public class Hollowrect {
    public static void HollowrectPattern(int noOfRows, int noOfCols) {
        // for rows outer loop
        for (int i = 1; i <= noOfRows; i++) {
            // inner loop
            for (int j = 1; j <= noOfCols; j++) {
                // cell (i,j)
                if (i == 1 || i == noOfRows || j == 1 || j == noOfCols) {
                    System.out.print("*");

                } else {
                    System.out.print(" ");
                }

            }
            System.out.println();

        }

    }

    public static void main(String[] args) {
        HollowrectPattern(4, 7);

    }
}

*******
*     *
*     *
*******

public class Butterflypattern {
    public static void butterfly_pattern(int n) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print("*");

            }
            for (int j = 1; j <= 2 * (n - i); j++) {
                System.out.print(" ");

            }
            for (int index = 1; index <= i; index++) {
                System.out.print("*");

            }
            System.out.println();

        }
        for (int i = n; i >= 1; i--) {
            for (int j = 1; j <= i; j++) {
                System.out.print("*");

            }
            for (int j = 1; j <= 2 * (n - i); j++) {
                System.out.print(" ");

            }
            for (int index = 1; index <= i; index++) {
                System.out.print("*");

            }
            System.out.println();

        }

    }

    public static void main(String[] args) {
        butterfly_pattern(5);

    }
}

*        *
**      **
***    ***
****  ****
**********
**********
****  ****
***    ***
**      **
*        *

public class diamond {
    public static void diamond_pattern(int n) {
        for (int i = 1; i <= n; i++) {
            // blank space
            for (int j = 1; j <= (n - i); j++) {
                System.out.print(" ");

            }
            // star
            for (int j = 1; j <= 2 * (i - 1) + 1; j++) {
                System.out.print("*");

            }
            System.out.println();

        }
        for (int i = n; i >= 1; i--) {
            // blank space
            for (int j = 1; j <= (n - i); j++) {
                System.out.print(" ");

            }
            // star
            for (int j = 1; j <= 2 * (i - 1) + 1; j++) {
                System.out.print("*");

            }
            System.out.println();

        }

    }

    public static void main(String[] args) {
        diamond_pattern(5);

    }
}

    *
   ***
  *****
 *******
*********
*********
 *******
  *****
   ***
    *

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