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My IITD interview was scheduled on 24 May, 2018. I have made up my mind to not join IITB and join IITD(due to location preference). I was setting my foot inside an IIT for the first time in my life. The first shock came when I entered the college gate. I asked the guard where is **** hostel. As I was on foot he started smiling and politely replied beta wo hostel to 2 kilometer door hai. Then I remembered that this is not NIT srinagar(My B tech college). It is one of the most prestigious IITs. How naive of me to underestimate its campus area. While I was thinking all this an auto came from inside the campus. The guard stop that auto and asked him to take me to the hostel. I reached the hostel and told the receptionist that I have come for M tech interview. I was asked to pay Rs800 for two day day boarding and mess facility usage. I was then allotted a room. I met some other candidates and spent the whole day roaming here and there.

On the day of interview first there was a briefing in which Professor Sarangi gave us details about the interview process. Points from the briefing:

  • A candidate has to score at least 7 points out of 10 in the interview to be even considered for M tech programme.
  • A candidate has to score at least 9 points out of 10 in the interview to be considered for MSR programme.
  • Weightage given to GATE score would be 70 percent. 30 percent weightage would be given to interview.
  • Even if only 10 candidates qualify the interview, IITD would proceed with only those 10 candidates. No compromise on quality and no waiting list.

After this we were asked to sit inside a waiting room. My turn came in the very last. I entered the interview room to find 3 people sitting there. I greeted them and they asked me to take a seat. After this the 1st person asked the following questions:

  1. What is quicksort?
  2. Can you find the kth largest element in an array using the approach taken by quicksort?
  3. Write the code for that algorithm?
  4. A rectangular grid was drawn and I have to find the number of paths from one corner to another?
  5. Write code for printing all paths in question 4?
  6. Find the recurrence relation for the recursive solution that I wrote for Question 5?

I was able to answer all questions completely except question 3 where the professor confused me and then I got stuck.

The first professor was satisfied. After this the 2nd professor asked

  1. Give the mathematical proof for If a number is divisible by 3 then the sum of digits must me divisible by 3 ?

I said I don’t know and then he asked the 3rd professor to ask questions?

  1. He explained a processor (which can have infinite number of cores) and then told about a program where the sequential part is 20 percent and rest is parallel. He then asked to find the minimum number of cores required to achieve 10 times speed up?( A tricky one)
  2. My answer to first question made him happy. He made some changes to the above question and asked me to solve the question. I don’t remember that question now. This was the last question of the interview.

Result: selected for M Tech but joined IITB.

posted Aug 31, 2018 in Interview Experience
edited Sep 2, 2018 by


congrats bro...after reading all your interview experiences it looks like post gate preparations r more tougher than the gate xam.
what is the answer for the questions asked by third professor (infinite cores.) ??
The answer to the third prof's question is that it is not possible. The maximum speedup that can be achieved is 5.
how you prepared for such tricky questions
It can be calculated using Amdahl's Law