Computer Science Paper 1 (Theory) - 2017.pdf

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This Paper consists of 9 printed pages and 1 blank page.
1217-868 A Turn over
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COMPUTER SCIENCE
PAPER 1
(THEORY)
(Maximum Marks: 70)
(Time allowed: Three hours)
(Candidates are allowed additional 15 minutes for only reading the paper.
They must NOT start writing during this time.)
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Answer all questions in Part I (compulsory) and six questions from Part-II, choosing two
questions from Section-A, two from Section-B and two from Section-C .
All working, including rough work, should be done on the same sheet as the
rest of the answer.
The intended marks for questions or parts of questions are given in brackets [ ].
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PART I (20 Marks)
Answer all questions.
While answering questions in this Part, indicate briefly your working and reasoning,
wherever required.
Question 1
(a) State the law represented by the following proposition and prove it with the help
of a truth table:
P V P = P
[1]
(b) State the Principle of Duality. [1]
(c) Find the complement of the following Boolean expression using De Morgan’s law:
F(a,b,c) = (bʹ + c) + a
[1]
(d) Draw the logic diagram and truth table for a 2 input XNOR gate. [1]
(e) If (~P => Q) then write its: [1]
(i) Inverse
(ii) Converse

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Question 2
(a) What is an interface? How is it different from a class? [2]
(b) Convert the following infix expression to postfix form:
P * Q / R + (S + T)
[2]
(c) A matrix P[15][10] is stored with each element requiring 8 bytes of storage. If the
base address at P[0][0] is 1400, determine the address at P[10][7] when the matrix
is stored in Row Major Wise.
[2]
(d) (i) What is the worst case complexity of the following code segment:
for (int x = 1; x <=a; x++)
{
statements;
}
for (int y = 1; y <=b; y++)
{
for (int z = 1; z <=c; z++)
{
statements;
}
}
[2]
(ii) How would the complexity change if all the three loops went to N instead of
a, b and c?
(e) Differentiate between a constructor and a method of a class. [2]
Question 3
The following function magicfun( ) is a part of some class. What will the function
magicfun( ) return, when the value of n=7 and n=10, respectively? Show the dry
run/working:
int magicfun( int n)
{ if ( n= = 0)
return 0;
else
return magicfun(n/2) * 10 + (n % 2);
}
[5]

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PART – II (50 Marks)
Answer six questions in this part, choosing two questions from
Section A, two from Section B and two from Section C.
SECTION - A
Answer any two questions.
Question 4
(a) Given the Boolean function F(A, B, C, D) = Ʃ (2,3,4,5,6,7,8,10,11).
(i) Reduce the above expression by using 4-variable Karnaugh map, showing
the various groups (i.e. octal, quads and pairs).
[4]
(ii) Draw the logic gate diagram for the reduced expression. Assume that the
variables and their complements are available as inputs.
[1]
(b) Given the Boolean function F(P, Q, R, S) = 𝝅(0,1,2,4,5,6,8,10).
(i) Reduce the above expression by using 4-variable Karnaugh map, showing
the various groups (i.e. octal, quads and pairs).
[4]
(ii) Draw the logic gate diagram for the reduced expression. Assume that the
variables and their complements are available as inputs.
[1]
Question 5
(a) A school intends to select candidates for an Inter-School Essay Competition as
per the criteria given below:
 The student has participated in an earlier competition and is very
creative.
OR
 The student is very creative and has excellent general awareness, but
has not participated in any competition earlier.
OR
 The student has excellent general awareness and has won prize in an
inter-house competition.
The inputs are:
INPUTS
A participated in a competition earlier
B is very creative
C won prize in an inter-house competition
D has excellent general awareness
(In all the above cases 1 indicates yes and 0 indicates no).
Output : X [1 indicates yes, 0 indicates no for all cases]
Draw the truth table for the inputs and outputs given above and write the POS
expression for X(A,B,C,D).
[5]

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(b) State the application of a Half Adder. Draw the truth table and circuit diagram for a
Half Adder.
[3]
(c) Convert the following Boolean expression into its canonical POS form:
F(A,B,C) = ( B + Cʹ) · (Aʹ + B)
[2]
Question 6
(a) What is a Multiplexer? How is it different from a decoder? Draw the circuit
diagram for a 8:1 Multiplexer.
[5]
(b) Prove the Boolean expression using Boolean laws. Also, mention the law used at
each step.
F = (xʹ + z) + [ (yʹ + z) • (xʹ + y) ]ʹ = 1
[3]
(c) Define maxterms and minterms. Find the maxterm and minterm when:
P = 0, Q = 1, R = 1 and S = 0
[2]
SECTION – B
Each program should be written in such a way that it clearly depicts the logic of the problem.
This can be achieved by using mnemonic names and comments in the program.
(Flowcharts and Algorithms are not required.)
The programs must be written in Java.
Question 7
A class Palin has been defined to check whether a positive number is a Palindrome
number or not.
The number ‘N’ is palindrome if the original number and its reverse are same.
Some of the members of the class are given below:
[10]
Class name : Palin
Data members/instance variables:
num : integer to store the number
revnum : integer to store the reverse of the number
Methods/Member functions:
Palin( ) : constructor to initialize data members with
legal initial values
void accept( ) : to accept the number
int reverse(int y) : reverses the parameterized argument ‘y’ and
stores it in ‘revnum’ using recursive
technique
void check( ) : checks whether the number is a Palindrome by
invoking the function reverse( ) and display
the result with an appropriate message

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Specify the class Palin giving the details of the constructor( ), void accept( ),
int reverse( int ) and void check( ). Define the main( ) function to create an object and
call the functions accordingly to enable the task.
Question 8
A class Adder has been defined to add any two accepted time.
Example: Time A - 6 hours 35 minutes
Time B - 7 hours 45 minutes
Their sum is - 14 hours 20 minutes ( where 60 minutes = 1 hour)
The details of the members of the class are given below:
[10]
Class name : Adder
Data member/instance variable:
a[ ] : integer array to hold two elements (hours and
minutes)
Member functions/methods:
Adder( ) : constructor to assign 0 to the array elements
void readtime( ) : to enter the elements of the array
void addtime( Adder X, Adder Y) : adds the time of the two parameterized objects
X and Y and stores the sum in the current
calling object
void disptime( ) : displays the array elements with an appropriate
message (i.e. hours = and minutes = )
Specify the class Adder giving details of the constructor( ), void readtime( ),
void addtime(Adder, Adder) and void disptime( ). Define the main( ) function to create
objects and call the functions accordingly to enable the task.

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Question 9
A class SwapSort has been defined to perform string related operations on a word input.
Some of the members of the class are as follows:
[10]
Class name : SwapSort
Data members/instance variables:
wrd : to store a word
len : integer to store length of the word
swapwrd : to store the swapped word
sortwrd : to store the sorted word
SwapSort( ) : default constructor to initialize data members
with legal initial values
void readword( ) : to accept a word in UPPER CASE
void swapchar( ) : to interchange/swap the first and last characters
of the word in ‘wrd’ and stores the new word
in ‘swapwrd’
void sortword( ) : sorts the characters of the original word in
alphabetical order and stores it in ‘sortwrd’
void display( ) : displays the original word, swapped word and
the sorted word
Specify the class SwapSort, giving the details of the constructor( ), void readword( ),
void swapchar( ), void sortword( ) and void display( ). Define the main( ) function to
create an object and call the functions accordingly to enable the task.
SECTION – C
Each program should be written in such a way that it clearly depicts the logic of the problem
stepwise.
This can be achieved by using comments in the program and mnemonic names or pseudo codes for
algorithms. The programs must be written in Java and the algorithms must be written in general /
standard form, wherever required / specified.
(Flowcharts are not required.)
Question 10
A super class Product has been defined to store the details of a product sold by a
wholesaler to a retailer. Define a sub class Sales to compute the total amount paid by the
retailer with or without fine along with service tax.
[5]

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Some of the members of both the classes are given below:
Class name : Product
name : stores the name of the product
code : integer to store the product code
amount : stores the total sale amount of the product (in
decimals)
Product(String n, int c, double p) : parameterized constructor to assign data
members name=n, code=c and amount = p
void show( ) : displays the details of the data members
Class name: Sales
day : stores number of days taken to pay the sale
amount
tax : to store the service tax (in decimals)
totamt : to store the total amount (in decimals)
Sales(…) : parameterized constructor to assign values to
data members of both the classes
void compute( ) : calculates the service tax @ 12·4% of the actual
sale amount
calculates the fine @ 2·5% of the actual sale
amount only if the amount paid by the retailer to
the wholesaler exceeds 30 days
calculates the total amount paid by the retailer as
(actual sale amount + service tax + fine)
void show( ) : displays the data members of super class and the
total amount
Assume that the super class Product has been defined. Using the concept of inheritance,
specify the class Sales giving the details of the constructor(…),void compute( ) and
void show( ).
The super class, main function and algorithm need NOT be written.

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Question 11
Queue is an entity which can hold a maximum of 100 integers. The queue enables the
user to add integers from the rear and remove integers from the front.
Define a class Queue with the following details:
[5]
Class name : Queue
Data Members / instance
variables:
Que[ ] : array to hold the integer elements
size : stores the size of the array
front : to point the index of the front
rear : to point the index of the rear
Member functions:
Queue (int mm) constructor to initialize the data
size = mm, front = 0, rear = 0
void addele(int v ) : to add integer from the rear if possible
else display the message “Overflow”
int delele( ) : returns elements from front if present,
otherwise displays the message
“Underflow” and return -9999
void display ( ) : displays the array elements
Specify the class Queue giving details of ONLY the functions void addele(int) and
int delele( ). Assume that the other functions have been defined.
The main function and algorithm need NOT be written.
Question 12
(a) A linked list is formed from the objects of the class Node. The class structure of the
Node is given below:
class Node
{
int num;
Node next;
}
Write an Algorithm OR a Method to count the nodes that contain only odd integers
from an existing linked list and returns the count.
The method declaration is as follows:
int CountOdd( Node startPtr )
[2]

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(b) Answer the following questions from the diagram of a Binary Tree given below:
(i) Write the postorder traversal of the above tree structure. [1]
(ii) State the level numbers of the nodes N and R if the root is at 0 (zero) level. [1]
(iii) List the internal nodes of the right sub-tree. [1]
M
N G
W Y Z D
R
F

Computer Science Paper 1 (Theory) - 2017.pdf

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