Most viewed posts in Interview Experience

The interview was conducted over Zoom video conference with 2 professors present. After the introductions, the following problems were asked from my selected topics – 

• Probability theory and Discrete Mathematics. 

Professor 1 on Probability Theory ( Time: 20 mins including introductions)

• Do you know what is a random variable?
• Can you define it precisely? 
• Now suppose you have a biased coin with the probability of a Heads being $p$ and the probability of a Tails being $(1-p)$ . How do you mathematically write the random variable for this?
• Now suppose we are doing an experiment where we toss the same coin $N$ times. What is the sample space of this? 
• What do you mean when you say Binomial distribution? 
• Can you find the expected value of heads for above problem ($N$ tosses of the given biased coin)?
• Okay, do the derivation.
• Is there any other method to find it? 
• Why do you say that you can add expected value of Bernoulli random variables?
• Do the experiments need to be independent (for us to be able to add them to get the expected value)?
• Calculate the expected value via the second method.

Professor 2 on Discrete Maths (Time: 15 mins)

1. You are given $n$ vertices. Each pair of vertices $(v1, v2)$ are connected via an undirected edge. How many edges will be in the graph if self loops are allowed? 

2. Suppose there are $n$ vertices and $e$ edges in an undirected graph. Can you say anything about the sum of the degrees of the vertices?

3. Suppose I tell you that $n$ is odd and each vertex has an odd degree, is it possible? Can you write the explanation.

4. Write down $a^2 + b^2 + 2ab$ $<=$  $k*(a+b)^2$ on the paper. Here $a,b$ are non-negative real numbers. Can you say anything about $k$?

5. Now change it to $a^2 + b^2 + 2ab$ $<=$  $k*(a^2+b^2)$ . Can you say anything about $k$?

Hints: https://gateoverflow.in/blog/10821/my-rough-work-during-the-interview-for-csa-research-iisc

BLOG INDEX

• Interview Details and Stage 1 (Coding)
• Stage 2 (Home Interview)
• Post Result Talk with Professor (about CDS/CSA, DREAM LAB, Research)

Date – 10-July-2020, Duration – approx. +45min (Between 10:45 am to 12 am)

Stages – Two (Online Test, Home-Interview),

There was Online Google Form asking for Preferences, SOP (why you have chosen preference), Projects List, Professional Website (LinkedIn etc.), Programming Skills profile link.

(You need a background, possible experience to select labs, because they have your profile at the time of interview and ask questions why this lab, why not this)

Labs allowing to CS/EE only – DREAM LAB, MARS LAB, VAL, CSL.

---------------------------------------------------------Stage 1

It consists of Basic Objective Question based on Engineering Mathematics and Discrete Mathematics.

Syllabus – (source CDS brochure) – Combinatorics, Linear Algebra, Probability, Statistics, Differential Equations, Plotting, Data Structures and Algorithms

Platform – HackerEarth

Pattern – 7 Questions (5 marks each), 5 Multiple choice questions, and 2 programming questions

Programming Languages allowed – C (gcc 5.4.0), C++, Java.

Time: Early Morning 7:30 to 8:30 am ( then non-stop 45 minute online test)

----------------------------------------------( round brackets are showing my thought process () )

Q1. A group of 12 people, consisting of 6 couples, have reserved a row of 12 seats at a movie theater. How many ways are there to seat these people if couples want to sit next to each other.

Options – 46080, 23040, 1200, 479001600

(My Reasoning: 6 group permutation then each couple permutation - 46080)

------------------------------------------------------------------------------------ 

Q2. The plot of $y=e^{-x}sin(2x)$

(well I used calculator to put x value and get y value)

( I can straightaway delete the option c, for other I went raw method)  (anyone knows better method can suggest)

Q3. Consider the system of equations

$x+3y-z=4$

$4x-y+2z=8$

$2x-7y+4z=0$

Options – No solution, unique solutions, infinitely many solutions, None of the above

(I got last two rows same on initial first row operation)

Q4. What is the sum of diagonal elements of the matrix  $\begin{pmatrix} 1 & -1 \\ -1& -1 \end{pmatrix}^{10}$

Options – 0, 32, 64, 128

(Eigen Value coming out to be = ±sqrt(2)) ( in hurry, and in morning sleep I have done raw matrix multiplication also)

-------------------------------------------------------------------------

Q5. You are randomly selecting one of two coins A and B and tossing it. Coin A is fair but Coin B has ¾ probability for tails. If after the coin toss you observe tails, what is the probability that you had selected coin B?

Options = 0.5, 0.6, 0.625, 0.4, None of the above

(applied Bayes theorem)

Q6. Graph Traversal BFS

Say you are given a graph with n vertices labeled with IDs 0 to (n-1). The graph data structure is provided as an adjacency matrix G of size n×n. The row i of the matrix corresponds to the neighbors of the vertex ID i  in the graph such that if there is a value 1 in the column j of that row, there is an edge from vertex ID i to vertex ID j , and if there is a value 0 , there is no edge between vertex i and vertex j.

Given a source vertex ID s  preform a breadth first traversal (BFS) of the graph and print the IDs of the vertices visited. The traversal of unvisited children from any vertex should occur from the smallest to the largest child vertex ID.

Sample Input
4
0 1 1 0
0 0 1 1
0 1 0 1 
1 0 0 0
1

Sample Output
1
2
3
0

( code template was provided with necessary declaration, reading input in adjacency matrix, we have to write main code) ( i haven’t done this question)

---------------------------------------------------------------------------------

Q7. Frequencies of even and odd numbers in a matrix

Given a matrix A of order N × N, the task is to find the frequency of even and odd numbers in matrix.

You will read the input and write the output from/to standard IO (console). Sample template code to read and write from I/O is provided for C, C++, java. Choose one of the languages comfortable to you.

Input format:

The data type of elements of A is INT. You read the matrix A from the standard console input as explained below.

The first row has the value of N, which gives the size of A. the following N rows are rows of A, with each row having N integers separated by a space. There is a trailing space at the end of a line.

Output Format:

You should output integers which are number of odd (OO) and Even Numbers (EE) in the given matrix to standard console output

OO

EE

Sample Input
4
1 1 1 1
2 2 2 2
3 3 3 3
4 4 4 4

Sample Output
8
8

(Similar template code is given)

(it was simple, just have to check odd and even number then have to count)

-------------------------------

Takeaway:

1. Do programming after Gate if you are in safe side. Else do both programming and interview preparation.
2. Keep practicing mathematics. As an engineer always practice math. It will never leave as long as you are in engineering. In fact, entire computer is built on mathematics model (Turing machine).

Please utilize your B. Tech Time properly, Do Labs properly, read subject (at least try) from Std. Books and guide your juniors. If you have done B. Tech then please utilize your MTech time properly.

-------------------------------------STAGE 2 - Home Interview

There was waiting room and other main interview panel.

Platform – Microsoft Team

My preferences was:

1. Distributed Research on Emerging Applications & Machines (DREAM LAB)
2. Cloud Systems Lab (CSL)
3. Video Analytics Lab (VAL)

( Reason was background subject related to DREAM then IOT which I have little bit experience)

There were 4 professor, 3 male, 1 female. Out of which 3 have asked me questions. (Rest 1 was of V.A.Lab I think)

As far as I remembered (No visuals from there side, and short name were there) – There was Prof. Yogesh Simmhan, Female faculty Prof. J. Lakshmi. Rest I don’t remember name.

They started with reading my application, then my lab preference (why this or that), projects, gate score and reason for Gap in year. ( they asked me reason for VAL, I said I have read Image processing subject in my B.Tech and done some projects related to video manipulation)

(after Interview I have seen notification that someone viewed my LinkedIn profile at the starting of interview, as provided in form)

So, then They started: (I will try to format questions as they have said as best as I can)

-------------------------------------------------------

P1 (first professor): So, we will start with Data Structures and Algorithm. It is fundamental subject and should be known by all.

(Q1) Suppose, we have an array of ‘n’ numbers, I have to take min 10 elements, what should be the algorithm and time complexity.

(well I was not prepared for DSA, but every system subject but still I have given Gate, I know things right.)

[ I started with explanation of First sorting the array and then indexing array for first 10 elements]

P1: What is the time complexity of your process.

[told about using sorting algo – quick sort O(n.logn) and then indexing O(1)]

P1: Can you reduce the time complexity; can you think of it in other way.

[I started with some non-sense (I think greedy type, he pointed out my mistake) then in last I changed to naming unsorted array and using linear search for first element and then using it for 10 times, which will give time complexity as 10 times of O(n)

P1: Can you reduce it further.

(okay reducing more, think Vijay think)

[ I said we have to search an entire array at least one time to look for min element so it will minimum take O(n) time]

( they have given me time to think and come to solution)

P1: Topic changed

(Q2) do you know about sparse matrix.

(well I was thinking I have heard that name before and then)

[ it consist of minimum element like that]

P1: He immediately pointed out my mistake, and then said about sparse graph, using zeros and one in matrix.

( I got the link to area in my brain for that topic)

[ then I told about general adjacency matrix, zeroes for no edge, 1 for graph edge between vertex]

P1: okay great. Can you draw adjacency matrix.

[ drew graph then matrix and showed]

P1: now as we see for sparse matrix, it is taking more space can you provide alternate data structure.

[yes, I described adjacency list][ they asked me to draw and show]

P1: In sparse matrix, we have just 1 but it can be any non-zero value, right. So whatever data structure you have given can it provide such value.

[I said yes, and said it is linked list node, along with node and address we can have another parameter in that node.] [ they asked me to draw and show]

(now level increases.)

P1: Okay, great. Now I have vector of ‘n’ number and I need to multiply that vector with data structure you have provided. Like we do in adjacency matrix and matrix multiplication. Can your data structure do that.

[ Initially I asked him to explain one more time. Then I formulated first matrix multiplication. M as adj matrix and B as vector ( I asked vector to be column vector to support multiplication) then showed A(n*n) * B(n*1)

Then I took adj list data structure and …………]

( I know I have struck there but whatever my thinking process and direction I keep on explaining)

( there was google doc where I have to show him doing that)

[ I said we will traverse node by node, look for node number and then multiply it with that index in vector only)

( okay great, bolne ko to kuch bhi bol skte he, esa kr lo wesa kr lo, par ab bol diya ab kya)

P1: great. Can you construct the program for that in the google docs.

(I was like, seriously?? Right now?? I don’t know where all my programming skills have gone to may be still sleeping for morning routine) ( ham bhi kha haar maan le wale the)

[ I tried, started, got confused, got lots of question what should be struct data name, what is node name, what is node header. Then he said just right main programming construct, you know C. well okay. I again started righting adj matrix code but then changed to traversing the linked list code. Wrote few lines of loop. He said okay we can stop now.]

P1: asked another faculty member whether he wanted to asked me about video lab or not. He said not needed.

P1: then he asked female faculty to ask me about OS question.

( I was like, okay I know OS, I can do that good)

------------------------------------------------------------------ 

P2 (female faculty) : Vijay, do you know OS, how much have you read.

[ I said I have read basic concepts of OS and covered GATE syllabus topics]

P2: what is time sharing scheduling algorithm in OS.

[ I confirmed whether they are asking for Round Robin or not.]

P2: she said to explain it

[Explained arrival of process, ready queue, time quantum, preemption and execution till completion]

P2: Can you determine parameter by looking at that we can say the time quantum gives fair chance for every process or not.

(from now onwards, deep thinking process arrived)

[ I tried to explain her, having n number of process they will execute one by one ……]

She interrupted and explained what she is asking for.

[ I said we can calculate time quantum if we have given n number of process, context switching time, to allow fair share for all process]

She again explained that What is the parameter or ratio by which looking at that we can say that time quantum is fair for all process or not.

[ I told her about using turn around time, average turn around time to check if all process is executing efficiently.]

She asked what is turnaround time.

[ I told her basic definition]

Then she explained the effect if some processes are having large burst time or some having less. ( as far as I understood it was like convoy effect in fcfs type). She said how in that you can say turn around time will be that parameter.

[ now I have accepted my invalid point. I asked whether we can use some combination of waiting time or turn around time]

She again explained that she is looking for parameter by seeing it like if I say it is greater than 1 then we can say it fair or less than 1 not fair like that.

( now I was asking God for some help, to show some mercy and path to think, but God was busy fighting Corona)

[ Now I got stuck, completely blank, I asked for some hint]

How can you determine which process should execute or are waiting long enough to affect their performance?

[ meanwhile I said to her about using aging to determine priority whether they are waiting long enough or not required attention]

( I think aging is bit out of context for current question)

She said expected value or probability you can find for that.

[ I told about using burst time for calculation, then finding expected burst time and using that value as time quantum]

( yes I know, I was shooting arrows in dark, but I have to think right, If I stop then my brain will stop thinking at all)

She asked again how will you determine the burst time of process. Do you think process already have burst time before execution.

( I was like, well in gate question I have seen burst time before execution)

[ I was again started saying by seeing instruction whether they require cpu time or io time and calculating that, we can look for that instruction]

( I have seen expected burst time in SJF but at that as we are talking for round robin it doesn’t struck my mind)

She was like, how will you do that, suppose we have data instruction or require processing of the data in that case.

( I again chanted similar thing, looking for instruction and all)

She said suppose we are doing 3 by 3 matrix multiplication having large value of data it will take time. But again thing like we are having large matrix multiplication then in that how you will determine.

( I was like ohhh, ye kya ho gya, hamre jaal me hum hi faste jaa rhe he)

[ I said time complexity initially, but interrupted and then I explained my mistake and accepted it]

(She was nice, explained me properly, gave time to think, corrected my wrong thinking, In the end she was like smiling at my acceptance of mistake. And I was still thinking for some point to come back)

She said we should stop now, no problem and passed me to next interview.

---------------------------------------------------------------------- 

P3: do you know distributed system

[ I said I have read in B. Tech and explained working of Distributed system in short and RPC message passing]

P3: sounds great, so do you know basic synchronization concepts

[ I said yes for OS, but I don’t remember for Distributed system]

P3: yeah no problem. Concepts are same. It works like OS. So can you explain reader-writers problem

[explained about readers process and writer process]

He interrupted me asked me about synchronization problem involved.

[ I said 4 condition related to it]

He said okay. He asked do you think it gives equal chance to both reader and writer.

[ I said if we give priority to reader then writer may starve, or to writer then reader may starve]

Okay. Can you write the sudo code for reader writer synchronization solution in google doc.

[ okay, started writing meanwhile keeping on explaining whatever I was writing and why I was writing]

He interrupted me find mistake in my code where I have written mutex(x)….code…..mutex(x)

He said do you know semaphore and its function wait (), signal ().

[I immediately got my mistake and said sorry and corrected it down(x)….code…..up(x).]

[ meanwhile I was initializing binary semaphore x, but confused in spelling of semaphore or semafore.]

He said no problem in spelling just write rest of code.

( I was like why, here and now, what happen, even silly spelling mistake)

[I wrote all the code]

He asked suppose writer is in database and readers got suspended. Larger num of readers. So how they will resume their execution and in what order.

[ I explained about suspending list in semaphore and fifo way to wake up the process]

He further asked about priority in which reader and writer will be allowed.

[ I said if one reader is already entered into database then slowly all readers will execute first then writer may get chance]

P3: So do you know graph coloring problem. And its use?

[ I explained it in short manner of using it to color the node. And said I have seen its use in register allocation in compiler]

P3: can you explain graph coloring algorithm.

[ I said I don’t remember the algorithm, as I have solved question in rough manner and explained that manner of identifying large clique, using color and reusing them unless necessary.]

In the last he asked me whether I know programming or not.

[ I said I have done competitive programming 2 year before and from past 2 years I was focusing on Gate but I know basic programming.]

( and it ended, they disconnected me)

--------------------------------------------------------------------- 

Takeaway:

1. As I have felt, they were looking for how far I can think, because that OS question seem like research itself. How I formulate my answer and explain clearly. They were cooperative, giving time, explaining, correcting mistakes.
2. Basic Gate preparation will not help much, you have to pick up book and start reading out after Gate (if you haven’t). I have read OS for basic topics but still you have to try.
3. I was calm and trying to think hard for solution but still at that moment it was just not coming up. So, it is very much necessary to answer properly. Practicing how you will give the answer, starting from basic point to slowly increasing level with clarity.
4. At least revise all your short notes once after Result and practice math.

If nothing happens, you don’t get selected no problem, you got chance and experience. You can improve further building on it;.

Result: declared in the evening, got mail in morning. Selected.

GATE Score – 807, EWS

---------------------------------------Post Result Talk

Next day Prof. Yogesh Simmhan (Dream Lab) called me for this good news, my performance and discussed about its lab, department preference I can change if I want, what they will do in lab etc.

• He asked me whether I have visited the lab page or profile page and I am interested in it or not. (dream lab was my first preference and interview was little bit about that)
• About Lab – He said Lab overall works on Distributed System. Every few years idea of distributed system keeps changing, new technology emerges, and last few year IOT has been on emerging areas that is expanding. So we have multiple projects going on IOT, some of the newer ones have to do with how can you, for example, make use of Raspberry Pi class device, can be deployed as a part of smart cities, even for example Drones, we have projects coming around drones. IISc has new center on Autonomous computing that’s coming up, so for that we are trying to examine how drones, these flying platforms can we seen on as computing platform. We think of drone as flying platform, but to me a drone is nothing but a mobile phone (with flying capacity). So, we have mobility aspect of it and we also have sensors sort of video camera and so on that are modeled on the top of phone and flyer on.
• Some of Problems we are looking at how can you actually do some of the computing at the top of say video streaming, maybe even doing some deep learning …. So on, on top of the drone platform itself. And then there is some system aspect of it so how do you tradeoff between parallel computing on top of the drone itself as energy efficiency, right because drone has only captive amount of energy which you can use for flying and computing. And if you do too much computing, you might actually reduce flight time and so on. And how can these drones actually do task co-operatively, not just observational task even computing task co-operatively. So, can you actually move data from one node to another and then sort of distributed computing, you can think of flying Hadoop cluster right, as what drone could be considered as. Lot of interesting problem around IOT and drone computing like we are starting to look into. Some of these also have lit bit flavor of Machine Learning and Application domain for us because of anywhere and everywhere. (So, it is kind of thing you will be interested in?)
• Interest - One thing I can set of tell you is that one way to think about since you applied for Research program, it is not course program, right which means that the lab that you join is way more important than the department you join. Research student take typically one semester of course, and three semester or almost one and half year is spent in research lab doing research. Courses can be taken in any department, IISc doesn’t restrict you saying if you join a department A then you can only take course from A. In fact, many of my students take courses like operating system in CSA department. It is very flexible. What really matter is the research lab you join and the kind of research you do. That is why maybe doing little bit of homework on that and understanding what your interest are would be helpful
• Department – One thing I can tell you is system department in computer science typically looks at more classic computer system perspective like architecture and operating system. They are parallelly good at it. (some professor name). what the CDS work on the newer system like cloud computing, big data platforms, IOT, and so on. So that is the set of difference. If you like classic operating system and you like to work on Linux kernel and so on something like CSA might be good. If you want to set of do the next higher level, if you want to see like how tens of hundreds of distributed systems could be working co-operatively together to solve emerging problems. Things like edge computing drone computing didn’t exist five years back and cloud computing didn’t sort of prevalent ten years back. But we use fundamentals idea about operating system because at the end of the day your synchronization primitives are going to be similar whether it is one-two thread on single processor or across hundred machines across a wide area network, in terms of memory you will be going to network for coordination and so on. That I would say is set of key difference between some of the CSA based systems lab and the CDS system lab. (that is why think about it)
• Department Preference – what IISc will do is IISc will give only single offer based on department priority that you have chosen. They will not give choice to you, let say both CSA and CDS are willing to take you. If one department is higher choice you only get a single offer from that department, and if you decline it, it is declining entire IISc offer. Now you have chance to speak with faculty at both CDS and CSA, so do a little bit of homework and if you strongly feel that something at dream lab will be right lab for you. You have time till Monday to change department preference. But do look through the lab because that’s going to be like I said critical part, what does the actual area you want to work on and based on that You should chose your department where that lab is present.
• Advisor/LAB – I would be one of your primary choices and even within the department since you have given the priority order, we would sort of respect that, but we also encourage to talk to couple of other labs, so that you enough information and choice is up to you. If you are interested in dream lab at CDS, I will be happy to take you (based on performance in interview and resume). I think you have one month after you join to finalize your lab after you join the department. It is two-way street, both the lab must be interested in you and you must be interested in lab, if both of these happen, then you will be able to.
• Students/Research – way we do interview we want to understand the overall skills of the student because research itself is such a fast-moving area, we don’t want to hire someone who has narrow set of skills. At the end of the day we do not expect student to be set like sort of extremely talented when they come but must have sound fundamentals and they should be really passionate about what they wanted to do. Because it was like what Edison said Innovation is set of 99 percent perspiration and 1 percent inspiration. As long as student willing to work really hard, they enjoy what they are doing and they are interested in system research. IISc or Lab or Department will provide the right environment for you to thrive. Sometimes student design their own projects and they come in and say this looks nice but I wanted to do something related to this. That way you can carve a whole new topic for yourself, that is the kind of flexibility we offer. Research is not like a production line; it is not a kind of algorithm that you follow. Research is all about creativity, trying to find about very interesting problems and trying to solve that to the best of your abilities. All the students and faculty are hardworking and they expect a lot. The reason we are able to compete with some of the top 100 university in world is not just because we have right students but we have hard working students.

Thank You for Reading. Hope It helps. Constructive Views are welcomed.

I wrote a blog on quora about my written test and interview experience at IIT Madras. Hope it helps next year aspirants.
https://sktdt.quora.com/IIT-Madras-MS-CSE-Written-test-and-interview

Edit: IIT Delhi M.Tech. in Computer Technology(EET) Interview

https://sktdt.quora.com/IIT-Delhi-M-Tech-in-Computer-Technology-EET-Interview

IISc CSA Intelligent Systems (M.Tech Research) Written Test and Interview

https://sktdt.quora.com/IISc-CSA-Intelligent-Systems-M-Tech-Research-Written-Test-and-Interview

Platform: Google Meet

Research Stream Preference: Intelligent Systems (background subject: linear algebra and probability theory)

There were three professors in the panel, only two of them asked me questions. I will refer them by I1 and I2.

I1: Read out my application, mentioned my GATE score and rank, department preferences, labs selected, and asked about my BTech CGPA

He asked me why I did not apply for direct PhD and explained me benefits of doing direct PhD.

I1: What are the subjects that you have prepared for the interview?

Me: Sir, I have prepared background subjects linear algebra and probability, and familiar with subjects in GATE syllabus.

I1: I will ask you questions in probability first. Tell me if you have referred any standard book for probability?

[I mentioned the Sheldon Ross book]

I1: There are two types of random variables: discrete and continuous. Can you tell me what is the difference between the two random variables?

Me: For discrete random variables the values that the random variable (X) can take are countably finite and for continuous random variables the values are uncountable.

I1: (He was not impressed with my answer) Are you sure that is the correct statement? And is it written in Sheldon Ross book?

I1: Why do we name it continuous random variable? Why not call it uncountable random variable?

(We had discussion about this for about 5 minutes then he said that we call it 'continuous' because the cumulative distribution function for the random variable is a continuous graph.)

I1: Coming to normal random variable, can the peak of the bell curve have value greater than 1?

Me: The sum of probabilities in the range will give the total probability = 1. So total area under the curve should be 1. But I am not sure if peak could be greater than 1.

(Interviewer was not convinced with my answer. He gave me a few hints but I couldn't answer it well)

I1: What will be the value of normal random variable for $X = x$

Me: $P(X=x) = \frac{1}{\sqrt{2\pi \sigma^2}} e^{\frac{-(x-\mu)^2}{2\sigma^2}}$

I1: Right. What will be the maximum value for this? (assuming mean=0 and std=1)

Me: $\frac{1}{\sqrt{2\pi}}$ at x=0.

I1: Tell me about the binomial random variable.

Me: Told

I1: Can you say that binomial random variable is a limiting case of normal random variable? (If n is very large then will the binomial random variable become similar to normal random variable?) Prove it.

Me: I said yes but I couldn't prove the statement.

Now, the other professor took over and asked me questions on linear algebra

I2: What are eigenvalues and eigenvectors, can you define them?

Me: Sir, these are vectors whose direction remains unchanged after transformation. They might squeeze or stretch but the direction remains unchanged.

I2: Can you write the equation that you would use to calculate the eigenvalues and eigenvectors. And also explain the above definition with respect to that equation.

Me: Told

I2: Do these eigenvalues exist for every matrix mxn ?

Me: No sir, they are defined for only square matrices.

I2: Yeah, can you tell me why?

Me: In $Ax = \lambda x$ if A is rectangular matrix (m, n) and x is a (n, 1) column vector then Ax would be m-dimensional column vector (m, 1) which is different from RHS, i.e $\lambda x$ is a n-dimensional column vector (n, 1).

I2: Can you workout the above equation and show me how you will go about calculating the eigenvalues.

Me: $Ax = \lambda x$

$Ax = \lambda I x$

$(A-\lambda I)x=0$

$det(A-\lambda I)=0$

Now, we will solve for $\lambda$

I2: Okay, I understand the first two steps but why have you made $det(A-\lambda I)=0$ in the third step.

Me: Since we have $(A-\lambda I)x=0$. To solve this equation, x represents some combination of column vectors of $(A-\lambda I)$ that equate to zero. So the column vectors are not independent and hence the rank would be less than n. That would mean the determinant of (n x n) matrix should be zero if we want a non-trivial solution.

I2: Okay, now suppose I take transpose of A. Will the eigenvalues change?

Me: No sir. If $det(A-\lambda I)=0$ then $det((A-\lambda I)^T) = 0$ because the determinant remains same after transpose. Now, $det(A^T-\lambda I)=0$. Hence, the eigenvalues $\lambda$ will remain same.

I2: Okay, so you said that determinant remains unchanged after transpose. Is that true for every matrix?

Me: Yes, sir

I2: Do you know about row echelon form or reduced row echelon form. Can you name some common matrix operations?

Me: Yes sir, we can exchange two rows/columns, we can subtract/add multiple of some row/column and add to the other row/column.

I2: What would happen to the determinant if we apply these transformations.

Me: Sir, the determinant would remain unchanged.

I2: Can you take a simple matrix and show with a simple operation that determinant remains unchanged?

Me: I tried to work out a proof with a simple 2x2 matrix but couldn't clearly do it. He did give me some hint. Later I showed him an example that in a 2x2 matrix if we do $R_2=R_2-3R_1$ then the determinant value remains same.

(He was looking for a formal proof but I couldn't do it due to panic so I just showed him a simple worked out example by taking a 2x2 matrix)

The interview ended here, it lasted about 45 minutes.

My suggestion to future aspirants will be to prepare the topics from standard books right from the start of their GATE preparation. The interviewers focus on concepts and proofs which are very well explained in the standard books.

Verdict: Not Selected

Background: B.Tech in CSE from WBUT (2017) CGPA – 9.1

Work Experience: Subex, Bangalore, and Cognizant, Kolkata.

GATE Score: 608,  Year: 2020, AIR: 1746

Interview date: 15th Dec 2020 online on Webex.

Shortlisting criteria: Visit https://cse.iith.ac.in/admissions/mtech.html for more details.

Admission to the 3-year M.Tech. Programme will be based on an entrance exam and/or interviews for shortlisted candidates. The department may use various application parameters including (but not limited to) GATE score for shortlisting candidates. Interviews test the candidates on standard topics in a Computer Science syllabus (data structures, programming, theory of computation, algorithms, networking, OS, DBMS, etc). Prior research exposure and/or industry experience are also considered while selecting candidates in these categories.

I received mail for the interview on 11th Dec 2020. There were exactly 18 candidates who got shortlisted.

In the mail, they didn’t mention which topics to prepare.

I had my interviews at 3.30 pm and it lasted for around 15 minutes.

There were three profs in the panel.

Intv1: Introduction.

Intv1: Experience and responsibilities at work. 

Intv1: Reason & motivation for M. Tech. 

Intv1: They told they have project in “Quantum communications” and “5G Testbed” only and there is no ML related projects to work on and asked whether I’m okay with it.

Intv1: Asked the subjects of preference. Also asked if I prepared CN.

But I told that I’ll be comfortable with DS, ALGO, and DBMS.

Intv1: How to represent Graph DS? Time and Space complexity to store.

Intv1: How to check if an edge is connected in a Graph? Compare time complexity of adjacency matrix and list approach. Can I improve on the time and space complexity in case of very large graphs.

Intv1: Time complexity to find the rank of matrix of a large graph.

Invt2: Meaning of rank of a matrix and rank-nullity theorem.

Intv3: Bayes theorem.

Intv3: Graph search and traversals.

Total Selected: 3 out of 18 under two different projects.

Result: Selected under the project “Quantum Communications”

Here is the long struggle fruit :

I owe this success to GateOverflow and all its members.

Thank you Arjun Sir for creating this platform and allowing students like me to achieve their dreams and get the highest quality of CS knowledge even if one is not from a good college absolutely at no cost. I was fortunate to meet him at IISc, 2017.

The amount of knowledge I learned from answers and comments from members of GO is amazing. I want to thank all of the peers, seniors, and mentors of GO for their selfless contribution to the platform.

“GateOverflow is the key to open GATE and other opportunities” 

P.S: I declined the CSE offer because AI dept project was more interesting.

IIT, Madras GATE Overflow Interview Experience Links: 2016 to 2021

IIT, Madras Other Interview Experience Links: 2008 to 2020

National Institute of Technology, Tiruchirappalli invited 30 aspirants for interview/counselling on 7th July 2017. They released this notification on 15th June 2017 on their website, with very limited information. It was not at all clear what will exactly happen on 7th July until we reached the campus.

I reached Trichy a day before, just to be on safer side. My brother was accompanying me and we had a booking in Breeze Residency, a hotel which was less than a kilometre away from TPJ (station code) railway station. However, later I learned that the retiring rooms of the station were equally good. You can make your pre-bookings of the retiring room from IRCTC website.

We decided to spend our day visiting tourist places in Trichy. We learned from the housekeeping staff that Trichy is full of places with religious significance. First, we visited Sri Ranganathaswamy temple in Srirangam, which is the largest active Hindu temple in the world. Later, we visited Rockfort temple which was situated on huge rock mountain at a height from where the entire city was visible. We were done by late afternoon. For the rest of the day, I just relaxed and prepared myself for the next day.

The admit card released by NIT Trichy mentioned interview/counselling timings as 3:30 pm to 5:30 pm. However, the notification of shortlisted student said that the reporting time is 10:30 am. We decided to reached there before 10:30 am, again just to be on safer side. Later, it turned out to be a right decision. It takes roughly 45 mins to reach NIT Trichy Campus from railway station/bus stand. When I reached the department, they directed me towards the conference hall and asked me to wait there with others. Two persons from the Institute entered the room and asked all of us to show them our documents one by one. I was asked to be the first.

The objective of this phase was to award marks to students in different categories. Different categories include our score in undergraduate, GATE score, any award or research paper published and lastly the interview. They had predefined criteria, based on which they were awarding marks to each student in each category except for the Interview.

Later, we were taken to their meeting room for the interview. This time I was fourth in sequence. Finally, they called out for me. I entered the room, and my heart sank seeing more than 15 professors and associate professors in front of me. However, calmness of their face made me feel comfortable. HOD on the far end of the conference table asked me to take the seat. And the series of questions began.

HOD: What is your GATE Score?
Me: 651

HOD: Please introduce yourself.
Me: I wasn't expecting this question, but I tried to confidently introduce myself. 

HOD: Have you got any offer of admission in M.Tech from any institute?
Me: No ma'am, not yet.

HOD: What is your research interest?
Me: Algorithms and Data Structures.

And just when those words came out of my mouth Dr K Viswanathan Iyer turned toward me and with a pause started to ask questions

K: Are your familiar with Graph Algorithms?
Me: Yes Sir.

K: Explain Depth First Search.
Me: Explained, in simple words without using any jargons.

K: Applications of DFS?
Me: We can use DFS to find the paths from point A to B in a graph.

K: Please be more specific.
Me: Finding all possible paths between two nodes in a graph.

I was disappointed by myself for giving such a simple and obvious application. I should have given a much better application that was a bit research oriented.

K: Explain Breadth First Search.
Me: Gave my explanation in a comparative style. Comparative to the explanation given for DFS.

He looked convinced.

K: It is given that there is a negative edge weight cycle in the path between two nodes. Why there cannot be a shortest path between these two nodes?
Me: Gave an argument that there will always be a shorter path between those two nodes by going around the negative edge weight cycle one more time.

He acknowledged my answer by nodding.

K: What is Dynamic Programming?
Me: Explained the crux of Dynamic Programming.

K: There exists a shortest path between two nodes 's' and 't'. There is a node in that path, say 'x'. The path from 's' to 'x' will be the shortest path or not.

I asked him to repeat the question for me, as I could not get it with clarity. He did it with patience. But I took time more than their expectation to understand the question. So they decided to move one. Had it been the case, I could understand the question a bit more quickly, I could have answered that as well. 

HOD: What would you choose if you get an offer for both M.Tech and M.S (by research)
Me: Answered

HOD: That would be all. Thank you, Prateek.
Me: Thank you, ma'am. Thank you, everyone.

It was a very short interview of 7-10 mins. When it was all done, they asked us to leave and said that they will update the result on the website in a week or so.

It was a really nice experience. Here are my takeaways from this experience.

1. Learn about at least one important application of a theoretical concept. It should come out from the top of your head whenever asked for.
2. Take your time to answer the questions but learn to understand questions as quickly as possible.
3. Be very very clear with your explanation. We were not asked to explain our concepts on board. Thus, it has to be just what it is, nothing more nothing less. 
4. Lastly, do not be very hard on yourself. They very well understand the gap of knowledge between a teacher and a student. They never expect you to fill it, but just to bridge it.

Background: B.Tech in CSE from WBUT (2017) CGPA – 9.1

Work Experience: Subex, Bangalore, and Cognizant, Kolkata.

GATE Score: 608,  Year: 2020, AIR: 1746

Interview date: 12th Dec 2020 online on MS Teams.

Shortlisting criteria: Visit https://ai.iith.ac.in/mtech-admissions.html for more details.

For admission to the program, there will be a preliminary shortlisting depending upon the academic background and GATE score. Candidates who satisfy the shortlisting cutoff need to appear for a written test and/or an interview. 

I received mail for the interview on 8th Dec 2020. There were exactly 10 candidates who got shortlisted.

In the mail, they mentioned which all topics to prepare – 

The interview will test, among other things, basic concepts from foundational topics in AI including (but not limited to) programming, linear algebra, probability, calculus and algorithms/data structures.

I had my interviews at 2.30 pm and it lasted for around 15 minutes.

There were three profs in the panel.

Intv1: Introduction.

Intv1: Experience and responsibilities at work. 

Intv1: Reason & motivation for M. Tech. and knowledge of AI 

Intv1: Machine learning algorithms that I know of. B. Tech project and why AI?

Intv1: Describe how the Support Vector Machine works.

Intv1: Naive Bayes classifier and Bayes theorem. 

Intv2: Rank of matrix and how to find that & it’s significance. The rank of an Identity matrix.

Invt2: Meaning of Linearly independent vectors.

Intv2: Conditional probability of throwing a fair dice multiple times.

Now, Invt3 asked 5 MCQ questions by sharing his screen which are from Quantitative aptitude and Engineering Maths.

Invt3: How many rectangles are there in this diagram? (Diagrams were similar as shown below.)

Intv3: Generalize and deduce a formula for the previous question.

Invt3: Find the angle numbered 8 for the given diagram. (Diagrams were similar as shown below.)

Invt3: Is 961 a prime number? Explain the algorithm that is used to solve the problem.

Invt3: $\int_{+\infty}^{-\infty} sin(x)\ –\ cos(x) dx$

Total Selected: 4 out of 10 under four different projects.

Result: Selected under a project which is an application in the field of Computer Vision.

Here is the long struggle fruit :

I owe this success to GateOverflow and all its members.

Thank you Arjun Sir for creating this platform and allowing students like me to achieve their dreams and get the highest quality of CS knowledge even if one is not from a good college absolutely at no cost. I was fortunate to meet him at IISc, 2017.

The amount of knowledge I learned from answers and comments from members of GO is amazing. I want to thank all of the peers, seniors, and mentors of GO for their selfless contribution to the platform.

“GateOverflow is the key to open GATE and other opportunities” 

IIT Bombay, GATE Overflow Interview Experience List: 2017 to 2020

IIT, Bombay Other Interview Experience Links: 2013 to 2019

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…

I gave IIITH PGEE – 2019 on 28th April,2019.

Written Exam consisted of two sections – 1. General Aptitude  2. Subject Paper (Computer Science in my case). (More information is here :https://www.iiit.ac.in/admissions/postgraduate/monsoon/syllabus)

General Aptitude section was of moderate difficulty. I was able to do most of the questions and left only 4-5 of them. Subject paper was easy to moderate. About 95% of the questions were from previous year GATE papers. While preparing for GATE, I have solved almost all previous year questions from GO PDF, so the paper seemed easy to me. I was sure that I will be shortlisted for the interview. So I started preparing for the interview right away.

I was right. I received interview call letter on 10th May, 2019. My interview date was 10th June, 2019. I had exactly a month in my hand to make sure that I don’t screw up my interview. (I will share my preparation strategy in detail later)

10th June, 2019 – The Judgment Day

I reached the IIIT Hyderabad Campus at 8:00 AM. All the candidates were standing outside a hall, staring at a list on which our names and interview panel allotted to us were mentioned. I was allotted Panel-1. I entered the hall. After a while, a professor, who was in-charge of admission process, came in. He entered and started walking across the hall barefooted (I guess he was completing his morning walk). He then told us about the selection process, research facilities and placement opportunities. He addressed all our questions regarding interview process, difference between MS and M.Tech, stipend, fellowship etc; however, he didn’t disclose details like selection criteria, cut off, result date etc. After that, we were taken for registration, and then I waited for 3 hours for my turn.

During 1st hour, my friend asked me some C programming questions on WhatsApp and I was chatting with him, discussing those questions. After that I sit back for 2 hours relaxing my mind. I saw a lot of people revising their notes, while some of them were relaxing just like me. At first, I thought of revising some important concepts and pseudo code of graph algorithms, but then I feel what I will revise right now is not going to be asked in the interview. (Spoiler Alert – I was right)

(Side Note: My friend, whom I mentioned above, got into MS programme in IIT Kanpur. You can see his interview experience here : https://gateoverflow.in/blog/8079/iit-kanpur-ms-interview-experience)

The wait was over and I, along with 2 other candidates, were taken to the interview hall. One guy went before me, and then it was my turn. I took a deep breathe and entered in. My interview went for about half an hour.

The Interview

It was a panel of four professors, out of them one was a lady professor. (I’m gonna refer to them as P1, P2, P3 and P4)

On the table there were a bunch of flowers and a bowl of eclairs (May be kept there to break our nervousness)

I greeted them with a smile (probably a fake one as I was not feeling to smile at all).

P1: What’s your name?

Me: Astitva Srivastava

P1: That’s a nice name.

Me: Thank you Sir.

P2: Have a seat. Sign the attendance sheet, and give me your certificates.

Me: *Rushing through my documents in a hurry*

P2: Give me the whole folder.

Me: *I gave the folder, thinking now they are going to analyze me completely*

P2: What’s your first preference, M.Tech or MS?

Me: Sir, MS (Smiling inside that now he’s going to ask “Why MS?”  and I prepared a really good answer for that)

P2: *To my surprise he smiled and didn’t ask “Why?”* Instead he asked, “What’s your favorite subject?”

Me: Sir, Algorithms.

P2: *Gave a gesture to P1 that you slaughter him first*

P1: *Asked me to come on white board* You are given a matrix M of integers, and a number K. Write an algorithm to find any sub-matrix of M whose elements sum up to K.

Me: *I came up with an approach but it was not efficient. I was looking for a solution involving Dynamic Programming.*

P3: OK, we need to know what you’re thinking?

Me: Sir, I am trying to come up with a dynamic programing solution. Right now I only have a brute force approach.

P1: No problem, tell me the brute force approach.

Me: Sir, for each element in matrix M, I will consider a sub-matrix starting from that element and then I will loop further to make that matrix grow cell-by-cell and keep adding the elements and stop when I get sum equals to k. 

P1:  OK, so how will you improve it further?

Me: Sir, there will be instances when part of sub-matrices will overlap. We can memoize the sum of that part and use it later to reduce the complexity of adding up the same elements again and again.

P1: Write pseudo code for that.

Me: *After struggling for a while* Sir I am not able to think of a way to perform memoization.

(I think I did right to give up so that they can ask me other questions instead of wasting the time)

P2: You didn’t studied DP?

Me: Sir I did, but there all a lot of problems. I have studied only some classical problems. Right now my mind is not going in a direction that can give me a good approach.

(I tried to be as honest with them as needed)

P1: *Smiling* OK leave DP. Devise a new algorithm to sort numbers using stack. You can take as many stacks as you want. Numbers are arriving in a stream, not stored in an array.

Me: *After thinking for a minute* Sir, I will use two stacks, say S1 and S2. Then I wrote a pseudo code somewhat like this:

                      (1) Take a number from the input stream, lets call it x.

                      (2) if (Top(S1) >= x OR S1 is empty) : Push(S1,x)

                      (3) else: y = Pop(S1)

                                  Push(S2, y)

                                  Goto (2)

                      (4) while (S2 is not empty): 

                                 z = Pop(S2)

                                 Push(S1, z)

                       (5) Repeat from (1) to (4) until all numbers are processed.

                       (6) Pop out all the elements from S1 to the output stream.

(Then I explained them the whole approach by taking an example)

P1: OK, what is the worst case complexity of this algorithm?

Me: Sir, O(n²)

P3: *trying to distract me* No no, you’re wrong it can’t be O(n²).

Me: *Explained the worst case. He seemed satisfied*

P3: The complexity you are telling about, on what factor it is based?

Me: Sir, it is based on the number of comparisons.

P3: Why we don’t consider clock cycle time, or complexity for operations like adding, multiplying etc.?

Me: Sir, we analyze the algorithms on the basis of RAM model of computation, and all of our assumptions are based on this model.

(In case you don’t know about this, take a look : https://www8.cs.umu.se/kurser/TDBA77/VT06/algorithms/BOOK/BOOK/NODE12.HTM)

P3: OK, so you’re saying that if we improve our hardware, algorithms will not improve in any way.

Me: Sir, speed of the algorithm or program will increase but complexity will remain same.

P3: Right. Well, apart from number of comparisons on what other factors the complexity of the algorithm you have written will be based on.

Me: I think only on number of comparisons.

P3: Are you sure? What about number of push and pops. Wouldn’t push and pop contribute towards complexity?

Me: *Acting over smart* Sir each push and pop will take constant time.

P3: No no, I’m talking about NUMBER OF PUSH AND POP OPERATIONS. Just tell me yes or no, will complexity depend on it or not?

Me: *Realizing my stupidity* Yes sir, it will depend on number of push and pop operations too.

P3: OK.

P2: OK, we’re done here……

Me: *Thinking, Whaaat?? Is that it?? Ask me more*

P2: *to P1* …...Sir, do you want to ask anything else or should we stop?

P1: Hmmmm...ok. I will ask some maths. What is a bijective function?

Me: Sir, the function which is both injective and surjective.

P1: You are given two sets A and B. There are ‘n’ elements in both sets. What is the number of bijective functions possible from A to B?

Me: *After thinking for a while* Sir, n! (n-factorial)

P1: No. 

(I’m still wondering at this moment while writing this post that why he said “No”)

(Before I could explain why I am getting n!, he bombarded another question)

P1: So, Astitva have you studied linear algebra?

Me: Yes Sir. (I was happy because I prepared linear algebra well)

P1: OK so tell me, what do you mean by the rank of a matrix?

Me: Sir matrices are a way to represent linear transformation, so if we take a column vector and perform linear transformation on it using a matrix M, and if the output vector lies in a K dimensional space, then we say that rank of matrix M is K.

P1: *Gave me a blank look*

Me: *I continued* If we have a matrix, then the number of linearly independent rows or columns in it is called it’s rank. We can find the rank by looking at number of non-zero rows in Row-reduced Echelon form of the matrix.

P1: *Gave me a matrix and asked its rank*

               |  1   1 |

               |  2   2 |

Me: Sir, the rank will be 1.

P1: How can you say this without reducing the matrix in Echelon form? 

Me: Sir the two vectors in the matrix are linearly dependent. So one vector can be written as linear combination of another vector and then can be reduced to zero vector.

P1: What do you mean by linearly independent vectors?

Me:  If we are given a set of vectors say v1, v2, v3 ………….…….. vN and : 

        c1.v1 + c2.v2 + c3.v3 + …………………. + cN.vN = 0, if and only if the constant ci = 0 for all i, 1<=i<=N

(I wrote the above equation on board)

……...then the given set of vectors will be linearly dependent

P1: Linearly dependent ???

Me: Sorry Sir, linearly independent.

P1: OK. That’s it from my side.

Me: *addressing the panel* Anything else you want to ask? Operating systems, Theory of Computation etc…

P4: You’re a singer? I saw your certificate.

Me: Yes Ma’am.

P4: Can computers sing?

Me: Yes Ma’am, there are some artificial intelligent systems that can sing and compose new music.

(I remembered the one I saw on YouTube)

P4: Can they sing better than humans?

Me: Not now, but I believe in near future they might.

P2: Where did you learn singing from?

Me: Sir, I’m from a musical background. My father is a classical singer and he has performed at various places. He’s been teaching me music since childhood.

P2: Okay then sing a song.

(I was like, what is happening??? Is it a technical interview or what???)

Me: Sir which song?

P2: Whatever you like.

( I asked for water as I was feeling thirsty)

( Then I sang “Afreen Afreen” song, they liked it)

P2: Have you listened to the original version?

Me: Yes Sir, by Nusrat Fateh Ali Khan.

P2: Good. OK we’re done here, you can go now. You can take eclairs if you want.

(I took two eclairs)

P2: Carefully, it’s not good for your throat.

(We both smiled at each other)

Then i took my documents from the table and came out.

As i was putting my folder inside the bag and leaving, the professor P2 came running behind me. I accidentally took attendance sheet along with my documents. 

I apologized for my mistake, to which he said “You got the attendance sheet carried away with your singing, including us.” I felt amazing.

The professors were extremely down-to-earth and supporting. They were constantly smiling so that we don’t undergo a nervous break down. It was the best interview experience till now in my life. I had a feeling that I will be selected.

I came out and instantly messaged my friend asking about question regarding bijective function. He also said n! to which I felt relaxed.

But when I came back home, I started thinking about moments during my interview where I made mistakes and my mind started to emphasize on those mistakes. Then I thought that professors were good not only with me, but with others too. I started believing that my interview was not extremely outstanding and also intakes from MS are low, so I started making up my mind for the worst case scenario.

18th June, 2019

My friend, Anuj, called me saying that someone has posted on the group that results for the interview are declared.

I checked the portal, and after a while, i got the offer letter.

I was in.

I am grateful to everyone who helped me in achieving this –  my parents, my friend Anuj, all the seniors, who supported me, gave me suggestions and clear my doubts. I know I have done hard work, but I also needed the kind of support which I got from these people.

I’m going to accomplish my dream of studying in one of the finest institutes of India.

Background Yash Kumar Singhal Gate Score 596  CS

Interview Expierence : IIT Jodhpur Mtech Artificial Intelligence

Category : Self Sponsored Category 

Shortlisting Criteria CGPA > 7

I realized there was no interview Testimonial for IIT Jodhpur , so posting this for future Aspirants 

PS They usually ask do you know some AI/ML beforehand . If you tell that you know it , they would ask some moderate ML questions , so its advisable to choose this route if you have some knowledge . My expierence might differ with other since i told them that I know concepts , otherwise they will grill you on your Linear Algebra Concepts 

Questions are as Follows

Q1 ) What is Bias Variance Trade off , explain in Detail

Q2) What are various stragies you can employ to improve Underfitting 

Q3) Concept of Cosine Similarity in NLP and its applications 

Q4) What are some Various Unsupervised Algorithm ? What IS DBSCAN Algorithm

Q5) Geometrical interpretation of Cross Product and Dot Product 

Q6) Write Merge Sort Algorithm , code in shared google Doc 

Q7) What is Curse of Dimensionality 

The interview I though Went decently well

Result 100+ Students applied out of which 8 were selected including me :)

PS I wasnt shortlisted for the IIT Jodhpur Fellowship because it closed around 602 For general Interviews

Once Again I want to thank Arjun Sir and @Bikram Bhalav sir for Gate overflow Community for the constant support and doubt clearing..My Gate 2020 Didnt went well and scored lower than my 2019 Score, however I am glad that I never stopped studying and Tried to get whatever chances I can get 

                   IIT Delhi interview was held on 18^th and 19^th May. Mine was on 18^th. I think around 300 people were invited for it. This year they have given 70% weightage to GATE score and 30% weightage to Interview. Interview panel consist of 2 professors and generally interview went on for 15-20min. So for me the professors in panel were Saroj Kaushik mam and one sir were there but I dont know their name, but I am 100% sure that the mam was Saroj Kaushik. So I will share the conversation that went between us.

Prof :- What is you favorite subject?

Me :- Data structure and Algorithm

Prof :- What is Binary search tree ?

Me :- Explained

Prof :- How will u check whether the tree is a BST ?

Me :- (Thought for a while) We will do inorder traversal and if it is sorted that means the given tree is BST.

Prof :- Complexity of inorder traversal ?

Me :- O(n)

Prof :- Write Structure for binary tree

Me :- I wrote it

Prof :- Now write for generalized tree ( Generalized tree means a tree having max degree n )

Me :- I wrote it.. Basically I wrote array of pointer instead of two pointers in case of binary tree.

Prof :- But your implementation will cause memory wastage because not every node will have n children that means you will have to store null in the array in that case, which will cause memory wastage.

Me :- ( Thought for 5min ) Sir we can use concept of adjacency list. Basically converting generalized tree to Binary tree.

Prof :- Explain the process to convert generalized tree to Binary tree

Me :- Explained

Prof :- Complexity of Binary search

Me :- O(logn)

But they told me that I should also tell it with base 2.

Prof :- Difference between binary search and ternary search ?

Me :- Explained

Prof :- What is the complexity of ternary search ?

Me :- (This time) O(logn) with base 3.

Prof :- which is bigger logn with base 2 or logn with base 3

Me :- logn with base 2

Prof :- Then why we prefer binary search over ternary search ?

Me :- ( was not able to answer )

Prof :- write recurrence relation for binary search and ternary search.

Me :- I wrote it

Prof :- Now find the complexity using those recurrence relation

Me :- while finding the complexity I found out that for ternary search time complexity was O(2logn) with base 3 and for binary search it is O(logn) with base 2. So after comparing these 2 you will find out that complexity of ternary search is greater than binary search.

Prof :- Draw an example of heap tree fast

Me :- (puzzled, how can they ask such an easy question) I drew the tree.

Prof :- Ok you are done

Me :- (I was happy that it went well)

So what I learnt from this interview was that they give some hint if we stuck somewhere. For me I was stuck on comparison between binary and ternary search, So they told me to write there recurrence relation and then evaluate it.

Verdict :- Selected :) 

Hello Everyone !!!

The written exam happened on 12th Jan 2020 and the shortlist for the interview came on 9th May 2020. I was not much confident about the ISRO examination result but I got shortlisted for the interview.

Interview Experience :

Date of interview-  10th – March -2021 

Venue- NRSC Guest House Conference Hall, Balanagar, Hyderabad.

Time- 8:30 AM.

In the big reception hall, everyone was asked to sit and wait for their turn. At appx. 8:30 AM, they verified the documents and covid report. Document verification was done. At 8:45 am they called me inside of another waiting room. I was waiting outside of interview hall.

My interview was started at approx 9:00 am :

As I entered the room there was a big table with big screen, and panel head (PH) was on the screen. then panel head asked me to sit. 

PH : (smiling) Devendhar right….?

Me : Yes sir

PH:  You from Hyderabad (Telangana) ?

Me: Yes sir

PH:  How are you? and is everything fine ?

Me : Im fine sir, thank you.

PH: How is the covid situation in your town?

Me: Now situtation is improving in my town sir and day by day becoming normal.

PH: I hope you and your family is safe ?

Me:  yes sir, thank you.

PH: okay. Tell me about your academic background ?

Me: Introduced myself.

PH: Which programming languages you are comfortable?

Me: C, Java

PH: What is OOPs?

Me: Answered

PH: What is Polymorphism ?

Me: Answered

PH: What is overloading and overriding ?

Me: Answered (but could not defined in proper way)

Then he asked one of the panel members to continue…

P1 :  what are your favourite subjects ?

Me: Data structures, Algorithms, Database and management system, Operating system.

P1: What are the functions of OS?

Me: Answered

P1: What are IPC Mechanisms?

Me: Answered (I mentioned only few)

P1: Any other IPC mechanisms  than what you told ?

Me: Answered

P1: What are various process states ?

P1: What is pre-emption?

P1: What are synchronization mechanisms ?

I answered all of them, then he moved to C

P1: What is Declaration and Definition of a variable? difference between them ?

P1: What is Postfix and Prefix?

P1: What is Structure and Union? Difference ?

I answered all of them, then he moved to Computer Networks

P1: LAN vs WAN ?

P1: What is Ethernet ?

P1: What is CSMA/CD and explain in detail?

P1: What is firewall and Why we use it?

P1: What is Denial of service attack ?

I answered and all of them, then he moved to Software Engineering

P1: What is SDLC and what are the phases ?

Me: I gave definition, bt he asked me explanation of each phase. Then I explained the each phase.

P1: What is whitebox testing and blackbox testing ?

Me: First, I gave definitions bt bt he asked me to explain. I explained.

Then he asked one of the panel members to continue…

P2:  Are you comfortable with compiler ?

Me: yes ma’am (with doubtful face bcz I didnt mentioned in fav subjects)

P2: Why compiler ?

P2: What are the steps in designing the compiler?

P2: What is interpreter and compiler? differences?

Me: Answered all

P2: Is compiler platform dependent ?

Me: I said yes

P2: If I compiled one program in one machine and can I run it on another machine or Do I need to compile again?

Me: Yes ma’am, need to compile again

P2: are you sure ?

Me: Yes ma’am

P2: really ?? 

Me: We can use cross compiler also ma’am.

P2: Ok… I’m done with you.

Then Panel head asked one of the panel members to continue…

P3: you did project in Deep learning right ??

Me: Yes, ma’am

P3: What is neural networks ?

P3: What are different types of neural network connections ?

P3: Different types of learning algorithms?

P3: Which one is used in your project ?

P3: What is the benifit of Reinforcement learning ?

P3: What is Activation function ?

I answered all of them

P3: How you say it converges and when you stop ?

Me: answered (but could not explain in proper way)

Then the Panel head said that we are done with your interview and asked me to leave.

My interview lasted for around 30 – 35 minutes.

Result : Selected

I would like to wish all the best to ISRO and GATE aspirants.

I would like to thank GATEOVERFLOW specially Arjun Suresh sir, Bikram Ballav sir and all others who are working to guide computer science students.

Thank you