ISC Class 12 Computer Science previous year paper (2019)

Some of the members of the class are given below:

Class name	MatRev
Data members/instance variables:
arr[ ][ ]	to store integer elements
m	to store the number of rows
n	to store the number of columns
Member functions/methods:
MatRev(int mm, int nn)	parameterised constructor to initialise the data members m = mm and n = nn
void fillarray( )	to enter elements in the array
int reverse(int x)	returns the reverse of the number x
void revMat( MatRev P)	reverses each element of the array of the parameterized object and stores it in the array of the current object
void show( )	displays the array elements in matrix form

Define the class MatRev giving details of the constructor ( ), void fillarray (), int reverse(int), void revMat(MatRev) and void show(). Define the main () function to create objects and call the functions accordingly to enable the task.
Ans.

import java.io.*;
import java.util.*;
class MatRey{
   private int arr[][];
   private int m;
   private int n;
   public MatRev(int mm, int nn) {
      m=mm;
      n = nn;
      arr=newint[m][n];
   }
   public void fillArray( )throws IOException{
     Scanner sc = new Scanner(System.in);
     System.out.println("Enter matrix elements::");
     for(int i = 0; i < m; i++) {
        for(int j = 0; j < n; j++) {
           arr[i][j] = sc.nextInt();
        }
     }
  }
  public int reverse(int x) {
     int rev = 0;
     for(int i = x; i != 0; i /= 10)
       rev = rev * 10 + i % 10;
     return rev;
  }
  public void revMat(MatRev p) {
     for(int i = 0; i < m; i++) {
       for(int j = 0; j < n; j++) {
          this.arr[i] [j] = reverse(p.arr[i] [j]);
       }
     }
  }
  public void show() {
    for(int i = 0; i < m; i++) {
       for(int j = 0; j < n; j++) {
          System, out. print(arr[i][j] + "\t");
       }
       System.out.println();
    }
  }
  public static void main(String args[])throws IOException{
     Scanner sc = new Scanner(System.in);
     System.out.print("Enter number of rows::");
     int x = sc.nextInt();
     System.out.print("Enter number of columns::");
     int y = sc.nextInt();
     MatRev obj 1 = new MatRev(x, y);
     MatRev obj2 = new MatRev(x, y);
     obj1.fillArray();
     obj2.revMat(obj 1);
     System.out.println("Original Matrix is::");
     obj1.show();
     System.out.println("Matrix with reversed elements");
     obj2.show();
  }
}

Question 9.

A class Rearrange has been defined to modify a word by bringing all the vowels in the word at the beginning followed by the consonants.
Example:
      ORIGINAL becomes OIIARGNL
Some of the members of the class are given below:

Class name	Rearrange
Data member/instance variable:
wrd	to store a word
newwrd	to store the rearranged word
Member functions/methods:
Rearrange( )	default constructor
void readword( )	to accept the word in UPPER case
void freq_vow_con( )	finds the frequency of vowels and consonants in the word and displays them with an appropriate message
void arrange( )	rearranges the word by bringing the vowels at the beginning followed by consonants
void display( )	displays the original word along with the rearranged word

Specify the class Rearrange, giving the details of the constructor(), void readword(), void freq _vow_con(), void arrange() and void display(). Define the main() function to create an object and call the functions accordingly to enable the task.
Ans.

import java.io.*;
import java.util.*;
class Rearrange {
   private String wrd;
      private String newwrd;
      public Rearrange() {
         wrd = new String();
         newwrd = new String();
      }
      public void readword() throws IOException {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the word:");
        wxd = sc.next();
     }
     public void freq_vow_con() {
       wrd = wrd.toUpperCase();
       int v = 0;
       int c = 0;
       forint i = 0; i < wrd.length(); i++) {
         char ch = wrd. char At(i);
         if(Character.isLetter(ch)) {
            switch(ch) {
               case 'A':
               case'E':
               case T:
               case 'O':
               case 'U':
               v++;
               break;
               default:
               C++;
           }
         }
      }
      System.out.println("Frequency of vowels: "+v);
      System.out.println("Frequency of consonants: "+c);
    }
    public void arrange() {
       String v = new String();
       String c = new String();
       wrd = wrd.toUpperCase();
       for(int i = 0; i < wrd. length(); i++) {
          char ch = wrd.charAt(i);
          if(Character.isLetter!ch)) {
             switch(ch) {
                case 'A':
                case'E':
                case T:
                case 'O':
                case 'U':
                v += ch;
                 break;
                default:
                c + = ch;
            }
          }
       }
       newwrd = v + c;
   }
   public void display() {
      System.out.println("Original word:" + wrd);
      System.out.prfntln("Rearranged word:" + newwrd);
   }
   public static void main(String args[])throws IOException {
      Rearrange obj = new Rearrange();
      obj.readword();
      obj.freq_vow_con();
      obj.arrange();
      obj.display();
   }
}

Section – C
Answer any two questions.

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 superclass Record contains names and marks of the students in two different single dimensional arrays. Define a subclass Highest to display the names of the students obtaining the highest mark 
The details of the members of both classes are given below:

Class name	Record
Data member/instance variable:
n[ ]	array to store names
m[ ]	array to store marks
size	to store the number of students
Member functions/methods:
Record(int cap)	parameterized constructor to initialize the data member size = cap
void readarray()	to enter elements in both the arrays
void display( )	displays the array elements
Class name:	Highest
Data member/instance variable:
ind	to store the index
Member functions/methods:
Highest(…)	parameterized constructor to initialize the data members of both the classes
void find( )	finds the index of the student obtaining the highest mark and assign it to ‘ind’
void display( )	display( ) : displays the array elements along with the names and marks of the students who have obtained the highest mark

Assume that the superclass Record has been defined. Using the concept of inheritance, specify the class Highest giving the details of the constructor(…), void find() and void display().
The superclass, main function and algorithm need NOT be written.
Ans.

class Record
{
   protected String n[];
   protected int m[];
   protected int size;
   public Recordfint cap) {
   }
   public void readarray() {
   }
   public void display() {
   }
}
class Highest extends Record {
   private int ind;
   public Highest(int cap) {
      super(cap)
   }
   public void find() {
      ind = 0;
      for (int i = 0; i < size; i++) { 
         if(m[i]>m[ind]){
            ind = i;
          }
      }
   }
   public void display() {
      super.display();
      System.out.println("Highest marks are::" +m[ind]);
      System.out.println("Students who score the highest marks are::");
      for (int i = 0; i < size; i++) }
         if(m[i] == m[ind]) {
             System.out.println(n[i]);
         }
      }
   }
}

Question 11.

A linear data structure enables the user to add an address from rear end and remove address from front. Define a class Diary with the following details :

Class name	Diary
Data members / instance variables:
Q[ ]	array to store the addresses
size	stores the maximum capacity of the array
start	to point the index of the front end
end	to point the index of the rear end
Member functions:
Diary (int max)	constructor to initialize the data member size=max, start=0 and end=0
void pushadd(String n)	to add address in the diary from the rear end if possible, otherwise display the message “ NO SPACE”
String popadd( )	removes and returns the address from the front end of the diary if any, else returns “?????”
void show( )	void show( ) : displays all the addresses in the diary

(a) Specify the class Diary giving details of the functions void pushadd(String) and String popadd(). Assume that the other functions have been defined. 
The main function and algorithm need NOT be written.
Ans.

class Diary {
    public void pushAdd(String n) {
       if(Q[0].equals(""))
          Q[0] = n;
       else if(end + 1 < size) Q[end + 1] = n; 
       else System.out.println("NO SPACE"); 
    } public String popadd() { if(start -1 >= 0)
     return Q[start--];
    else
         return "?????";
  }
}

(b) Name the entity used in the above data structure arrangement. 
Ans. (b) Queue

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 find and display the sum of even integers from an existing linked list.
The method declaration is as follows:
void SumEvenNode(Node str)
Ans.

void sumEvenNode(Node str) { 
   if(str = null) 
      return 0; 
   else if(str.num % 2 == 0) 
      return str.num + sumEvenNode(str.next); 
   else return 0 + sumEvenNode(str.next);

(b) Answer the following questions from the diagram of a Binary Tree given below: