M.Tech Admission Interview at IIT Delhi (Computer Technology)

(AIR 422 GATE 2019 CSE)

I had appeared for IIT Delhi M.Tech in Computer Technology admission interview on 15.05.2019.

Computer Technology is a course offered by the Electrical Engineering Department for students from EE/ECE/IT/CSE/IN backgrounds. Students are initially shortlisted for an interview based on GATE score. Then the selection of the student depends on the interview performance. I was asked questions from CSE since that is my background.

This course offers wide variety of subjects like machine learning, systems, software engineering etc. This link can be referred to know about the course details http://ctech.iitd.ac.in/ctech_structure.pdf . Also refer this website for all the informations about its placements, research, faculty etc. http://ctech.iitd.ac.in/index.html .

After initial documents verification I was asked to go in for the interview. 

prof: (Went through my semester marks and other records.)
          What field would you be interested to work in, in the future?

me: Sir I have been studying machine learning concepts, my final year project is also on ML. I would like to continue in this field.

prof: Please go ahead and explain to me your final year project.

Then I explained the whole project idea, my approach. He asked every detail about it, like why did I choose those set of features, why I used those algorithms, what accuracy measure I used and why, scoring and so on...

prof: Explain the support vector machine algorithm...kernel support vector machine algorithm...which kernel did you use...can you give me an overall idea about that.

I used diagrams to explain them, it was simple, he just expected me to explain the intuitions behind it. He also asked me the concept of maximum margin classifier, but all in all simple and clear explanation sufficed.

Then he was about to ask me more about machine learning algorithms, for which I wasn't interview ready, so I made an effort to save the day.....

me: Actually sir, lately I have been largely focusing on my GATE preparation, so I will be more comfortable talking about Algorithm, Databases, Operating Systems.

I did not expect him to be this much cooperative....

prof: Okay then, can we talk about quick sort?

me: Yes sir!

prof: Without taking any examples, derive the average case and worst case time complexity.

me: (Derived them)

prof: Now derive the time complexity when the array is getting divided into sub arrays in different ratio each time.

me: (Derived it)

Now, since I said that worst case time complexity only occurs when the array is sorted or all the elements are the same..... 

prof: Really? Those are the only cases where the worst case occurs?

me: (puzzled)
Then I took many examples and tried to convince him that those are the only cases, but matter only cooled down when I managed to see my mistake, I should have been more specific.

Sir the worst case time complexity occurs in these cases when we always choose the leftmost or the rightmost element as the pivot element.

prof: You sure we get the worst case time complexity only when we set the rule to choose the leftmost or the rightmost element as the pivot?

me: (after thinking for sometime) For the worst case time we need not set any such rule, the array could be one among the two cases (sorted or all the elements being the same) and the pivot selection could be randomized, but if it always chooses the largest(or smallest) element as the pivot, then we will get the O(n^2) time complexity.

prof: So according to you what should be the best way to choose the pivot, for any array, sorted and unsorted both? 

me: We could choose the median of the array in O(n) time and then take it as the pivot.

prof: What if I don't allow that many comparisons. 

me: I can use randomized approach.

prof: But that might also give O(n^2), you just said. Alright I am allowing you just three comparisons.

me: (No idea about that, but still said something) I could take the first, middle and the last element of the remaining array each time and then take the median among those three as the pivot. 

prof: Why do you say so?

me: Since I am allowed only three comparisons, I am choosing just three elements and taking their median, in this manner we are atleast eliminating the possibility of choosing the maximum/minimum every time, even if the chosen element is not the actual median

prof: (With a pause) Alright, we are done here, you can go.

me: (Thinking that this might not be enough) Sir would you like to ask me any questions from Databases or Operating Systems?

prof: It is okay, you can go, I got a feel.

______________________________________________________

After this I left thanking him.

Overall my interview was all about quick sort. Initially I was happy when he uttered the word quick sort, but they can discuss even such easy topics for quite a long time. 

It was a simple interview, I felt that they do not expect us to possess any advanced knowledge, but just want us to try all the problems nicely and to be clear and precise about the answers. If we try well they will even give us plenty of hints and correct some of the mistakes too.

On May 24th I received an email saying that I am selected!!

______________________________________________________

Thanks for your patience!









Comments

Popular posts from this blog

IISc Bangalore CSA M.Tech (by research) Interview and Written Test Experience

Admission to M.Tech(CSE) by coursework/M.Tech by research/MS courses