Question

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

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

Share code with your friends

Code

import java.util.Scanner;
public class RotateMatrix
{
    public static void main(String args[])
    {
        int i=0,j=0,m=0,row=0,col=0,sum=0;
        int arr[][],r[][];
        Scanner sc=new Scanner(System.in);
        System.out.print("M = ");
        m = sc.nextInt();
        if(m < 3 || m > 9)
        {
            System.out.println("SIZE OUT OF RANGE");

        }
        else
        {
            arr = new int[m][m];
            System.out.println("Enter matrix elements:");
            for(i = 0; i < m; i++)
            {
                for(j = 0; j < m; j++)
                {
                    arr[i][j] = sc.nextInt();
                }
            }
            System.out.println("ORIGINAL MATRIX");

            for(i = 0; i < m; i++)
            {
                for(j = 0; j < m; j++)
                {
                    System.out.print(arr[i][j] + "\t");
                }
                System.out.println();
            }
            r = new int[m][m];
            row = 0;
            col = m - 1;

            for(i = 0; i < m; i++)
            {
                row = 0;
                for(j = 0; j < m; j++)
                {
                    r[row][col] = arr[i][j];
                    row++;
                }
                col--;
            }

            System.out.println("MATRIX AFTER ROTATION");
            for(i = 0; i < m; i++)
            {
                for(j = 0; j < m; j++)
                {
                    System.out.print(r[i][j] + "\t");
                }
                System.out.println();
            }

            sum = arr[0][0] + arr[0][(m-1)] + arr[(m-1)][0] + arr[(m-1)][(m-1)];
            System.out.println("Sum of the corner elements = " + sum);
        }
    }
}