ISRO CS 2017 December

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Question 1

Consider three CPU intensive processes, which require 10, 20, 30 units and arrive at times 0, 2, 6 respectively. How many context switches are needed if shortest remaining time first is implemented? Context switch at 0 is included but context switch at end is ignored

  • 1

  • 2

  • 3

  • 4

Question 2

A process executes the following code 

for (i = 0; i < n; i++) fork( );

The total number of child processes created are

  • n2

  • 2n+1 -1

  • 2n

  • 2n -1

Question 3

Which of the following is false?

  • User level threads are not scheduled by the kernel

  • Context switching between user level threads is faster than context switching between kernel level threads

  • When a user thread is blocked all other threads of its processes are blocked

  • Kernel level threads cannot utilize multiprocessor systems by splitting threads on different processors or cores

Question 4

Assume that Source S and Destination D are connected through an intermediate router R. How many times a packet has to visit the network layer and data link layer during a transmission from S to D?

  • Network layer – 4 times, Data link layer – 4 times

  • Network layer – 4 times, Data link layer – 6 times

  • Network layer – 2 times, Data link layer – 4 times

  • Network layer – 3 times, Data link layer – 4 times

Question 5

Which of the following permutation can be obtained in the same order using a stack assuming that input is the sequence 5, 6, 7, 8, 9 in that order?

  • 7, 8, 9, 5, 6

  • 5, 9, 6, 7, 8

  • 7, 8, 9, 6, 5

  • 9, 8, 7, 5, 6

Question 6

The minimum number of stacks needed to implement a queue is

  • 3

  • 1

  • 2

  • 4

Question 7

Consider the program 

void function(int n) {
int i, j, count=0;
for (i=n/2; i <= n; i++)
for (j = 1; j <= n; j = j*2)
count++;}

The complexity of the program is

  • O(log n)

  • O(n2)

  • O(n2 log n)

  • O(n log n)

Question 8

Consider the recurrence equation

T(n) = 2T(n-1), if n>0
     = 1, otherwise

Then T(n) is (in big O order)

  • O(n)

  • O(2n)

  • O(1)

  • O(log n)

Question 9

A sorting technique is called stable if

  • If it takes O(n log n) time

  • It uses divide and conquer technique

  • Relative order of occurrence of non-distinct elements is maintained

  • It takes O(n) space

Question 10

Quick sort is run on 2 inputs shown below to sort in ascending order

A. 1, 2, 3……n
B. n, n – 1, n – 2 …… 1

Let C1 and C2 be the number of comparisons made for A and B respectively. Then

  • C1 > C2

  • C1 = C2

  • C1 < C2 
     

  • Cannot say anything for arbitrary n

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