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hey guys,i have just written a post(or tried to write :D) on my IITM experience

REad it here

https://uddiptab.wordpress.com/blog/

The process of selection for interview at BARC is first we have to qualify the written test conducted by BARC or we can also qualify by GATE score released by BARC. I qualified BARC written test as my GATE score was not that good. Total 98 students were selected for interview for Computer Science and I was one of them.

BARC TS Online Examination Score Cutoff :160.00(This varies every year).( My score was 183.60.The gate score cutoff was 880).

Although, I heard that in 2018 it was 130 (BARC TS Online Examination Score Cutoff ).100 students were called for interview, out of that, 8 students were finally selected for this program ( 700/1000 was my Interview Score where as Interview cut-off was 650).

After that we were given choices to select interview slot. I chose the one on 12th June in afternoon session. I reached BARC centre on 11th June and requested for the guest house which I got (During the interview, the weather ,the view of Anushakti Nagar was awesome, I was flattered (as I am from UP :):). On 12th June we had to reach the interview venue which was next to the guest house. So, I reached the auditorium 5 min before and got my documents verified, and then I was informed that my queue number is 9 and would have to wait for my chance.

My interview started at 03:12 pm and went on till 04:13 pm.

When I entered the room, there were 7 interviewers sitting along a semicircle.

I will denote the interviewers as I1,I2,I3,..,I7  from my left to the right in clockwise direction.

I greeted all of them and they offered me to sit. Then I4 asked me that you don't have your marksheet of 3rd and 4th year why?

I explained (They laughed, I don't know why?).

Then directly I4 asked me to write some 4-5 subjects I'm confident in, on the blank sheets. I wrote Compiler, Data Structure and C Programming, Algorithms, Operating System. Then they said that they were OK  with these subjects.

He asked I7 to start with Compiler. The interviewer didn't ask me direct questions. He started confusing me right from the beginning.

I will try to explain what he actually wanted to ask instead of confusing you all.

Compiler:

How to make a tree for any given expression(working of syntax analyzer)?

In how many ways can we represent an intermediate code, explain with an example?

During the construction of DAG how do we manage to maintain the partially made DAG to check repetition. (Which data structure do we use and how do we maintain it) I was very confused as they were adding there conditions as i replied anything.

What is a hash table how does it works?

Given a language write regular expression, make dfa, and what is the main difference between its dfa and nfa.?

Why do we make nfa, if dfa is easy to make?

How do we use dfa to maintain lexical analyzer( how does lexical analyzer use dfa to track lexemes)

Then I4 interviewer told I1 to move to OS part.

OS:

What is the difference between various types of operating system?

What is the difference between hard real and soft real type of operating system? Why do we use the term hard real time and soft real time operating system.?and it's application.

What is virtual memory?

Given a scenario to design your own operating system which features do you think is necessary for your operating system and why?

(And many more confusing ques not direct so I didn't recall much).

Then I4 told I5 to move to Algorithms.

DSA:

How and why does merge sort works?.

What is the difference between various sorting algorithms and why should we prefer one over the other explain for each sorting algorithm.

Write recurrence relation for merge sort and solve it.

Write a code snippet to delete a given binary tree completely.

Write a code snippet to check two binary trees are same or not.

After this I4 interviewer himself started with C programming.

C Programming:

Can we pass parameter to main function?

How does command line argument works? He told me write code to explain in detail.

Why do we put address in the scanf function? And why not in printf?

What is call by value and call by reference?

After all of this, the I4 interviewer told me that the interview is done and i can leave. It was a one hour long interview but i think they were in hurry as i was the last person for this panel of interview.

I tried to remember as much as possible but there were some more questions.

There were situations that i was trying to explain they said that if i don't know then its OK but i keep on requesting to let me explain they use to laugh and give me time.

I was feeling very proud to be interviewed by these panel and even for reaching there to get interviewed.

And on 27th June, the result was out. There were 8 students who were selected and I was one of them. :)

Feel free to ask your queries.

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.

My ISRO interview was scheduled on 30th July 2018. I had joined IIT Bombay just two weeks before. Studies have started(even though not in full momentum). This interview meant a lot to me. So I prepared daily for 1–2 hours for the interview. I submitted the weekly assignments on friday and left for Delhi by train on the same night.

I reached the interview centre and found out that my number was in the end of interview list. I became worried as I had my flight at 9PM. I told them about this and they told me that they were rearrange my number. My interview began at about 4:30 in the evening. I went inside the interview room and found 9 interviewers(1 in the middle, 4 on each side). They first asked me about my favourite subjects and I replied Data structures, Networks and OS. Then the following questions were asked:

• What were the algorithms that you used in your project
• Explain the working of Random Forest?
• Is Database a system or Application program( No where related to my favorite subjects)

I answered the first two questions satisfactorily but for the 3rd questions I replied application program and the interviewer(let’s call him X) looked disappointed. He immediately asked the interviewer beside him(Y) to ask the next questions. Y asked 3–4 questions from OS( which I don’ remember now). I answered them. He was satisfied and then he asked X to ask the next questions.

• What is a tree?
• Difference between a tree and Forest?
• If u are given 7 nodes how many trees and forest are there?
• What is BIOS?
• What is firmware?
• What is VLAN?

I explained the first 4 comfortably. For firmware he accepted the definition but not satisfied much. For the last question I told him the full form. Then I said I don’t about its working but I told him whatever I can guess from its name(It was a good guess). He started laughing from my explanation. Then he again asked Y to ask questions. Y again asked some questions from operating system like

• How deadlocks can occur
• How can you prevent them
• What is a semaphore and its operations
• What is priority inversion
• Context switching

I answered all these questions satisfactorily. Then another interview who was sitting to the left of head started asking questions

• What is mutation testing?

didn’t know

• What is regression testing?

Explained?

• write code to find gcd of two numbers using Euclidean algorithm?

I had forgotten this algorithm. So I went to the whiteboard and stood there for 2 seconds and then wrote the algorithm. Then I looked towards the interviewers and they said OK

• Now Y asked in the code that you have written which among a,b,r is the gcd?

Big problem. I knew that r is not the gcd but confused between a and b. I just stood there for 2–3 seconds and then I gave an interesting explanation. My code was

while(r!=0)

{

r=a%b

a=b

b=r

}

I told them that this loop is going to stop when r becomes equal to 0. Now suppose that the loop stops in the nth iteration then in the (n-1)th iteration the value stored in b would be the value of r(which means 0). Now since gcd of two numbers cannot be 0 therefore r and b are eliminated and hence a is the gcd.

At this point for the first time X and Y both were smiling. Now the head started asking questions from Computer architecture

• What is programmed I/O?
• What is interrupt I/O?
• why interrupt I/O is better than programmed I/O?
• what is daisy chaining?

I answered all of them. After I have gave the definition of daisy chaining they wanted me to tell more about it. I didn’t remember any. At this point X helped me and then I told them about priorities in daisy chaining. At this point again I felt positiveness in the interview room. There were two ladies sitting in among them and both were silent upto this point. The first one asked

• what is optimum page size and how do you decide where a page size is good or bad?

Explained

• What is the difference between for loop and while loop( I mean they were asking which is more powerful)?

I said no difference.

• Then why these two are provided. why not only one?

I told that even though both are equally powerful sometimes the condition can be more naturally expressed by while and sometimes by for.

• X asked me to go to the whiteboard write the program that I have already written but using for loop

I did that and all were satisfied. Now the 2nd lady asked something about memory management. I asked thrice to repeat the question or explain it more but I was unable to interpret what she was asking. In the end I gave a half hearted answer. Then she asked

• How is multiplication done in computers?

I told her Booth Algorithm. Then I was told that the interview was over.

Some tips for ISRO interview:

• I felt that they check the breadth of knowledge and not depth
• You can use Hindi as well as English during the interview. I initially started in English but got stuck at some point and asked them if I could use Hindi. They said of course. Now during the later part of interview for a few questions they asked me to explain in English. I felt that they were trying to test me and then I gave the answers in English
• Don’t worry if your interview starts badly. Mine started in a bad way but it ended on high note.
• Even if you don’t know the exact answer to the question don’t just say I don’t know. Instead tell them you don’t know completely but you have some idea(if you really do) and then try to explain that idea. Happened to me in that VLAN question. However if you don’t have the slightest idea then just plainly say that you don’t know
• Your presence of mind can help you a lot.

Interview result: Rank 2 in the merit list

81.38 scored out of 100.

Best of luck to future candidates.

Thank you.

I- Interviewer, M- Me

I- What are your favorite subjects?

M- Linear Algebra, Probability, DS/Algo.

I- Given a matrix $A^2$=0, what can you infer from this?

M- A is nilpotent matrix, eigen values are zero.

I- What about determinant of A?

M- $A^2$=0 =>$|A|^2$=0 =>2*|A|=0 =>|A|=0

I- What about $A^{-1}$?

M- won’t exist.

I- How do  you define inverse?

M- A matrix when multiplied by original matrix produces identity matrix is inverse.

I- Can you prove inverse won’t exist without using any of determinant things (I guess he didn’t wanted to hear things like |A|=0, so inverse won’t exist)

M- Sir assume $A^{-1}$ exists.

$A^2$=0

$A^{-1}$$A^2$=$A^{-1}$0

($A^{-1}$A)A=0

A=0

so even if assumed $A^{-1}$ exists in that case, A has to be null matrix but even the inverse of null matrix doesn’t exist because any matrix multiplied by null matrix produces null matrix always and never an identity matrix, so A can’t have inverse in all cases.

I- What’s volume of a n-dimensional cube?

M- couldn’t answer.

I- In 3D, suppose $0\leq x \leq 1$, $0\leq y \leq 1$, $0\leq z \leq 1$and $x \leq y \leq z$, what will be the volume enclosed by the set of points?

M- couldn’t answer.

I- Let’s simplify for understanding purpose, In 2D, suppose $0\leq x \leq 1$, $0\leq y \leq 1$ and $x \leq y$, how’ll the set of points look like?

M- Area of triangle with vertex as (0,0), (1,0), (1,1).

I- What’s it’s area?

M- ½

I- Now come back to the 3D problem I asked, how’ll the shape look like?

M- Tetrahedron.

I- How will you approach to find the volume?

M- will use calculus and find a small enclosed volume then integrate over it.

I- Obviously calculus can be used but we’re talking about linear algebra, so tell me something in that regard?

M- still thinking so then he moved to the next question.

I- Suppose we’ve set of functions with domain {1….m} and range {1….n} (considering only integers in the intervals), suppose you’ve two functions f(x) and g(x), what is the expected number of values in domain for which f(x)=g(x)?

M- thinking….(interviewer starting to simplify)

I- Tell me the probability of f(x) (or g(x)) taking any one value from range, more precisely probability that f(x)=1?

M- 1/n

I- So probability that f(1)=g(1)=1?

M- 1/$n^2$

( can think of it as prob{f(1)=1&&g(1)=1}= prob{f(1)=1}*prob{g(1)=1}     ::Since f(x) and g(x) are independent.

                                                               = (1/n)*(1/n)= 1/$n^2$

I- Probability that f(1)=g(1)?

M- $\sum_{x=1}^{n}prob(f(1)=g(1)=x)=\sum_{x=1}^{n}1/n^2=n/n^2=1/n$

I- So now what’s the expected number of values where f(x)=g(x)?

M- m/n

I- How did you do?

M- Told them approximately the below thing but got confused later…

Expected Value= $\sum_{x=1}^{m}prob(f(x)=g(x))$= $\sum_{x=1}^{m}(1/n)=m/n$

Now comes the Algo Question...

I- You’ve an unsorted array of ‘n’ elements, minimum number of comparisons to find the second minimum element?

M- 2(n-1)

I- Are you sure, I can tell you that there is much more smaller value possible, let me give you an hint, consider ‘n’ teams playing against each other, how’ll you find the winner and the second winner?

M- We’ll first compare pairs of elements and choose the minimum and then compare the next set of minimum and so on until we find the last minimum element.

Number of comparisons = $\frac{n}{2}+\frac{n}{4}+\frac{n}{8}.........+\frac{n}{n}$

                                       = n-$\frac{1}{2}$

(did wrong calculation during the interview.)

I- How’ll you find the next minimum?

M- The next minimum would be the element that was last compared with the minimum element.

I- Consider the sorted array 1,2,3,4,5,6,7,8 what would you say now?

M- Yes, sir it won’t work that way.

I- Try to relate with the analogy of the teams playing matches?

M- The second minimum would’ve definitely lost against the first minimum at some point, so we can keep track of the entire path for the winner starting from first comparison to last and can find the second minimum in this path itself.

(Interviewers weren’t much satisfied it seemed, I guess they were hinting towards the tournament tree algo which I didn’t remembered that time.)

I- Why did you moved from Mechanical to CSE stream after first year?

M- Sir, I started to develop quite a bit of interest in coding in my 2nd sem and seniors and everyone used to say about the job scopes and ever growing opportunities in CS. So all these biased my mind with entering into CS.

I- Are you satisfied with your decision about jobs and all?

M- Sure sir, but recently I’ve started to develop more interests in research than jobs, in fact I didn’t go to placements in my college and prepared for entrance exams instead.

I- Why so much interest in research?

M- It came out of my research internship at ISI Kolkata last year, I did comparative analysis of corporate jobs and research life and found the later to be more exciting and learning new and creative things everyday on the way while corporate job seems to me like doing more or less the same thing everyday.

I- What all entrance exams you gave?

M- TIFR, GATE and JEST.

I- You can leave now, we’ll contact you later if something required.

(P.S.:- It might be possible that my answers written to above questions are wrong at many places, but the questions are very close to what I could remember. Overall TIFR being very good at Theoretical Computer Science research seemed to be much more focused on mathematics at depth. At TIFR, CS is only there at Mumbai Campus as of now.)

Hello everyone,

I’m Arunjyoti, one of the shortlisted candidates for BARC-OCES 2023.

I cleared the written test and appeared for interview at BARC, Mumbai.

Interview:

The interview panel consisted of 6 members.

Interview started with my introduction and after that they asked me to write down subjects that I am prepared of.

I wrote Data Structures, Algorithms, C++, OS, DBMS.

I have briefly listed down the topics that were asked during the interview. (I1 => Interviewer 1)

I1 (DSA) :

Representations of Graph, told to write code for the same on paper(No STL), Topological ordering, cycle finding in graph.

I2(OS)

Basics of Process and Thread, Process creation, Virtual memory, linking etc.

I3(DBMS)

Told to design one ER Model for given scenario, SQL query, Joins, Normalize  the db, Examples of one to one , many to one etc mappings, Isolation levels, how isolation is achieved etc.

I4(C++ & Software Engg.)

Asked about OOPS, access specifiers, Macros and their benefit, Types of software testing etc.

I5

Asked about fixed point representation and some discussion about the same.

I6

Asked about types of cache, then discussion went into cache coherence problem and solutions.

After that interview ended. It was around 1 hour and 15 minutes.

Overall it was a nice experience. The interviewers were very helpful and supporting.

A big thanks to GO community. 😊

Result : Selected

IIT Madras MS (CSE) Interview

Date: 20-07-2020

Online Interview (Google Meet)

There are 5 interviewers in panel

Prof1 : (smiling) Devendhar right….?

Me : Yes sir

Prof1:  You from Telangana ?

Me: Yes sir

Prof1:  How are you? and is everything fine ?

Me : Im fine sir, thank you.

Prof1: How is the covid situation in your town?

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

Prof1: I hope you and your family is safe ?

Me:  yes sir, thank you.

Prof1: Asked me Introduction

Me: Introduced Myself

Prof2: Programming question

Given a 2d matrix which contains 0's and 1's only, is there any row contains all 1's ? 

They gave me a link of notepad and said me to write code in it.

Me :  I wrote

Prof2: Okay, Done with you.

Prof3: Which subject you chose ? (they gave me a link before the interview to choose the primary subject)

Me: OS sir

Prof3: What are the different scheduling algorithms?

Prof3: What is the pre-emptive scheduling algo?

Prof3: Given a problem (AT, BT), find avg TAT, WT using Round robin algo?

Prof3: What means TAT?

Prof3: How to choose appropriate Time quantum ?

I answered all of them 

Result : Selected

After 6 months of preparation of gate along with my software development job . I was screwed in my gate exam( venn diagram question of 2 marks, of which I found out correct answer but I don't know how other option got ticked which I came to know after seeing response sheet and also I missed the question to find out 2s compliment as when I reached that it was just 20 secs remaining) the paper was very easy hence I slipped my rank and landed on 1454 rank and I know iit was only a dream now. That 3 4 marks silly mistakes costed me my iit dream.

Then there was iiith pgee exam a month later. seriously , i didn't prepared for it(because workload was too high as I took 1 month leave already for gate). Still I was able to clear the written and reason I think was the aptitude section. I had prepared for cat in my bachelor's so the quant and english was a cakewalk for me and technical section was also too easy as compared to gate.The thing here is you have to clear both sections aptitude and technical to be called for interview.Hence prepare for aptitude and english too if you are not strong in that.

Now as I know the date of interview was 13 June I resigned my job and got free till end of may and had around 10-11 days for interview preparation.

First I started reading previous year interview experinces from pgee fb group and response sheets of previous year and made a list of topics subject wise from which questions were asked and then allocated a day for each subject.Following is the list

1)C and DS - array heap tree fib heap,c struct pointers , Avl Red black tree,print all elem in Bt with no siblings  -monday

2)Algorithm-algo bfs dfs, sorting ,dynamic prog / divide n conquer,branch and bound knapsack, tree forest,prim krushkal ,dag dijkstra - Tuesday

3)OS- os process execution link load first fit best fit semaphonre -  Wednesday

4)DBMS-dbms lock  primary foreign keys fd,normalization - Thursday

5)Discrete -maths divide rules,  sets relation fnction, vectors,matrix, rank inverse ,determ, 0 eigen values,mead median mode- Friday

6)network &Probab -probab coins and names question and dictionary, bayes theorem mutually exclusive events- Saturday

7)Graph Theory- graph for functions ,paths sets , independent set, edge cover, vertex cover- Sunday

8)Miscellaneous-mails from and without browser,network,tcp ip, functioning when we search google.com ,network 127.0.0.1

lines ,circle, eqation graphs of functions , toghest code written, last sem subjects . Monday

I first revised the subject in whole day and then the topics which are asked again in night. Now in this way I covered almost all topics till 10 .on 11th I read miscellaneous things and had reservation from pune to Hyderabad(which was rac so I was hell lot tired as I was not able to sleep in whole night journey).

I already had friends in Hyderabad but the thing I did was booked a hotel for 12th to 13 as I already stayed with my friend during interview of iitb and iisc and we just talked till 2 in night as we met after a long long time, so I decided to book a hotel for a day before interview(got an ac room in 260 rs courtesy Oyo ) and then stayed with my friends after interview for 3 4 days and visited Hyderabad too.

The Day before Interview- I reached my hotel my sharing an auto from railway station to iiith . Then I checked in and had lunch and slept 3 4 hours in afternoon .Then i studied in hotel room , revised short notes till 1 and went to sleep . 

The D Day- I woke up at 7 , took bath and went for interview There I had breakfast in college itself. There first verification was done and then called according to some sequence in 4 panels . I was 7th in 3rd panel and there were around 30 candidates in each panel.

I was calm and confident. I went in room there were 5 interviewers. They took my resume and asked about my work experience. I had 1.2 yrs of front end development in amdocs . Then they asked what you did from July2017 to march 2018 . I said our joinings were late so we just enjoyed. They asked how I was placed. I said campus placement.

Now came the turning point . The third interviewer asked me about difference of JavaScript and java . I didn't came with a strong answer. Then they asked me about why js is used in Front end. I said it is evolving and new Frameworks are continuously coming but seems he was not satisfied with my answer(I later searched and found out that js is not compiled. It is executed directly and a script)

Now the 2nd interviewer asked me my favorite subjects . I said algo data structures. He asked how many data structures I know . I said tree graph , trie, array , stack queue etc. He asked whether you know about hashing. I said I don't know much in dept about hashing but you can ask me about linked list and algorithms.

Till this time I thought I had screwed a lot but still I carried out. He asked me to find the nth element from end of single link list .I already knew it and told. Then if link list is doubly , no of steps taken to find kth step from end(n-k +2k). Now he asked how can we find a pair of number that sum to a specific value in array. I said one is brute force other is by sorting. He then gave me chalk and told to write full code line by line of brute force which I did. There were some silly mistakes like i=0 to i=n which they all laughed. He asked me another approach , i told we can sort array and start with checking sum if extremes to the given value. then he interrupted as he thought I knew which I did.

Now again 2nd interviewer gave me pen and paper and asked me to draw graph of logx and x =y. I drawed it incorrectly so he told me to check if it's correct. I had made log 0 =0 . But then I corrected and told that i was a little nervous. He told me to chill and again asked to draw the graph of log x to the base 2 log x to the base 3 and difference between them .

Then they told me I can leave and take choclate. I asked it was done and they said yes. I told it was great meeting and talking with you and they said same.

Later I went charminar enjoyed biryani and stayed 3 4 days with my friends in Hyderabad and came home.

Seriously I had not much hope as other people might have given their best and I was not able to differentiate between java and JavaScript. I was just ready to go to nitk for admission on 20 and on 18 result came and I was selected for mtech cse in iiith. It was really a dream come true . I cannot just control my happiness and emotions. I told my parents and friend and went to temple to pray and offer prashad .

For pgee you should prepare aptitude english and maths as it is compulsory to clear it's cutoff rest you will clear if you studied properly for gate . Now coming to interview just go through previous interview experinces . Revise all major subjects and then the topics which have been asked previously.

My advice to aspirants of gate and pgee is sometimes things go wrong but keep trying. Hard work always pays off.

IIT, Jodhpur GATE Overflow Interview Experience List: 2020

Subject of choice: Data Structures

Questions:

1. What is a BST?
2. How will you traverse it?
3. What is topological sorting?
4. Where can you observe topological sorting in real life?
5. Which BST traversal algorithm will give you exact/close approximation to topological sort?
6. How will you modify the traversal algorithm to approximate topological sort? ( Couldn’t ans this well)
7. Suppose you have an acyclic graph and there are two nodes which do now have an edge between them does swapping the two nodes have an effect on correctness of topological ordering?

Programming: WAP to find max element in linked list. 

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

Interview date: 23-07-2020

Round 1(written): Wasn’t conducted due to ongoing pandemic.

Round 2(Interview): duration of the interview was about 1 hour.

I was told that they will first ask some programming questions and then move to subjects which I was asked to select before the interview. The subjects were Data Structures and Database Systems.

Programming:

I: Write a program to find the largest element in a linked list?

M: They told to check some conditions. Initially, in line number 9, I wrote some mistake which I corrected later. 

#include<bits/stdc++.h>
using namespace std;
int findMax(struct node *ptr){
    if(ptr == NULL)
        return -1;
    if(ptr->next == NULL)
        return ptr->data;
    int mx = ptr->data;    
    while(ptr != NULL){
        if(mx < ptr->data)
            mx = ptr->data;
        ptr = ptr->next;
    }    
    return mx;
}
int main(){
    //assume linked list is given.
    cout << findMax(struct node * start);
    return 0;
}  

I: What is full Binary Tree?

M: Got confused with Complete Binary Tree(CBT). I told them a binary tree which is left filled and then changed my answer to a binary tree having all the leaves at the same level. But, they told that a tree in which all internal nodes have 2 children.

Data Structures:

I: Determine a logic or code to determine if a tree if full binary tree or not?

M: We can make a recursive call to the left and right subtree and for each node check if both left and right child is not null. When both the children are null means the terminating condition is reached and it is a full binary tree. Then I wrote a pseudo code.

I: Can you determine the recurrence relation and determine the time complexity?

M: I got a bit confused and told O(logn) thinking of BST. Then they helped with an example and wrote the recurrence relation as

T(n) = 2 * T(n/2) + c

Then applied the master's theorem

a = 2, b = 2, k = 0, p = 0
O(n)

 I: If some relative order is given in an unsorted array, how many comparisons are required? He told I am just asking you for the challenge you can think and search after the interview.

M: I told about topological sort and can apply DFS. I also discussed Tournament tree and comparison should be required O(n). But he told you are in the right direction but in this short span, it will difficult to take in the full solution. Have a look after the interview.  

Database Systems:

I: Do you know Durability?

M: It is one of the ACID properties. It shows that data in the system remain persistent.

I: How you achieve it. Please be technical.

M: Through creating logs.

I: Do you know the types of logs?

M: I did study but could not recall the types.

I: Why you need and how you achieve durability, consistency, etc.?

M: Check over system failure, local error, disk failure, etc. Periodical checks can be performed.

I: Write a Relational algebra to determine the names of the employee working under the supervision of supervisor ‘Smith’?

M: Pi(names)(Sigma(E1.sid = E2.eid and E2.name = ‘Smith’)(E1xE2)). We could have also used joins.

I: In DBMS whose responsibility to determine the consistency?

M: It is the responsibility of the database system to check the consistency.

I: Who is responsible for Isolation? 

M: Database Manager so that interleaved execution can be omitted.

I: Any questions?

M: If selected how the labs will be allotted (AIDB, RISE labs)?

I: After selection, you will be asked your choice and depending on the professor. Any more question?

M: No. 

I: You can leave the meeting and thank you.

M: Thank you, sir.

There were 6 professors in the panel.  The total duration was around 20 minutes. Interview held on 1st June 2023.

My gate rank is 983 and my score is 626 general.

P1 – Introduce yourself.

Me- Gave my introduction

P3 – Tell us about your Project.

Me – Answered

P2- Tell us more about it

Me- Explained the features and type of problem(It was a classification problem)

P4- What are the algorithms you used

Me- Discussed Naive Bayes,  KNN, Logistic Regression, Random Forest, SVM for classification

P4-How you select the best algorithm?

Me- Explained Log loss correctly. I told them, logistic regression is performing better in terms of log loss

P4 – Write Logistic Regression Equation on board

Me- Wrote the Cost function equation and sigmoid equation.

P4- Explain how Logistic Regression works.

Me- Trying to explain taking Gradient Descent into consideration

P5- We are landing on different islands(He meant that they were not able to connect the dots)

Me- Drew a graph of gradient descent(convex function) and tried to explain but they were not satisfied

P6- Okay now tell me what you want to do in Research work

Me- Something related to NLP

P1- What is NLP

Me- Natural Language Processing

P5- Are you interested in Climate Study?

Me- said no but not directly

P6-Do you know Python

Me-Yes but I haven't practiced much since I was preparing for GATE

P4- So in what area do you want to work?

Me- In the health sector, genetics variation, predicting diseases, and automation of testing processes.

P6- Do you know Statistics

Me- Yes(with confidence)

P6- Tell us about Normal Distribution, and why it is useful

Me- Gave an answer but they were not satisfied

P6- Do you know about kurtosis, skewness, deviation

Me- I don't know about Kurtosis, but I know about skewness and deviation. explained Deviation

P4- Asked many questions related to the normal distribution and Random variable

Me- Answered a few of them. (In between I said “I don't know” more than 4 times)

P6- Are you interested in Statistics

Me – Absolutely

P1- Okay you can go now.

Me- Thank you, everyone

Result: Selected (result came via mail on 23rd June)  

PS: P4 helped me a few times when I was about to say “I don't know”.

Resources you can follow:

-Machine Learning(Andrew Ng) : For detailed learning

-Machine Learning(Krish Naik): https://rb.gy/ovemb (For summary and brushing up)

-Linear Algebra(Gilbert Strang): https://rb.gy/ay1b0

-Probability(John Tsitsiklis): https://ocw.mit.edu/courses/6-041-probabilistic-systems-analysis-and-applied-probability-fall-2010/

Also, go through basic statistics topics like Mean, Median, Mode, Standard Deviation, etc.

Tips: They ask plenty of questions about your project, so prepare it thoroughly. If using some particular algorithms, then make sure you know the maths behind it. Do some research about the professor's work prior to the Interview. Professors are quite helpful when you are stuck, so try to take the hints. Have a positive attitude when you are not able to answer and accept your mistakes when you are wrong.

All the best!

Last time ECIL recruited was in 2012–2013 and I was not able to get any info about the interview procedure. So I decided to write it down to help future aspirants. ECIL GET 2017 written was held on 21st January 2018 nation wide. 40 people were selected for interview against 10 posts.

Location : CLDC ECIL,Nalanda Complex, near TIFR Hyderabad

Time: 8:45 AM onwards

Duration: 30 mins on avg.

Process : 2 round document verification followed by interview.

Interview Experience

The panel consisted of 6 members.Each of them were the master of their own field. Some said they were not from ECIL but from outside. (maybe from BARC, TIFR or IITs).The panel was very humble and friendly. No certificates or resume or cv was needed to be taken to the interview room (certificate verification will be carried out before).

They asked me my name , college where I did my engineering, year of passing. They might even ask few general queries about your home or college placements.

They asked me if I was prepared for the interview to which I replied “only few subjects”. They asked me to write down those subjects and a programing language along with that.

I wrote :

1. CO

2. OS

3. DS

4. C language

Few of the questions as far as I remember.

1. Draw the diagram of the architecture of a computer.
2. What are the speeds of your CPU and Main Memory?
3. How does the computer manage the speed difference between Processor and RAM ?
4. What is a cache memory? Which concept is the reason because of which the cache memory works effectively? How read and write operation occurs in cache memory (Write through and Write Back).
5. What is the size and speed of a cache memory in general?
6. Draw the memory hierarchy diagram and tell us the relative speed of each memory type.
7. Explain how cache memory works in detail ?
8. What is an interrupt? What are the types of Interrupt ? Explain interrupt cycle in detail? Is the interrupt executed after finishing of current cycle or current instruction or current program ? Where is the current states of a process stored when an interrupt occurs?
9. What are the types of Interrupt pins in 8085 microprocessor? What is 5.5, 6.5,7.5 in RST 5.5,RST 6.5 and RST 7.5 ?
10. How many pins are there in 8085 microprocessor. Can you draw them ?
11. What is paging ? Explain it in detail in paper.
12. What is inside a page table? Are all the entries in a page table valid ?
13. What is virtual memory?
14. Explain any process synchronization technique in pen paper. Why there is a need of synchronization? What is a critical section ?
15. Do you know about windows server edition 2015 ? (I answered No and later I found that there is no server edition 2015)
16. What is a stack ? What are the applications of stack ?
17. Which type of program is better, Iterative or Recursive ?
18. Pros and cons of iterative and recursive programming methods.
19. Write a program to find the factorial of a number using recursion? ( Asked me to explain it step by step, they made changes to the program and asked me what will happen to the output etc etc)
20. Draw the activation record diagram of the above program and explain it.
21. How will you know that stack overflow has happened ?
22. How can we know the size of the stack for a program ?
23. Write a program to check a leap year and explain it line by line.
24. Why can’t we use the desktop’s windows 10 on your smartphone?
25. What is a kernel in OS and how does it work?

In the end they asked me how was the interview and I replied “It was a great experience”.

They will ask you “what”,”why”,”how” to every new thing you speak. These were the overall questions. They asked many small questions in between my explanation to other questions.