IIT Madras MS (Computer Science) Interview Experience

This year the cut-off for the MS program at IIT Madras was a GATE score greater than 600 and a UG percentage greater than 75%. They shortlisted 231 candidates for the written test, held on 8th May 2018. Around 160 of the 231 candidates showed up.

The written exam started around 2 p.m. on the same day. There were two papers: an objective paper and a subjective paper.

1. The objective paper had 30 questions, each worth 2 marks, with negative marking of −0.25 for each wrong answer. The syllabus matched GATE. Each subject contributed 3 questions, and the questions were more logical and thought-provoking than GATE — 5–7 were straightforward. The aptitude section had 5 questions and was not easy at all.
2. The subjective paper had 2 questions. The first asked us to build an algorithm to find all local minima in a given complete binary tree. The second was a statement of purpose: “Why do you want to pursue MS at IIT Madras?”

The result was declared around 7:30 p.m. the same day — 54 candidates were selected out of 160 for interviews the next day. With hard work and blessings, my roll number was on the list. I learned a fruitful lesson about the mistakes I’d made in GATE, and about how it all comes down to those three hours to convert your potential into achievement.

The next day we reported at 8 a.m. After document verification, candidates were randomly assigned to one of three panels. My interview started at 2:30 in the afternoon. There were four professors on my panel — very friendly and supportive, encouraging a two-way conversation. One panellist looked at my GATE score and academic record and asked me to elaborate on my machine learning research and internship. They were impressed with my answer to “Why do you want to pursue MS at IITM?” I already knew about two of the professors and the deep-learning lab, as I’d used one of their papers — a plus point for me.

I had to choose one subject from a list. Since I’d interned in machine learning and done research in deep learning, mine turned out to be pure linear algebra, with a binary search tree question at the end.

After a healthy introduction, one professor asked me to pick up a marker and began:

Interviewer 1: Do you know linear algebra well? Me: Yes, sir. Interviewer 1: Suppose a 3×3 matrix is given and two eigenvalues are the same — is it possible their eigenvectors are also the same? Me: Yes, because the basis is the same; we’re just multiplying the eigenvector by a scalar, so the direction stays the same, only the magnitude changes.

Interviewer 1: Construct a 3×3 matrix where two eigenvectors are the same. Me: A good discussion followed, and I finally constructed the matrix.

Another interviewer dictated an upper-triangular matrix and asked me to find the eigenvalues — the three diagonal elements (easy). Maybe they just wanted to see if I could give the right answer under pressure.

This question was interesting:

Interviewer 2: Matrix addition is just adding respective values of two matrices, but why is matrix multiplication so complex? Me: I was amazed — I’d never thought about why multiplication is defined this way; I’d just learned what the book taught. I couldn’t give a clear explanation.

A few more linear-algebra questions followed, leaning towards machine learning.

Interviewer 3: Last question — draw a random binary search tree with five nodes. If I give you any 5 random integers, is it possible to fit them into this structure? Me: Yes. Out of the 5! combinations, one would fit — because the in-order traversal is the sorted sequence.

They seemed satisfied. Before ending, I mentioned my year-long research work and contributions to the AI lab of IIT Madras. All four professors smiled, and the interview ended with five happy smiles.

The interview lasted about half an hour, after which I walked around the lush green campus for a few hours. A memorable experience.

On the evening of 28th May 2018, around 7:15, I randomly checked the IITM website and found my name on the list under the HTRA category. A huge sense of relief — hard work, the blessings of family and God, and luck, all combined, paid off.

To sum up my journey with the famous line: “Why do we fall? So we can learn to pick ourselves up.”

Don’t quit. While there’s life, there’s HOPE.

If you have any doubts about the GATE exam or how to prepare for the interview, feel free to reach out.