ISC Class 12 Computer Science previous year paper (2020)

(c) Simplify :[(X’+Y)•(Y’+Z)]’ + (X’+Z)
                  = (X’+Y)’ + (Y’+Z)’ + (X’+Z)
                 = XY’ + YZ’ + X’ + Z
                 = X’ + XY’ + Z + YZ’
                 = (X’+X)•(X’+Y’)+(Y+Z)•(Z+Z’)
                 = X’+Y’+Z +Y
                 = 1 as ( Y + Y’ =1)

SECTION – B
Answer any two questions.

Question 7 [ 10 marks]

Design a class Convert to find the date and the month from a given day number for a particular year.
Example: If day number is 64 and the year is 2020, then the corresponding date would be:
        March 4, 2020 i.e. (31 + 29 + 4 = 64)
        Some of the members of the class are given below:

Classname	Convert
Data members/instance variables:
n	integer to store the day number
d	integer to store the day of the month (date)
m	integer to store the month
y	integer to store the year
Methods/Member functions:
Convert ( )	constructor to initialize the data members with legal initial values
void accept( )	to accept the day number and the year
void day_to_date( )	converts the day number to its corresponding date for a particular year and stores the date in ‘d’ and the month in ‘m’
void display( )	displays the month name, date and year

Specify the class Convert giving details of the constructor( ),void accept( ), void day_to_date( ) and voiddisplay( ).
Define a main( ) function to create an object and call the functions accordingly to enable the task.

import java.util.*;
class Convert
{ 
   int n,d,m,y;
   Convert( )
   {
      n=0;
      y=0;
   }
   void accept()
   { 
      Scanner x=new Scanner(System.in) ;
      System.out.println(("Enter day number and year") ;
      n=x.nextInt() ;
      y=x.nextInt() ;
   } 
   void day_to_date()
   { 
      int a[]={0,31,28,31,30,31,30,31,31,30,31,30,31};
      if(y%4==0)
      a[2]=29;
      int s=0, c=0;
      while(s<n) 
        s=s+a[c++]; 
      s=s-a[--c];
      d=n-s;
      m=c;
   }
   void display()
   { 
      String x[]={"","JANUARY","FEBRUARY","MARCH","APRIL","MAY", "JUNE","JULY","AUGUST","SEPTEMBER","OCTOBER","NOVEMBER","DECEMBER"};
      System.out.print("\n Day Number: " + n);
      System.out.print("\n Date: " ); 
      System.out.print(x[m]+" " +d + "," + y);
   }
   static void main()
   { 
      Convert obj =new Convert();
      obj.accept( ) ; 
      obj.day_to_date();
      obj.display();
   }
}

Question 8 [ 10 marks]

Design a class BinSearch to search for a particular value in an array.
Some of the members of the class are given below:

Classname	BinSearch
Data members/instance variables:
arr[ ]	to store integer elements
n	integer to store the size of the array
Member functions/methods:
BinSearch(int nn )
void fillarray( )
void sort( )
void sort( )	searches for the value ‘v’ using binary search and recursive technique and returns its location if found otherwise returns -1

Define the class BinSearch giving details of the constructor( ), void fillarray( ), void sort( ) and int bin_search(int,int,int).
Define the main( ) function to create an object and call the functions accordingly to enable the task.

import java.util.*;
class BinSearch
{ 
  int arr[];
  int n; 
  static Scanner x=new Scanner(System.in);
  BinSearch(int nn)
  { 
    n=nn; 
  }  
  void fillarray()
  { 
     arr=new int[n];
     System.out.println("Enter "+n + " elements");
     for(int i =0;i<n;i++)
     arr[i]=x.nextInt();
  }
  void sort()
  { 
     int t;
     for(int i=0;i<n-1;i++)
     for(int j =0;j<n-1-i;j++)
     { 
        if (arr[j]>arr[j+1])
        { 
           t=arr[j];
           arr[j]=arr[j+1];
           arr[j+1]=t;
        }
     }
  }
  int bin_search(int l,int u, int v )
  { 
     int m=(l+u)/2;
     if(arr[m]==v)
       return m;
     else if(l>u) 
       return -1;
     else if (arr[m]>v)
       return bin_search(l,m-1,v);
     else
       return bin_search(m+1,u,v);
  }
  static void main()
  {
     BinSearch obj = new BinSearch(5);
     obj.fillarray();
     obj.sort();
     System.out.println(" location: " + obj.bin_search(0,4,20) );
  }
}

Question 9 [ 10 marks]

A class Mix has been defined to mix two words, character by character, in the following manner:
The first character of the first word is followed by the first character of the second word and so on. If the words are of different length, the remaining characters of the longer word are put at the end.
Example: If the First word is “JUMP” and the second word is “STROLL”, then the required word will be “JSUTMRPOLL”
Some of the members of the class are given below:

Classname	Mix
Data member/instance variable:
wrd	to store a word
len	to store the length of the word
Member functions/methods:
Mix( )	default constructor to initialize the data members with legal initial values
void feedword( )	to accept the word in UPPER case
void mix_word( Mix P, Mix Q )	mixes the words of objects P and Q as stated above and stores the resultant word in the current object
void display( )	displays the word

Specify the class Mix giving the details of the constructor( ), void feedword( ), void mix_word( Mix, Mix ) and void display( ). Define the main( ) function to create objects and call the functions accordingly to enable the task.

import java.util.*;
class Mix
{ 
   String wrd;
   int len;
   static Scanner x=new Scanner(System.in);
   Mix()
   {
      wrd="";
      len=0;
   }
   void feedword()
   { 
      System.out.println( "Enter a word in UPPER CASE");
      wrd=x.next();
      len=wrd.length();
   }
   void mix_word(Mix P,Mix Q)
   { 
      int s=(P.len <Q.len)? P.len:Q.len;
      for(int i=0;i<s;i++)
        wrd += P.wrd.charAt(i)+""+Q.wrd.charAt(i);
      if (P.len > Q.len)
         wrd +=P.wrd.substring(Q.len);
      else
         wrd +=Q.wrd.substring(P.len);
   }
   void display()
   {
      System.out.println("WORD = " + wrd);
   }
   static void main()
   { 
      Mix obj=new Mix();
      Mix obj1=new Mix();
      Mix obj2= new Mix(); 
      obj.feedword();
      obj1.feedword();
      obj2.mix_word (obj,obj1);
      obj2.display();
   }
}

SECTION – C
Answer any two questions.

Question 10 [marks in brackets ]

A Circular queue is a linear data structure which works on the principle of FIFO, enables the user to enter data from the rear end and remove data from the front end with the rear end connected to the front end to form a circular pattern. Define a class CirQueue with the following details:

Class name	CirQueue
Data member/instance variable:
cq[ ]	array to store the integers
cap	stores the maximum capacity of the array
front	to point the index of the front end
rear	to point the index of the rear end
Member functions/methods:
CirQueue (int max)	constructor to initialize the data member cap=max, front=0 and rear=0
void push(int n)	to add integer in the queue from the rear end if possible, otherwise display the message “QUEUE IS FULL”
int pop( )	removes and returns the integer from the front end of the queue if any, else returns – 9999
void show( )	displays the queue elements

(a) Specify the class CirQueue giving details of the functions void push(int) and int pop( ). Assume that the other functions have been defined. The main function and algorithm need NOT be written. [4]
(b) How is a linear queue structure different from a circular queue structure? [1]

(a)

class CirQueue
{
   void push(int v)
   { 
      if( (rear+1)% cap !=front)
      { 
         rear = (rear + 1)% cap ;
         cq[rear] =v;
      }
      else
         System.out.println(" QUEUE IS FULL");
   }
   int pop()
   { 
      if (front != rear)
      { 
         front = ( front + 1)% cap ;
         return cq[front];
      }
      else
         return -9999;
   } 
}

(b) In linear queue structure the front index is always less or equal to rear index, whereas in Circular queue the front index may be greater than rear index.

Question 11 [5 marks]

An interface Data is defined with a data member and a method volume( ) which returns the volume of the implementing shape. A super class Base has been defined to contain the radius of a geometrical shape. Define a sub class CalVol which uses the properties of the interface Data and the class Base and calculates the volume of a cylinder.
The details of the members of the interface and both the classes are given below:

Interface name	Data
Data member:
double pi	initialize pi = 3.142
Member functions/methods:
double volume( )
Class name:	Base
Data member/instance variable:
rad	to store the radius in decimal
Member functions/methods:
Base(…)	parameterized constructor to initialize the data member
void show( )	displays the radius with an appropriate message
Class name:	CalVol
Data member/instance variable:
ht	to store the height in decimal
Member functions/methods:
CalVol(…)	parameterized constructor to initialize the data members of both the classes
double volume( )	calculates the volume of a sphere by using the formula ( pi x radius^2 x height )
void show( )	displays the data members of both the classes and the volume of the sphere with appropriate message

Assume that the interface Data and the super class Base has been defined. Using the concept of inheritance, specify the class CalVol giving the details of the constructor(…), double volume( ) and void show( ).
The interface, super class, main function, and algorithm need NOT be written.

class CalVol extends Base implements Data
{ 
   double ht;
   CalVol(double r, double h)
   { 
      super(r);
      ht=h;
   }
   public double volume()
   { 
      double x=pi * rad *rad * ht;
      return x;
   }
   void show()
   { 
      super.show();
      System.out.println("Height= " + ht);
      System.out.println("Volume= " + volume());
   }
}

Question 12 [marks in brackets ]

(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 n;
   Node next;
}

Write an Algorithm OR a Method to find the product of the integer numbers from an existing linked list. 
   The method declaration is as follows:
         void Product_Node( Node str ) [2]
(b) Answer the following questions from the diagram of a Binary Tree given below: