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Solved 2015 Practical Paper ISC Computer Science

Class 12 - ISC Computer Science Solved Practical Papers

Rotate Matrix 90 Degrees Program - ISC 2015 Practical

Write a program to declare a square matrix a[][] of order M × M where ‘M’ is the number of rows and the number of columns, such that M must be greater than 2 and less than 10. Accept the value of M as user input. Display an appropriate message for an invalid input. Allow the user to input integers into this matrix. Perform the following tasks:

(a) Display the original matrix.
(b) Rotate the matrix 90o clockwise as shown below:

Original matrix        Rotated matrix
1 2 3                  7 4 1
4 5 6                  8 5 2
7 8 9                  9 6 3

(c) Find the sum of the elements of the four corners of the matrix.

Test your program for the following data and some random data:

Example 1:
INPUT:
M = 3

3    4    9
2    5    8
1    6    7

OUTPUT:
ORIGINAL MATRIX

3    4    9
2    5    8
1    6    7

MATRIX AFTER ROTATION

1    2    3
6    5    4
7    8    9

Sum of the corner elements = 20

Example 2:
INPUT:
M = 4

1    2    4    9
2    5    8    3
1    6    7    4
3    7    6    5

OUTPUT:

ORIGINAL MATRIX

1    2    4    9
2    5    8    3
1    6    7    4
3    7    6    5

MATRIX AFTER ROTATION

3    1    2    1
7    6    5    2
6    7    8    4
5    4    3    9

Sum of the corner elements = 18

Example 3:
INPUT:
M = 14
OUTPUT:
SIZE OUT OF RANGE

Java 

import java.io.*;
    class Rotate{
    public static void main(String args[])throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("M = ");
        int m = Integer.parseInt(br.readLine());
        if(m < 3 || m > 9){
            System.out.println("SIZE OUT OF RANGE");
            return;
        }

        int a[][] = new int[m][m];
        System.out.println("Enter matrix elements:");
        for(int i = 0; i < m; i++){
            for(int j = 0; j < m; j++){
                a[i][j] = Integer.parseInt(br.readLine());
            }
        }
        System.out.println("ORIGINAL MATRIX");
        for(int i = 0; i < m; i++){
            for(int j = 0; j < m; j++){
                System.out.print(a[i][j] + "\t");
            }
            System.out.println();
        }

        int r[][] = new int[m][m];
        int row = 0; int col = m - 1;
        for(int i = 0; i < m; i++){
            row = 0;
            for(int j = 0; j < m; j++){
                r[row++][col] = a[i][j];
            }
            col--;
        }

        System.out.println("MATRIX AFTER ROTATION");
        for(int i = 0; i < m; i++){
            for(int j = 0; j < m; j++){
                System.out.print(r[i][j] + "\t");
            }
            System.out.println();
        }
        int last = m - 1;
        int sum = a[0][0] + a[0][last] + a[last][0] + a[last][last];
        System.out.println("Sum of the corner elements = " + sum);
    }
}

Output

 
OUTPUT 1:
M = 3
Enter matrix elements:
1
2
3
4
5
6
7
8
9
ORIGINAL MATRIX
1   2   3   
4   5   6   
7   8   9   
MATRIX AFTER ROTATION
7   4   1   
8   5   2   
9   6   3   
Sum of the corner elements = 20

OUTPUT 2:
M = 4
Enter matrix elements:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
ORIGINAL MATRIX
1   2   3   4   
5   6   7   8   
9   10  11  12  
13  14  15  16  
MATRIX AFTER ROTATION
13  9   5   1   
14  10  6   2   
15  11  7   3   
16  12  8   4   
Sum of the corner elements = 34
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