ISC practical papers › ISC 2020 › Question 2

2D Array Rows as Octal Number

ISC 2020 Computer Science Practical, Question 2 · Arrays and matrices, Number programs

The question

Write a program to declare a Matrix A[][] of order (M x N) where 'M' is the number of rows and 'N' is the number of columns such that the value of 'M' must be greater than 0 and less than 10 and the value of 'N' must be greater than 2 and less than 6.

Allow the user to input digits (0-7) only at each location, such that each row represents an octal number.

Example: 2 3 1 (decimal equivalent of 1st row = 153 i.e. 2*8^2 + 3X8^1 + 1*8^0) 4 0 5 (decimal equivalent of 1st row = 261 i.e. 4*8^2 + 0X8^1 + 5*8^0) 1 5 6 (decimal equivalent of 1st row = 110 i.e. 1*8^2 + 5X8^1 + 6*8^0)

Perform the following tasks on the matrix: (a) Display the original matrix (b) Calculate the decimal equivalent for each row and display as per the format given below.

Example 1
INPUT
M = 1
N = 3
ENTER ELEMENTS FOR ROW 1: 1 4 4

OUTPUT
FILLED MATRIX        DECIMAL EQUIVALENT
1 4 4                100

Example 2
INPUT
M = 3
N = 4
ENTER ELEMENTS FOR ROW 1: 1 1 3 7
ENTER ELEMENTS FOR ROW 2: 2 1 0 6
ENTER ELEMENTS FOR ROW 3: 0 2 4 5

OUTPUT
FILLED MATRIX        DECIMAL EQUIVALENT
1 1 3 7                    607
2 1 0 6                    1094
0 2 4 5                    165

Example 3
INPUT
M = 3
N = 3
ENTER ELEMENTS FOR ROW 1: 2 4 8

OUTPUT
INVALID INPUT

Example 4
INPUT
M = 4
N = 6

OUTPUT
OUT OF RANGE

Question: ISC 2020 Computer Science Paper 2 (Practical), Question 2, set by the Council for the Indian School Certificate Examinations (CISCE). Solution and video: Vinay Singh.

Java solution

ISC2020Q2.java Download GitHub

import java.util.*;

class Matrix {
    private int M, N, A[][];

    public Matrix(int M, int N) {
        this.M = M;
        this.N = N;
        A = new int[M][N];
    }

    public void input() {
        Scanner in = new Scanner(System.in);
        for (int row = 0; row < M; row++) {
            System.out.print("ENTER ELEMENTS FOR ROW " + (row + 1) + ": ");
            for (int col = 0; col < N; col++) {
                A[row][col] = in.nextInt();
                if (!(A[row][col] >= 0 && A[row][col] <= 7)) {
                    System.out.println("OUTPUT\nINVALID INPUT");
                    System.exit(1);
                }
            }
        }
        in.close();
    }

    public void display() {
        int decimal;
        System.out.println("\nFILLED MATRIX\tDECIMAL EQUIVALENT");
        for (int row = 0; row < M; row++) {
            decimal = 0;
            for (int col = 0; col < N; col++) {
                System.out.print(A[row][col] + " ");
                decimal += A[row][col] * Math.pow(8, N - col - 1);
            }
            System.out.print("\b\t\t" + decimal + "\n");
        }
    }
}

public class ISC2020Q2 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int M, N;
        System.out.println("INPUT");
        System.out.print("M = ");
        M = in.nextInt();

        System.out.print("N = ");
        N = in.nextInt();

        if (M > 0 && M < 10 && N > 2 && N < 6) {
            Matrix A = new Matrix(M, N);
            A.input();
            System.out.println("OUTPUT");
            A.display();
        } else {
            System.out.println("OUTPUT\nOUT OF RANGE");
        }
        in.close();
    }
}

2D Array Rows as Octal Number

The question

Java solution

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