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# BuyHatke Interview Experience | FTE – Campus Placement

The eligibility to the company was through a CV shortlisting round.

Round 1: The first round was a coding round on Interviewbit.com. It comprised of 4 coding questions only. The questions were fairly simple.

The problems were:

1. Merge a given interval into a list of intervals
2. Find unique quadruples that sum up to a target value.
3. Find all nodes at a distance of k from a given target node
4. Box stacking problem

This was easy and 15 people were selected for further rounds. The problems were being manually checked and

Round 2: This was a skype interview round, which started with a basic discussion on my resume. Where the interviewer asked me questions about my schooling, my internship. Simple questions like where i did my internship from, what did i do in the internship.
Then he started asking me operating system questions

• What is process and thread? What is the difference between the two.
• What do you mean by thrashing?
• What is deadlock and what are the necessary conditions for deadlock?
• What is the way to prevent a deadlock?
• What is priority inversion and what is the solution to it?

Then he asked me questions on data structures and algorithms. The first question was,

1. What is the number of binary search trees that you can make from a given sorted array that consists of only unique numbers. (Catalan number)
2. Given a inorder and preorder of a binary tree, write a code to print the tree, if you can identify a unique tree from it.
3. Write a code to find the next greater number with the same set of digits as that of a given number. eg for 4132 you can make 4213.
4. Given a character ‘c’ and a string ‘s’, find the number of substrings that have the character c present only once in them.

For this round, I was asked to write a running code for all the questions on codeshare, then he would run them on the coding blocks ide to see if I was correct or wrong.

Round 3: This round is called the famous CEO round of BUYHATKE where the CEO Gaurav Dahake himself takes the interview of the candidates.

We were 7 candidates left for the final round, which he was interviewing simultaneously over skyp textual chat. The first question was to design and code a elevator system;

1. . You need to design an efficient elevator system. Think over it. And take test cases.
100 floor building
You are on the 27th floor going to the 100th floor
And person from 60th floor who wants to go downwards
Person on ground floor is pressing to go upwards. Ground floor person has requested first. Whose request would you honour first. According to your algorithm. How would you code this ? What all variables would you take and what would be the complexity of the code?
2. The second question was an extremely vague sort of puzzle.You have a jar filled with water. There’s a lid on the top. You are going out for 7 days. Once you come back you should be able to figure out whether someone opened the jar or not. What sort of mechanism would you build to do that? The jar is a glass jar that is 80% filled, has a lid that can be raised up to open the jar.
I don’t know what was the expected answer to this question, but i gave him many answers. Like using a trap sort of mechanism or a gas immiscible with water, or a one way lock, or pressure sensor or cameras etc. To which after some time he finally said ok.
3. All this while he was on text and then i got a voice call, on which he asked if there is some way in which we could read the messages sent by whatsapp from some other application? To which i was not very sure but i knew we could so i said yes. Then he asked me to think how could we do that and gave me some time to think. I responded within 2 minutes saying i know the answer, but he was busy with someone else’s interview.  He asked me to type out the answer after 20 minutes of waiting. When i started to do so, he asked me if I could send him a sample apk.
Post which i started making the android application, this was something i had never done before but after half an hour of struggle I could manage to complete the task.
4. Imagine you have a dictionary
You need to find the list of all words which are compounds words
moonlight = moon + light
newspaper = news + paper
AFT = a + f + t
the dictionary needs to be traversed and you need to figure out all such words
a
aft
afte
after
aftereffect
afternoon
afterthought
air
airbag
aircraft
airline
bag
c
e
effect
f
plane
r
thought
t
I could solve this question using two approaches and he was satisfied with the answer.
Here are the codes.
https://ideone.com/S3gmxF – using TRIE
https://ideone.com/2a7GKT – using DP
5. All this time i was just typing out stuff because he was interviewing candidates simultaneously. Then he called and it looked like he was reading my code for the first time. He asked me how the code was working. I explained it to him.

The final round lasted 8 hours, from 3 to 11. To be frank, I wish he would have interviewed us one at a time instead of multitasking. Because after 6 hours of interview he asked me to wait for 5 minutes and then i got a response after 48 minutes, and in the response he asked me to again wait for 5 more minutes, to which he responded after 35 minutes. And he asked me my name, which was very shocking. Because we had been interviewing for the past 6 hours.

It was a very tiring experience, finally I got a rejection. I just wish they would have at least let me know of why they rejected me, after such an interview. And i wish it would have been a dedicated one to one interview, so that he could judge us appropriately.