ISI Kolkata Previous years Interview experiences :

**Subjects to emphasize –> ( DS, Algo ,TOC, NETWORK,DBMS, OS ,DISCRETE & ENGG MATH )**

They are asking from any topic very easy but conceptual questions.If we cannot answer properly,they are giving a lot of hints.

**Interview 1 :**

It went for about 1 hr 10 mins. i was asked questions from equations, number theory, etc. then i was asked about cse subjects. i said toc, they asked for something else , i said algo. they asked me to find efficient sorting algorithms given some situation. then they asked about which sorting algos to use given a particular situation. to find complexities from recurrence relations and all, np-completeness.

**Interview 2 :**

My interview went for about 30 minutes or more…

Questions were on mathematical puzzles, Functions and Continuity, Algorithm, Calculus (Sequences)….

I had to give a detail description on Sorting…right from Decision trees to complexities and so on.

They asked me totally on Math. Number of onto functions from a 6 element set to a 2 element set without using formula for onto functions,condition for onto functions,a determinant problem,simple class 6th standard geometry(which i cant solve and they were laughing seeing that i have forgotten this),no of multiplications in expansion of a n*n determinant problem and one good question print largest 10 elements of a binary search tree in most efficient time.But profs are cool,they are helping 90%.That’s all.

**Interview 3 :**

i was also asked to provide details of sorting algos with proofs of complexities in more than one way.

the questions were not easy but they were very basic.they asked me questions from maths(probability and permutation),DS, Automata.

**Interview****4**:

I think one can solve at least 10-12 questions from Objective math if he/she has good basis of fundamental discrete and real mathematics. In subjective paper, mathematics problems were tricky, I solved only one…. but at least three from CS were normal ( semaphore, networks and automata ).

1. a) Let you have a program P that can compute median in O(n). Use P to design an sorting algo that can sort in O(nlogn)

b) You have an uni-modal sequence (Definition was given in question, search net for definition). Find the mode in O(log n).

2. There is a forest where there are tigers and elephants. There are two processes named tiger and elephant. Design a concurrency processing using semaphore, such that tigers and elephants can not drink water from a pond simultaneously, whereas more than one tiger or more than one elephants can drink water simultaneously.

3. Z scan of a matrix, if a 2×2 matrix, then print elements like ‘Z’, i.e. (0,0),(0,1),(1,0),(11). If 4×4 matrix, then divide it into four 2×2 matrix in form of ‘Z’, scan each of them again in forms of ‘Z’. [diagram was given]. Write a C function to implement this for NxN , where N=2^m.

4. Networking, IP address and ethernet

5. Database- recovery of concurrent process failure, 3NF and 2NF decomposition

6. a) Show that the language W that consists equal numbers of ’01’ and ’10’ as a substring, is regular.

b) A grammar was given. Show then it is ambiguous, then remove ambiguity from grammar to produce an equivalent grammar.

There were two more questions from algorithm design and parallel processing .

*Tips:*

General category rank cutoff at ISI kolkata , last year(2010) was approx 800. Not very sure though.

Placements : min 4lpa(IBM) , avg 8lpa , max 18lpa(IBM IRL).

Recruiters : Google,NVIDIA,IBM Research,Opera, LoudCloud etc.

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