one half of the array. Then I saw the odd-even pattern of indexes changing after the non-pair element. I came up with a solution and he asked to code it, which I did.

After this round many students where told ‘no further rounds’. It included people who did extremely well and were selected, and also the one’s who weren’t selected. The rest around 10-12 including me were asked to wait, in case of further round.

**Round 3: **It had only 1 question

Suppose in a social network like FB, where I have a friend, and my further my friends have friends and so on. And each person likes some books.

Q1. Given a person, return the books he likes.

Q2. Return k most liked books in the network.

I was confused wheter I had to design DB for this kind of situation or it was a system design question, or if I had to choose DS for different things. the interviewer clarified ‘I had to code it’.

So I told the various data structures I would use for storing these, like max-heap for book like count, so that I get k most liked books in O(k) once the heap is built. Next he asked me to write code for this approach.

13 students were selected and unfortunately I wasn’t. And I am still interviewing for other companies for my first job! 😛

Tip: OYO Rooms interview are heavilly inclined towards DS/Algo, prepare all the previously asked interview questions specially from Binary Tree and DP.