ISC Class 12 Computer Science previous year paper (2017)

(b) Prove: F = (x’+z) + [ (y’+z).(x’+y) ] ‘ =1
                     = (x’+z) + (y’+z)’ + (x’+y)’ ( De Morgan Law)
                     = x’+z + y.z’ + xy’ (Distributive Law)
                     = (x’+x)(x’+y’) + (z+z’)(z+y)
                     = x’+y’+z+y
                     = 1 (as y+y’=1) (Identity Law)

(c) Maxterm : It is the sum of all its literals.
      Minterms : It is the product of all its literals.
          When P= 0 , Q = 1 , R = 1 , S = 0
     Maxterm = P + Q’ + R’ + S
     Minterms = P’ Q R S’

SECTION – B
Answer any two questions.

Question 7 [marks 10]

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:

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

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.

import java.util.*;
public class Palin
{
   int num,revnum;
   static Scanner x=new Scanner(System.in);
   Palin()
   { 
      num=0;revnum=0;
   }
   void accept()
   { 
      System.out.println( "Enter a number");
      num=x.nextInt();
   }
   int reverse(int y)
   {
      if(y>0)
      { 
         revnum =revnum * 10 + y%10;
         return reverse(y/10);
      }
      else
         return revnum;
   }
   void check()
   {
      int p=num;
      if( num==reverse(p))
        System.out.println("palindrome");
      else
        System.out.println("not a palindrome");
   }
   static void main()
   {
      Palin obj=new Palin();
      obj.accept();
      obj.check();
   }
}

Question 8 [marks 10]

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:

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.

import java.util.*;
public class Adder
{
   int a[]=new int[2];
   static Scanner x=new Scanner(System.in);
   Adder()
   { a[0]=0;a[1]=0;
   }
   void readtime()
   { 
      System.out.println("Enter hours and minutes");
      a[0]=x.nextInt();
      a[1]=x.nextInt();
   }
   void disptime()
   {
      System.out.println("Hours=" + a[0]);
      System.out.println("Minutes=" + a[1]);
   }
   void addtime(Adder X,Adder Y)
   { 
      a[1]=X.a[1] + Y.a[1];
      a[0]=a[1]/60;
      a[1]=a[1]%60;
      a[0] += X.a[0] + Y.a[0];
  }
  static void main()
  { 
     Adder a=new Adder();
     Adder b=new Adder();
     Adder c=new Adder();
     a.readtime();
     b.readtime();
     c.addtime(a,b);
     c.disptime();
  }
}

Question 9 [marks 10]

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:

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
Member functions/methods:
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.

import java.util.*;
public class SwapSort
{ 
   String wrd,swapwrd,sortwrd;
   int len;
   static Scanner x=new Scanner(System.in);
   SwapSort()
   {
     swapwrd="";
     sortwrd="";
   }
   void readword()
   {
     System.out.println("Enter word in Upper case");
     wrd=x.next();
     len=wrd.length();
   }
   void swapchar()
   { 
       swapwrd=wrd.charAt(len-1) + wrd.substring(1,len-1) + wrd.charAt(0);
   }
   void sortword()
   { 
      char c;
      for(int i=65;i<=90;i++)
      { 
         for(int j=0;j<len;j++)
         { 
           c=wrd.charAt(j);
           if(c==i)
             sortwrd += c;
         }
      }
  }
  void display()
  {
     System.out.println("Original word = " + wrd);
     System.out.println("Swapped word = " + swapwrd);
     System.out.println("Sorted word = " + sortwrd);
  }
  static void main()
  { 
     SwapSort x=new SwapSort();
     x.readword();
     x.swapchar();
     x.sortword();
     x.display();
  }
}

SECTION – C
Answer any two questions.

Question 10 [marks 5]

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.
Some of the members of both the classes are given below:

Class name	Product
Data members / instance variables:
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)
Member functions :
product (String n, int c, double p)	: parameterized constructor to assign values to data embers name=n, code=c and amount = p displays the details of the data members.
void show()	: displays the details of the data members
Class name	Sales
Data members / instance variables:
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)
Member functions :
Sales(…)	: parameterized constructor to assign values to data
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.

public class Sales extends Product
{ 
   int day;
   double tax,totamt;
   Sales( String n,int a, double b, int d)
   { 
      super(n,a,b);
      day=d;
   }
   void compute()
   { 
     double f=0.0;
     tax= (12.4 /100) * amount;
     if(day>27)
       f=(2.5/100)* amount;
     totamt= amount+tax+f;
   }
   void show()
   { 
     super.show();
     System.out.println("No of days=" + day);
     System.out.println("Sales Tax=" + tax);
     System.out.println("Total Amount=" + totamt );
   }
}

Question 11 [marks 5]

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:

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.

public class Queue
{ 
   int Que[]=new int[100];
   int max,f,r;
   void addele(int v)
   { 
      if(r<max-1)
        Que[++r]=v;
      else
        System.out.println("Overflow");
   }
   int delele()
   { 
     if(f!=r)
       return Que[++f];
     else
       return -9999;
   }
}

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: [2]
         int CountOdd( Node startPtr )
(b) Answer the following questions from the diagram of a Binary Tree given below: