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I received an email on 14th May from the program coordinator at IIT Indore saying that I had been shortlisted for the interview round. My interview was scheduled for 17th May between 2:30 PM to 5:30 PM.

Now, after my GATE results, I was a little heartbroken knowing that I wouldn’t make it to the IITs but I had consoled myself with the hope of getting into something like IIIT Bangalore. When I got the email though, I quickly realized that I was very ill-prepared for any technical interview as I had not studied anything GATE-related after 13th February. So I took a one-day leave from an internship I am doing and started going through GeeksForGeeks and this site to prepare DSA and OS over the weekend.

From OS, I mostly studied deadlocks and I went through some typical competitive coding problems for DSA. Little did I know what was in store for me. 

---

Fast forward to 2:30 PM on 17th May. I wore a shirt and sat down in front of my laptop. The call came at 3:45 PM and the person on the other side informed me that I was going to be sent a Google Meet link and to join it after a second call. The second call came at 4:30 PM.

When I joined, I saw 4 people in the panel. Everyone’s mics and camera were turned off except for the mic of the main interviewer (we’ll call him P1), who I recognized as the admission program coordinator. The two others were professors and the fourth person was the one who called me.

P1: Hi Anirban. Give us a short introduction of yourself.

Me: (Talked about who I am, my current educational background and why I want to pursue research in AI, and what I have done so far)

P1: Okay. Tell me about your B.Tech Project.

[My project is based on using Computer Vision for ad detection. I spoke about it in detail and the interviewer seemed quite interested. For the next 10 minutes, we discussed only this. He asked me for details about how I implemented some things and what error detection measures I had built in. Basically, we had a nice conversation about my project and in the end, he even suggested some ways in which I could make it even better.]

P1 : (gesturing me to the second interviewer). Sir, would you like to ask any questions? (Handed me over to P2)

P2 : So are you familiar with the faculty at IIT Indore?

Me: Yes, sir. I know that (named two of the interviewers on the panel, one of them being P1 himself) have published some incredible research papers in the field of image detection AI. (I also knew that P1 had worked with biometric verification using AI methods, so mentioned that).

P2 : Okay, great. (Handed me back to P1)

P1 : Okay, Anirban. So can I ask you a simple maths question? (I said yes). Okay, so imagine you have a dice and the probability of getting a 1 is p, the probability of getting a 2 is p², and so on. How do we calculate the value of p?

Me : (Answering that it would be a geometric progression equation where p+p²+p³+….=1 and then we can use the sum of GP formula to shorten it. Was about to try to solve it on paper when P1 said….)

P1 : Okay, I think you get the idea. (Told me a method to solve for higher polynomial powers). Do you have any questions for us?

Me : (Asked about what material I should follow to further my knowledge in image processing AI. I mentioned that I already have some personal projects and an internship, and about how I am trying to learn Linear Algebra in-depth from Gilbert Strang’s MIT OCW series and its applications in AI)

P1: (Told me how I must never forget the basics of AI and neural nets, and to solve sums for the Gilbert Strang book to make my Linear Algebra stronger. Finally….) Thank you, Anirban. You may disconnect now.

---

So that was my interview and I got the offer in the first round. My main take-away for those aspiring for a master's in CSE is that the subjects in B.Tech or GATE should not be your end-all-be-all. If you are going for masters for anything other than purely placement reasons, be sure to invest some time pursuing Machine Learning or Competitive Coding or Full-Stack Development, or whatever it is about Computer Science that you’re interested in, during your B.Tech years. Not only would you be better suited for placements if that’s what you wanna go for but it will also greatly help boost your chances in master's interviews and give you a decent head-start in your curriculum ahead.

I prepared for GATE starting from April 2020, without any coaching or even standard books. I learned pretty much everything that I needed to know from Gate Overflow, GeeksforGeeks, Stack Overflow, and free RBR lectures. Now would I have secured a better rank with formal coaching? Maybe. But I didn’t want to be spoon-fed stuff in a classroom to learn something that I knew I could learn by myself for a fraction of the cost and at my own pace. All told, my total investment behind GATE is about Rs. 2000. 1500 for MadeEasy + AceAcademy test series and 500 for a 30-years GATE question bank from Amazon.

Greetings to all, I am Animesh. I have appeared in GATE 2021 and my gate score was 742 with a rank of 447 General Cat. Here I am posting various questions asked from me in different interviews for MS/M.Tech Research courses.

Note: My interest lies in Machine Learning and AI, that’s why I prepared Linear algebra along with basics of ML for these interviews.

1. IISC Quantum Technology M.Tech interview questions : https://docs.google.com/document/d/1E9Ta_1zm8nvktaWcKOchMDTh3BWQ-kf2KGilubRlpJc/edit?usp=sharing [This was a new course started by IISC this year(2021), and I had no prior experience in this Quantum Tech field, so I appeared in this interview just for the sake of experience]
2. IIT Bombay MS TA interview questions : https://docs.google.com/document/d/15A4SsQsc5diSsP6gxR73joAY8yUo6mVGXcYHk6Yy-nQ/edit?usp=sharing
3. IIT Madras MS interview questions : https://docs.google.com/document/d/1jDsTDYyz7khijZr30PvOmdEup7a5cDy-EW1QYVIYzT4/edit?usp=sharing

I will be adding few other interview experiences(IISC CDS, IIT Bombay MS RAP etc) soon.

Some memory based questions:

1. Time complexity to find the maximum element in the min heap and explain the method?
2. Given an array of length $n$ and a number $x$ find out two such elements in the array such that their sum is equal to the number $x.$
3. Given an array of length $n,$ find two numbers such that their sum is equal to the rest of $n-2$ elements if there exist such case?
4. Two linked lists are given and due to programming error end node of first linked list is now pointing to some node of second linked list, how will you find that node? and you don't know which one is $1^{\text{st}}$ linked list and which one is $2^{\text{nd}}.$ The data values are not distinct.
5. Define joint probability in terms of conditional probability?
6. How will you find a cycle in a directed graph? some questions on forward edge and back edge.
7. Sort an array of $n$ elements with k distinct elements optimally. How will you find the distinct elements in the array optimally
8. A $n\ast n$ matrix is given such that $A_{ij} = A_{ji},$ what will be the rank of this matrix?
9. How many different values a random variable can take with zero variance and why?
10. Prove that a directed acyclic graph has atleast one vertex with zero indegree.
11. Various ways to solve subset sum . Variations of the same problem.
12. Algorithm to get maximally connected graph having two components.
13. Suppose we have $A\ast B.$ If we know determinant of $A$ is $1.$ What can we tell about Rank of $A\ast B$ in terms of $B.$
14. Give $O(k\log k)$ algorithm for finding $k$ minimum element.
15. Prove two vertices of a graph have same degree.

Bharati Padhy, $\text{Gate}\; 2020, \text{GS-}624, \text{AIR-}1531, \text{Jest}\; (2020)\; \text{AIR-}75$

Some memory based questions:

1. Yourself
2. Write a program to find the $2^\text{nd}$ minimum number from an array in one pass.
3. CMMI Levels
4. Difference between Production environment and Deployment Environment.
5. You have given some ingredients and you have to make a recipe out of it. Using graph theory terms explain this scenario how you will do it.
6. If a matrix is invertible then what can you say about it. How to take inverse of a matrix

Bharati Padhy, $\text{Gate}\; 2020, \text{GS-}624, \text{AIR-}1531, \text{Jest}\; (2020)\; \text{AIR-}75$

Some memory based questions:

1. Yourself
2. Why Data Science?
3. If you have n numbers how many bits are required to present that numbers?
4. If you have a matrix of $3\times 3$ which is not invertible then what you will say about the Rank of that matrix.
5. How many probability distribution function are there which you know?
6. Explain Binomial distribution? Mean and variance?
7. In which distribution Mean and variance are same?
8. You have given a number; you have to find the number of digits which are divisible by $3.$ Eg. If number is $123$ then it should return $1$ as output as only $3$ is divisible by $3.$
9. What is the complexity to find a number from BST.
10. You have a bidirectional graph max number of edges in that graph?
11. You have $2$ events $A$ and $B. P(A)=0.6, P(B)=0.7$ what you can say about it disjoint event or dependent? Axioms of probability.
12. There is a person $A,$ who has $2$ kids. If the first child is girl then what is the probability that $2^{\text{nd}}$ child is also girl.

Bharati Padhy, $\text{Gate}\; 2020, \text{GS-}624, \text{AIR-}1531, \text{Jest}\; (2020)\; \text{AIR-}75$

Some memory based questions:

1. How many Prime numbers are there in universe?
2. How will you prove that there are infinite prime numbers?
3. You have given an empty stack which can hold atmost $3$ elements, what will be the top of stack after following operations: Push $6,$ Push $4,$ Push $1,$ Push $5,$ Pop, Pop

4. n=10
   Fun(n)
   { 
       while(n>0)
       { 
           printf(n);
           Fun(n-1); 
       }
   }
   

5. How many maximum regions will be there when we draw $19$ lines on the plane?

6. You have a binary tree with $n_{1}$ vertices of degree $1, n_{2}$ vertices of degree $2, n_{3}$ vertices of degree $3.$ Explain $n_{3}$ in terms of $n_{1}$ or $n_{2}.$

7. do {
   sum=0,i=0;
   i++;
   sum+=i;
   }
   while(i<5)
   printf(sum);

Prof - Hello , Please introduce yourself .

Me - Introduced .

Prof - Given an array can you write code to find minimum and maximum of array .

Me - Yes Sir

Here is the code I had written -
int max=arr[0];
int min=arr[0];
for(int i=1;i<n;i++)
{
   if(a[i]<min)
      min=a[i];
   else if(a[i]>max)
      max=a[i];
}

Prof- Can you optimisze this code So that number of comparisons are reduced ?
Me - I started explaining Tournament Approach . In which total number of comparisons to
find minimum and maximum elements of array is (3n/2 -2) .

But the way I explained was
not very clear to interviewer . They kept asking me how you are approaching it . I told them
to divide the array into two parts of size n/2 then form min and max array . And then take maximum
from max and minimum from min . This part confused interviewers and the whole interview almost
revolved around this topic .
 
Prof - Can you write code to construct a node for Binary search tree .
Me - written .
There were some minor  mistakes I was doing while writing the code they pointed out and ask me to correct.

I used malloc in my code to which one professor asked

Prof- Why malloc is used ? What does this function do here.
Me- To allocate memory in heap for variables .

Prof - What does calloc function do ?
Me - It provides contigous memory in heap just like an array .

Prof- In this code can we use calloc instead of malloc ?
Me - Yes sir we can . (explained)

Prof - Now insert some nodes inside this BST . Explain algorithm only .
Me - Explained

Prof - Whenever you will insert any node do you have to change or update any internal nodes pointers.
of this BST ?
Me - No sir , Because this is a Binary search tree which is not required to be balanced . So each
time a node is inserted as a leaf node . So no need to update or change any internal nodes . If tree was
suppose AVL then updation is required .
 
I don't think my min-max approach was clear to them . Because even in last they were discussing about it . Professor asked me that are u doing pair-wise comparison and I said No in hurry .
After some instant one professor said that he is explaining same thing .

Prof - Okay , your interview is over now . Do you want to ask anything ?
Me - No sir.

Prof - It was nice to talk to you . We will announce results in next week. all the best.

Interview duration was around 30 minutes . Although I did some
mistakes as I was in pressure . But was very nice experience

Bharati Padhy, $\text{Gate}\; 2020, \text{GS-}624, \text{AIR-}1531, \text{Jest}\; (2020)\; \text{AIR-}75$

Some memory based questions:

1. $R_{1}$ and $R_{2}$ are equivalence relation then which of the following is true?

1. $R_{1} \cup R_{2}$ is equivalence
2. $R_{1} \cap R_{2}$ is not equivalence
3. $R_{1} \cap R_{2}$ is not transitive
4. None of the above

2. $C(n,k)$ means choosing $k$ numbers from $n$ numbers. Write the recurrence relation for this:

1. $C(n,k) = C(n-1,k-1) + C(n-1,k)$
2. $C(n,k) = C(n-1,k-1) + C(n-1,k)$
3. $C(n,k) = C(n-1.k) + C(n,k-1)$
4. $C(n,k) = C(n,k-1) + C(n-1,k)$

3. $N\times N$ grid which has $n^2$ cells, you have to travel from bottom left corner to the top right corner. You can take only up and right path. How many such path possible?

1. $(2n)!/n! n!$
2. $n^2$
3. $C(2n,n)$
4. $n(n-1)/2$

4. There are n guests in a party. Each and every person in the party will handshake with each other exactly once. How many distinct handshakes possible. Recurrence relation?

1. $T(n) = T(n-1) +1$
2. $T(n) = 2T(n-1)$
3. $T(n) = T(n-1) + T(n-2)$
4. $T(n) = T(n-1) + n-1$

5. Number of relations which are reflexive and symmetric both.

1. $2^C(n,2)$
2. $2^P(n,2)$
3. $2^((n^2+n)/2)$
4. $2^n$

6. 

while(1) {
    int *I = (int *) malloc (sizeof(int));
} 
printf(“Hello world”);

1. Hello world
2. Segmentation fault
3. Infinite loop
4. Stack overflow

7. There is a polynomial time function which calls constant times some other functions which also take polynomial time what is the total complexity?

1. Polynomial
2. Exponential
3. Super exponential
4. None

8. NP problem is best known as

1. It is decidable in polynomial time
2. It is verifiable in polynomial time
3. It have an algorithm of exponential time
4. It does not have any algorithm

9. There is a polynomial with highest degree $2.$

 $\begin{array}{c c c c c} X & 1 & 2 & 3 & 4 \\ F(X) & 3 & ? & 13 & 21 \end{array}$

 Find value of $f(2)$

1. ____
2. $25/3$
3. ____
4. None

10. Find the remainder of $7^{222} \mod 11$

1. $7$
2. $5$
3. $2$
4. $0$

11. What is the size of page table if CPU generates $32$ bit address, page size is $4$ KB and PTE size is $4$ Byte.

1. $8$ MB
2. $2$ MB
3. $4$ MB
4. ____

12. You have $m$ resources $,n$ process competing for them each having $j$ number of resources requirement(consider all $m,n$ and $j$ are positive). Find the proper inequality which MUST ensure freedom from deadlock

1. $M=n+j+1$
2. $(m-1)>= n(j-1)$
3. ____
4. ____

13. Which of the following is/are true

1. $\text{L1}$ cache is generally faster than $\text{L2}$ cache
2. $\text{L1}$ cache is generally smaller than $\text{L2}$ cache
3. $\text{L2}$ is generally faster than middleware
4. RAM is faster than $\text{L1}$ cache

14.Which of the following is/are false

1. Preemptive schedule means longer delay for the shorter processes.
2. Round robin scheduling follows FIFO
3. In SJF we need prior knowledge of process running time
4. SRTF is a non-preemptive version of SJF

15.Which of the following is/are true

1. There is no polynomial time algorithm to find the graph is Euler is not
2. There is a polynomial time algorithm to find the graph is Hamiltonian
3. Dijsktra’s all pair shortest path algorithm will not work properly when there is a negative edge.
4. None of the above

Bharati Padhy, $\text{Gate}\; 2020, \text{GS-}624, \text{AIR-}1531, \text{Jest}\; (2020)\; \text{AIR-}75$

Some memory based questions:

1. Brief intro
2. DSA which area?
3. Define complete binary tree?
4. Heap data structure explain?
5. In heap sort - how many times you do build heap?
6. Heapify - with complexity?
7. Build heap complexity?
8. Definition of graph and tree?
9. Definition of forest?
10. Minimum number of trees require to make a forest?
11. Difference between malloc and calloc?
12. Null and void in C, can we compare them?
13. In an array complexity to find an element which is neither min nor maximum?
14. Complexity to find $2$ such elements which are neither min or max.
15. Complexity to find a min element from an array.
16. Applications of stack?
17. Recurrence relation of linear search, Merge sort, Binary search with complexities.
18. Explain $\Theta(n)$ in merge sort?
19. Prove $\cos^2\theta+\sin^2\theta=1$
20. Qsn on pigeon hole principal
21. What is conditional probability?
22. Bayes theorem?

We were shortlisted for the interview based on GATE score. There was no written test. The interviews were conducted on the 24th and 25th of May. There was a presentation before this where the HoD of the CSE department at IIT Madras explained everything about the MS and PhD programs and patiently fielded questions for about an hour.

They called me on my phone while the interview of the person before me was going on and told me to be ready. I joined in 10 minutes when they called again.

There was a panel of 6 professors out of which 3 interacted with me. The first professor asked for my introduction as is standard. The second professor shared a Codeshare link with me and began my interview. The question: write a function to find the top 3 (maximums) of a large array. The array is not pre-sorted and sorting is not allowed.

I asked if any time complexity requirements had to be heeded, and the prof asked me to go ahead and write a simple function. I wrote three loops, each to find the first, second and third maximums of the array. He expected me to have done it one loop, and started saying that I had a bug in my code, but then noticed the 3 loops and went “Oh. You’ve written three”.

He then asked me to do it in one loop. I thought for a bit and he gave me a hint: find the top 3 amongst the first 3 elements of the array and carry it on across the array. After a bit of light discussion, I wrote the right code.

After this, the third professor unmuted himself and entered the discussion. He asked me about my choice of linear algebra and I mentioned that I had selected graph mining as my research topic, which was under intelligent systems, so prepared linear algebra as the area needs it as a basic subject.

P: What topics do you know in linear algebra?
Me: Elimination, rank, subspaces of a matrix, vector spaces and subspaces, determinants, eigenvalues and eigenvectors…

(Unlike my IIT Bombay interview, this time I had come prepared)

P: Let's start with vector spaces. What is a vector space? What is a subspace?

Me: Defined both of them, explained their properties.

P: Is the zero vector part of a vector space?

We had a bit of back and forth on this, and then he asked me that since I mentioned that a vector space is described by the span of its basis, I could make the scalars $0$ and would get the zero vector, to which I said yes.

He mentioned how vector spaces have other properties and I suddenly remembered – mentioned distributivity, associativity, and he said yes.

P: Suppose we have a matrix equation $Ax = b$. $x$ is a column vector, $b$ is their product. What can you tell me about this?
Me: (reciting Gilbert Strang in my head) $Ax = b$ is solvable only when $b$ is in the column space of $A$.

P: Very good. So let’s suppose $b$ is not in the column space of $A$. We now want to solve an equation $A\hat{x} = p$ since $b$ is not there. We want to find a vector that approximately satisfies the requirement. What can you tell me about this situation? Is there a way?

Me: Explained about the concept of projections and derived the equations in chat.

P: Asked a bit more about this, and then asked – how do we know that $A^TA\hat{x} = A^Tb$ is solvable? How do we know the new vector is in the column space of $A$?

Me: Explained about how $b \ – A^T\hat{x}$ or something is in the nullspace of $A^T$ but muddled up what he was asking.

P: Gives a few more hints, asks what the null space of $A^TA$ is.

Me: It’s the same as that of $A$. But I wasn’t sure how that helped.

P: After a while, asked me to check about this offline. Moved to the next topic. Asked whether I can prove that the two nullspaces are equal.

Me: Provided a full proof based on both nullspaces being subsets of each other, which proves that they're equal. He gave me a small hint here too.

P: Wanted to wrap up in interest of time but said “I'll ask you one more question”. Gave me a scenario where we have a large matrix whose eigenvalues we calculated. You give this matrix to a friend and he returns it to you with $1$ added to all the diagonal entries. Will you recalculate all the eigenvalues of the new matrix or is there some other way?

Me: Clarified what he was asking. Then mentioned that recalculation isn't needed. If you add $1$ to the diagonal, it's as if you did $A + I$ where $I$ is identity. And in that case, the eigenvalues increase by $1$.

P: Can you prove this?

Me: Let $Ax = \lambda.x$. Now $(A + I)x = Ax + Ix = Ax + x = \lambda.x + x = (\lambda + 1).x$.

P: Was satisfied.

I thanked everyone and the interview ended here. Around 45 minutes in total (according to the time they called me to join).

We took a 3-hour test on May 2 which was conducted via remote proctoring. The test had 2 subjects extra besides the GATE syllabus – computer graphics and AI. The results were posted on IITB CSE dept’s portal the next day and while theory and computing systems got lesser than the max possible intake, intelligent systems received a lot of applications and they decided to shortlist more candidates in IS than their earlier limit, probably to make up for lesser candidates in the other two categories.

I was shortlisted for RAP and TA. My first interview was with the Cryo-electron microscopy project on May 10, and it was a disaster.

RAP

Prof Ajit took the interview. He asked me to give an introduction, what I’d been doing for the past few years after graduation, why I had selected the CEM project (I could not give a good answer), and then finally asked me a linear regression problem. At this point, I had covered only 15 lectures of Gilbert Strang’s LA course, and while I knew about least squares and projection, I could not give the satisfactory ML-style answer that he was looking for. In 10 mins it was over.

TA

Profs PB and PC took this interview on May 11. Nothing could have prepared me for it.

PC took my introduction, and then PB decided to start. They had actually read my SOP, or had it open at that moment, and asked me about my interest in graph mining. He then said let’s start with graphs (I had prepared basic LA and probability), and I knew I was a goner.

PB: What are Euler and Hamiltonian graphs?
Me: Answered

PB: Which problem is the harder of the two?

Me: Explained that Euler circuits can be checked by checking the degrees of the nodes in the graph. Hamiltonian was a known hard problem.

PB: Explain formally what you mean by “hard”.

Me: Tried to explain the concept of reductions but I could not remember the correct direction of the reduction (from or to known NP complete problems).

PB: Asked the time complexity of the reduction.

Me: Could not answer this one.

PB: Said that I should know the correct direction of the reduction, and that many get it wrong. Then decided to ask probability. Asked about the basic axioms of probability and what Bayes’ rule is and what it means.

Me: Explained these.

PB: Asked me about Naive Bayes classifiers and framed a Bayesian problem (“patient has blood vitals, you can consider them probabilities – we want to find whether he has cancer. How will you frame the equation”)

Me: Couldn’t do it because I had no idea how to write naive Bayes stuff.

I can’t remember what else PB asked me, but right after that, he said he was done in an authoritative tone (if he had been any more authoritative, I would probably have exited my own house chup chaap, forget about leaving the meeting).

PC started asking about linear algebra. I felt like I still had a chance.

PC: Asked about what orthonormal vectors are.

Me: Explained.

PC: Asked what the main property of an orthogonal matrix is.

Me: Got stumped. It’s $Q^{-1} = Q^T$. He then showed it through row-column dot product of the vectors during matrix multiplication. Safe to say I no longer felt like I had a chance.

PC: Shifted discussion to eigenvalues and eigenvectors. Asked me about what they are.

Me: Explained, although not straight to the point (should have just talked about $Ax = \lambda.x$ instead of saying $x$ is a vector in the nullspace of $A – \lambda.I$).

PC: Asked about geometrical interpretation.

Me: Explained about how it produces a new vector parallel to the earlier one. He said “scaled up/down versions of it” and I agreed.

PC: Asked me about eigenvalues of the inverse of the matrix. Asked me to prove my answer.

Me: Gladly proved how they are $1/\lambda$. Probably the only topic I got right in full.

PC: Asks what happens if the magnitude of eigenvalues is less than 1 and they are repeatedly multiplied with the vector.

Me: Obviously the term vanishes as we approach infinity. (this was probably about the diagonal equation and powers of a matrix – I should have said that n independent eigenvectors are required).

PC: Suddenly starts joking about whether I have lost touch with CS after so many years.

Me: I didn’t even know what to say to that.

Suddenly he stopped the teasing (it looked like he saw something on the screen) and asked whether my GATE score was of 2021. I said yes. He was serious for a few moments.

Then he starts joking around again that I should be careful with my answers. Asks me what programming languages I have worked in – I said python and JS.

PC: What kind of languages are these?

Me: At this point I was nervous enough that I said typeless – but quickly corrected to dynamically typed and interpreted.

PC: Is type checking done in Python and JS, as opposed to a language like Java?
Me: Tried to explain that Java is a compiled and bytecode-interpreted language and during compilation, it has a semantic analysis phase where types are checked. But Python/JS wouldn’t have that. Maybe the CPython interpreter would but not at the Python level.

PC: Tried to trick me on this, asked which is faster.

Me: Mistakenly ended up saying that the interpreted ones are faster – yep, an experienced guy saying this.

He had a big smile and told me to be careful before answering.

At this point they stopped the interview and I thanked them and exit. Took roughly 30 mins.

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https://gatecse.in/best-video-lectures-for-gate-cse/

Those preparing for GATE CSE 2022 can join our Telegram group: https://docs.google.com/document/d/e/2PACX-1vQSakC92NFVsZ00iovz6LMlCMW2uJmzVwskfm1WO6UV8anuqcmepblyNfaxZmWesGI6rgR5iRcMGgCa/pub

On 14th May in the evening I received the email for MS CSE interview which was scheduled on 17th May ( I just had 2 days to brush up my concepts and to finalise my fav subjects ! I stopped studying on a daily basis after my GATE exam in Feb :/ - I would recommend every candidate to stay in touch with their subjects ( if they are applying for MS ) as it will help a lot in their interviews )

At 3:30 PM on 17th May 2021 I got a call from IITI CSE to join the meeting via Google Meet. I entered the meeting :-

There were total 6 members present in the meeting ( their videos were off and they all were muted) and three professors questioned me in the interview - I would name them as P1, P2 and P3 ( I don’t know whether the other 3 members were professors or not … I didn’t even looked at their names for once, as I was already a bit nervous because it was my first interview )

P1 - Hi Priyanshu ! What are your favourite subjects ?
( I thought they would ask me for a introduction but they didn’t ... LOL :P )
Me - Sir Linear Algebra, Theory of Computation and Data Structures

P1 - Okay … Linear Algebra ( he seemed interested in it )
What are Eigen values and vectors ?
Me - Answered ( Gave both Geometric and Numerical Intuition )

P1 - How do we evaluate Eigen values ?
Me - Answered

P1 - What are the applications of Eigen values ? and later he asked the same about Eigen vectors !
Me - Answered

P1 - Then he asked me something regarding a matrix relation !
Me - I said I’m not sure about this and later on he simplified that problem and asked me again, then I was able to answer him ( I don’t remember that question exactly)

P1 - Do you know what is a Null Space and what can you say about it's dimensions ?
Me - Answered completely both Null Space and Column Space
( As I wanted someone to ask this :P )

P1 - What is a vector space ?
Me - Answered

P1 - Do the dimensions of column space and row space is same ?
Me - Answered ( even before he completed his question :P )
P1 - Prove it !
Me - Gave him some relations and he seemed satisfied !

P1 - What do you know about Matrix Norm
( I didn’t even heard this term before :/ )
Me - Sorry Sir !

P1 - What is a diagonalizable matrix ?
Me - Answered

{ He asked P2 to ask questions }
( and I thought that the interview was over :P ) – I couldn't hear him properly :/

P2 - So are you working right now ?
Me - No Sir, currently I am in my final year

P2 - Okay Priyanshu your favourite subject is Algorithms ... Right ?
Me - I repeated [ Sir Linear Algebra, Theory of Computation and Data Structures ]

P2 - Define me what is a algorithm in less than 5 words !
( He just wanted a short and precise definition I guess )
Me - Answered

P2 - Have you studied Computer Architecture ?
Me - ( I didn’t even saw my COA notes after my GATE exam )
But still I said -> Yes Sir !

P2 - What are the components of a CPU ?
Me - It was such a silly question but I panicked and said sorry sir :/

P2 - He repeated the question ( as he figured out that I panicked )
Me - Then I said Sir ALU, CU … He stopped me after ALU and CU

P2 - So every algorithm in general has two parts just tell me which part is handled by ALU and which part is handled by CU ?
Me - Answered one part correctly and later on he gave me a hint and I answered the other one as well !

P2 - Let’s talk about Complexity ... Why do we compute it in the very first place … What’s the need ?
Me - Answered

P2 - Let us talk about Complexity Classes !
( He asked me 2-3 questions related to NP class and other undecidable problems - I do got stuck in a question but he gave me a hint and then we were good :P )

[ He passed it to P3 ]

P3 - Priyanshu have you studied Computer Networks ?
[ Worst nightmare - I left CN for my GATE 2021 and I knew almost nothing that I can showcase in my interview and I didn't wanted to mess things up ! ]
Me - No Sir !

( P3 asked me whether it was in my CSE curriculum or not ? Then I answered that the semester in which CN was included got revoked completely due to covid last year ! )

P3 - Tell me what are planar graph ?
( I couldn't get enough time to revise graph theory in those 2 days ) – Drawbacks of not being in touch :/
I was able to recall a planar graph (figure) but just couldn't recall it's property specifically !
Me - Sorry Sir !

Then P2 said in between - Arree ... tell us what is a graph yrr ?
Me - Answered

P3 - How do we store them ?
Me - Answered

P3 - Which one is efficient ?
Me - ( Answered - both for dense graph and as well as for sparse graph )

P3 - Okay Priyanshu you can leave now !

No questions were asked from Theory of Computation ( not even a single question ) and what's worst - P3 wanted to ask some questions from CN (which I didn't even prepared for GATE 2021). Interviews will not go according to your prep/plan all the way long ( So, do revise those subjects which are related to your fav subjects ) You need to adapt to the situations and give your best ! As that's the only thing that you can do ;) And kindly be in touch with your subjects on a regular basis as I mentioned earlier - That will always help !

Take your time to answer your questions, don't be in a hurry !
The professors are quite friendly and they will help you out if you're stuck -
by modifying the problem or by giving some hints !
So, just keep your calm and give your best ;)

Verdict :- SELECTED

Firstly, there was an online written test on 11th May 2021. The test was in 2 parts:

Part 1:

In 1st part, there were 30 MCQ questions each with 1 mark and a penalty of -1 for each incorrect answer. The MCQs were of mostly GATE level. The majority of topics covered were DSA, Discrete Maths, Probability. Few questions were form CO, OS, CN and TOC (1-2 questions each).

Part 2: (Not used for evaluation and shortlisting, only for interview purpose)

Three subjective questions were there:

1) Let us assume, you are the head of Google and decide to build the next version of Google Meet. What features will you use/improve? How can you leverage skills from 3-4 CS subjects to improve the product?

2) There are 100 rooms in a hotel. The hotel manager is lazy. When a customer requests a room, the manager picks a room from 1 to 100 uniformly at random without even bothering to check whether it is already occupied. If the room is already occupied, the customer is asked to leave the hotel. Otherwise, they can check-in. Suppose that 100 customers try to check in, one by one, to the hotel. Show that the expected number of occupants is at least 50.

 

3)

 

I was shortlisted for the interviews. My slot was on 14th May 2021, at 10:30 am.

There were 3-panel members. But only two of them asked questions. I will address them as I1 and I2.

So the interview goes like this:

I1: Please give a brief introduction about yourself.

Me: Given.

I1: From which subjects you want us to ask questions?

Me: Linear Algebra, Probability, Data Structures.

I2: Ok Subham, let's start with the basics. What is eigenvalues and eigenvectors?

Me: Told with geometric intuition.

I2: Ok. Suppose you are given a diagonal matrix, what can you tell about the eigenvalues?

Me: The diagonal elements are the eigenvalues of the matrix.

I2: Prove it.

Me: Told an intuitive proof by the concept that the determinant of the matrix = product of eigenvalues.

I2: Ok. Now, lets move to probability. What are disjoint events?

Me: Told.

I2: Let's suppose you are given a probability of two events A and B. P(A) = 0.9 and P(B) = 0.9. Can you say that these events are disjoint events?

Me: Couldn’t answer. [The easiest question of the whole interview :)  ]. Due to panic, I couldn’t answer.

I2: Ok. Let's now move back to Linear Algebra. Suppose you are given 3 vectors of 2 dimensions. Is it possible that they are linearly independent?

Me: Explained with the rank concept.

I2: Referring to I1, would you like to ask any questions?

I1: Ya sure. So Subham, given a Binary tree, how can you find the height of the tree?

Me: Explained with recursion.

I1: What is the time complexity?

Me: Told.

I1: Ok we are done. You can leave the meeting.

Me: Thank you, sir.

 

They asked subjective test questions from some students. But they didn’t asked me.

VERDICT : SELECTED

 

Tips for future aspirants:

• Don’t panic, they will give you enough time to think, just think freely.
• Be sure you are good with each and every aspect of the subjects you are mentioning.
• For written tests, keep in touch and keep revising your GATE subjects after the GATE exam also.

BEST OF LUCK…

The schedule followed by GATE Overflow for GATECSE 2022

GATE Overflow Test Series for GATE 2022

Schedule of Tests

Advantages of following this schedule:

1. It is not the only good schedule possible but is one schedule where subject dependencies are met 
2. Schedule organized into 4 modules:
   1. First 6 weeks covering aptitude and discrete mathematics fundamentals – most important
   2. Next 6 weeks covering a bit of hardware, programming and computer architecture – builds a good system level knowledge
   3. Next 6 weeks covering more theoretical subjects, probability and OS – building the base of Intelligent Systems
   4. Final 6 weeks to finish DBMS, Operating Systems, Computer Networks and Compiler Design 
3. This schedule is tied to GATE Overflow Test series – subject tests will be added as per the schedule
4. Preparation materials including reference links are provided on GO classroom (free for everyone) as per the schedule – to access GO classroom just create a new account on the home page of it and subscribe manually to each course
5. Even if you are joining late, you can adjust your schedule accordingly - most assignments in GO classroom will allow late submissions and this schedule will be over by November end.
6. Extra points to be followed will be updated here.
7. GATE CSE Subject page should be used for the subject resources (will be updated as per schedule) and GO classroom has assignments in extra. 

---

June 1-6

• Verbal Ability: Finding appropriate word, reading passages, basic grammar usage
• Webpage for Verbal Ability
• http://classroom.gateoverflow.in/course/view.php?id=16
• Must complete all Verbal Ability questions from GO Book
• Logical Reasoning and Data Interpretation: Verbal reasoning ­ deriving conclusion from passage, conclusions as in puzzles (can be in mathematical logic also)
• Exam Link: https://gateoverflow.in/exam/266/go-2022-verbal-ability-1

June 7-13

Quantitative Aptitude: Ratios, speed­-time, directions, work­-time, clock, other numericals, deriving conclusion from graphs, pie/bar charts, sequence and series etc.

• Webpage for Numerical Ability
• http://classroom.gateoverflow.in/course/view.php?id=15
• Must complete all Numerical Ability questions from GO Book, difficult ones to be marked for periodic revision
• Exam Link: https://gateoverflow.in/exam/267/go-2022-quantitative-aptitude-1

June 14-20

Discrete Mathematics: Set Theory & Algebra: Sets; Relations; Functions; Mathematical Logic: Propositional Logic; First Order Logic.

• http://classroom.gateoverflow.in/course/view.php?id=9
• Webpage for Set Theory & Algebra
• Webpage for Mathematical Logic
• You should understand sets, and then move on to Mathematical Logic and come back to do Relations and Functions though if you already know the basics you can do in any order.
• Must complete all GO book questions including TIFR ones, and descriptive GATE questions which will be challenging.
• Exam Link: https://gateoverflow.in/exam/268/go-2022-discrete-mathematics-1

June 21-27

Discrete Mathematics: Combinatorics; Counting; generating functions; 

• http://classroom.gateoverflow.in/course/view.php?id=9
• Webpage for Combinatory
• Must understand all types of balls in bins problem and how to reduce different problem types to them
• GO book questions are sufficient but you must try solving without referring solution
• Exam Link: https://gateoverflow.in/exam/269/go-2022-discrete-mathematics-2

June 28-July 4

Discrete Mathematics: Combinatorics;  recurrence relations.

• http://classroom.gateoverflow.in/course/view.php?id=9
• Webpage for Combinatory
• How to form recurrence relations given a new problem

Discrete Mathematics: Set Theory & Algebra: Groups; Partial Orders; Lattice.

• Webpage for Set Theory & Algebra
• By now must have completed all Set Theory and Combinatorics questions from GO Book.
• Exam Link: https://gateoverflow.in/exam/270/go-2022-discrete-mathematics-3

July 5-11 

Revision, Taking Tests. 

• If you are scoring below 50% you must seriously evaluate your preparation. 75% or above is good going.
• Exam Link: https://gateoverflow.in/exam/271/go-2022-mix-subjects-1

---

July 12-18 

Digital Logic: Boolean algebra. Combinational circuits. Minimization. Number representations and computer arithmetic (fixed and floating point), Sequential circuits. 

• http://classroom.gateoverflow.in/course/view.php?id=8
• Webpage for Digital Logic
• Exam Link: https://gateoverflow.in/exam/272/go-2022-digital-logic-1

July 19 - July 25

Programming and Data Structures: Programming in C. Recursion. 

• http://classroom.gateoverflow.in/course/view.php?id=14
• Webpage for Programming
• Exam Link: https://gateoverflow.in/exam/273/go-2022-programming-1

July 26 – August 1

Computer Organization and Architecture: Machine instructions and addressing modes, ALU, data‐path and control unit, Instruction pipelining, Memory hierarchy: Cache and main memory, Secondary storage, I/O interface (Interrupt and DMA mode).

• Webpage for CO & Architecture
• http://classroom.gateoverflow.in/course/view.php?id=3
• Exam Link: https://gateoverflow.in/exam/274/go-2022-computer-organization-and-architecture-1

August 2-8

Programming and Data Structures: Arrays, stacks, queues, linked lists, trees, binary search trees, binary heaps, graphs.

• http://classroom.gateoverflow.in/course/view.php?id=14
• Webpage for Programming
• Webpage for Data Structures
• Must complete the GO classroom assignments
• Exam Link: https://gateoverflow.in/exam/275/go-2022-data-structures-1

August 9-15

Algorithms: Asymptotic worst case time and space complexity. Searching, sorting, hashing. Algorithm design techniques: greedy, dynamic programming and divide‐and‐conquer.

• Webpage for Algorithms
• http://classroom.gateoverflow.in/course/view.php?id=2
• Exam Link: https://gateoverflow.in/exam/276/go-2022-algorithms-1

August 16-22

Who do not like a break?

No exam 

August 23-29

Revision, Taking Tests.

Exam Link: https://gateoverflow.in/exam/277/go-2022-mix-subjects-2

---

August 30 - September 5

Algorithms: Graph search, minimum spanning trees, shortest paths.

• Webpage for Algorithms
• http://classroom.gateoverflow.in/course/view.php?id=2
• Exam Link: https://gateoverflow.in/exam/278/go-2022-algorithms-2

September 6-12

• Discrete Mathematics: Graph Theory: Connectivity; Matching, Colouring.
• Webpage for Graph Theory
• http://classroom.gateoverflow.in/course/view.php?id=9
• Exam Link: https://gateoverflow.in/exam/279/go-2022-discrete-mathematics-4

September 13-19

Probability: Random variables. Uniform, normal, exponential, poisson and binomial distributions. Mean, median, mode and standard deviation. Conditional probability and Bayes theorem.

• Webpage for Probability
• http://classroom.gateoverflow.in/course/view.php?id=12
• Gravner notes given in GO classroom are mostly sufficient – has plenty of problems too. 
• Exam Link: https://gateoverflow.in/exam/280/go-2022-probability-1

September 20-26

Theory of Computation: Regular expressions and finite automata. Context-free grammars and push-down automata. Regular and context-free languages, pumping lemma. Turing machines and undecidability. 

• Webpage for Theory of Computation
• http://classroom.gateoverflow.in/course/view.php?id=6
• Exam Link: https://gateoverflow.in/exam/281/go-2022-theory-of-computation-1

September 27 – October 3

Databases: ER‐model. Relational model: relational algebra, tuple calculus, SQL. Integrity constraints, normal forms. File organization, indexing (e.g., B and B+ trees). Transactions and concurrency control.

• Webpage for Databases
•  http://classroom.gateoverflow.in/course/view.php?id=7
• Exam Link: https://gateoverflow.in/exam/282/go-2022-databases-1

October 4-10

Revision, Rest

Exam Link:

October 11-17

Numerical Ability: Analytical Aptitude: Logic: deduction and induction, Analogy, Numerical relations and reasoning
Spatial Aptitude: Transformation of shapes: translation, rotation, scaling, mirroring, assembling, and grouping, Paper folding, cutting, and patterns in 2 and 3 dimensions

• Webpage for Numerical Ability
• http://classroom.gateoverflow.in/course/view.php?id=15
• Exam Link:

October 18-24

Computer Networks: Concept of layering: OSI and TCP/IP Protocol Stacks; Basics of packet, circuit and virtual circuit-switching; Data link layer: framing, error detection, Medium Access Control, Ethernet bridging; Routing protocols: shortest path, flooding, distance vector and link state routing; Fragmentation and IP addressing, IPv4, CIDR notation, Basics of IP support protocols (ARP, DHCP, ICMP), Network Address Translation (NAT); Transport layer: flow control and congestion control, UDP, TCP, sockets; Application layer protocols: DNS, SMTP, HTTP, FTP, Email.

• Webpage for Computer Networks
•  http://classroom.gateoverflow.in/course/view.php?id=1
• Exam Link:

October 25-31

Operating System: Processes, Threads, Inter-process communication, Concurrency, Synchronization, Deadlock, CPU scheduling,

• Webpage for Operating System
•  http://classroom.gateoverflow.in/course/view.php?id=5
• Exam Link:

November 1-7

Operating System: Memory management and virtual memory, File systems. 

• Webpage for Operating System
• http://classroom.gateoverflow.in/course/view.php?id=5
• Exam Link :

November 8-14

Linear Algebra: Matrices, determinants, systems of linear equations, Eigen values and Eigen vectors, LU decomposition.

• Webpage for Linear Algebra
• http://classroom.gateoverflow.in/course/view.php?id=10
• Exam Link:

November 15-21

Revision, Taking Tests. 

• Exam Link: 

---

November 22-28

Compiler Design: Lexical analysis, parsing, syntax-directed translation. Runtime environments. Intermediate code generation. Local optimisation, Data flow analyses: constant propagation, liveness analysis, common subexpression elimination. 

Calculus: Limits, continuity and differentiability. Maxima and minima. Mean value theorem. Integration. 

• Webpage for Compiler Design   
• http://classroom.gateoverflow.in/course/view.php?id=18 
• Exam Link: 

November 29 – December 5

Calculus: Limits, continuity and differentiability. Maxima and minima. Mean value theorem. Integration.

• Webpage for Calculus
• http://classroom.gateoverflow.in/course/view.php?id=11
• Exam Link: 

Revision, Solving tests

---

December/January

• Full length mock tests
• Time management and reducing careless mistakes must be done
• Closed book revision is important 

Mock Test 1 : December 12 

• Exam Link:

Mock Test 2 : December 26

• Exam Link:

Mock Test 3 : January 2

• Exam Link:

Mock Test 4 : January 9

• Exam Link:

Mock Test 5 : January 16

• Exam Link:

Mock Test 6 : January 23

• Exam Link: 

Instead of preparing themselves for M.Tech courses at IITs some of those who got good rank in GATE have been seen promoting their stuffs and even sharing referrals to coaching institutes. For any serious candidate preparing for GATE all information should be available in the GO blogs given below and many aspirants have even shared their full preparation experiences. Still many will be looking for “spoon feeding” and if you want to help them you can do at your own place – not here. By sharing your notes if you believe you are helping aspirants – 99% you are not.

https://gateoverflow.in/blogs

BITS HD 2021 FORMS ARE OUT.

• BITS HD 2021
• Exam fee details

Last Date	29/05/2021
BITS HD Online Test	26th & 27th June 2021

For more visit here: Important Dates

1. Admission can take either gate mode or non-gate mode or you can apply in both modes.
2. Apply for both computer science as well as a software system for this exam.
3. The exam date may be extended like last year due to covid-19  time.

All the best.

Here are the notes I have written during my preparation for GATE CS/IT. Future aspirants may find it helpful. These are elaborated notes, that one may go through to recapitulate stuff fast. I took help from standard books and online courses to put together these notes. As of now, only some chapters of Discrete Mathematics are uploaded. I will upload notes for all the subjects within a month. 

https://gatecsebyjs.github.io/

Sample note(on Combinatorics):  

https://drive.google.com/file/d/1K5DW0rZolcWfJbAMuZvWkvvTuezs4fEP/view?usp=sharing

 

Peace!

 

🌟Notes of all subjects uploaded🌟

Update 1(25/04/2021): Discrete Mathematics completely uploaded

Update 2(26/04/2021): Computer Organization and Architecture, Compiler Design uploaded

Update 3(27/04/2021): Theory of Computation, Databases uploaded

Update 4(28/04/2021): C Programming, Data Structures uploaded

Update 5(01/05/2021): Digital Logic, Algorithms uploaded

Update 6(02/05/2021): Computer Networks uploaded

Update 7(03/05/2021): Operating System Notes, Engg. Maths. materials uploaded