Kyle Kyle - 21 days ago 15
Java Question

Print a Z shape pyramid using * stars

I am trying to write a program that outputs a Z pattern that is

n
number of
*
across the top, bottom, and connecting line using for loops.

Example:

Enter a number: 6

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


This is my current code, it's producing a half pyramid upside down.

import java.util.*;

public class ZShape {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);

System.out.print("Enter a number: ");
int n = input.nextInt();

for (int x = 0; x <= n; x++) {
for (int y = n; y >= 1; y--) {
if (y > x) {
System.out.print("* ");
}
else
System.out.print(" ");
}
System.out.println();
}
}
}

Answer

This is the logic in the following code:

  • Loop over each row of the output (so from 0 to n excluded so that we have n rows)
  • Loop over each column of the output (so from 0 to n excluded so that we have n columns)
  • We need to print a * only when it is the first row (x == 0) or the last row (x == n - 1) or the column is in the opposite diagonal (column == n - 1 - row)

Code:

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.print("Enter a number: ");
    int n = input.nextInt();
    for (int row = 0; row < n; row++) {
        for (int column = 0; column < n; column++) {
            if (row == 0 || row == n - 1 || column == n - 1 - row) {
                System.out.print("*");
            } else {
                System.out.print(" ");
            }
        }
        System.out.println();
    }
}

Sample output for n = 6:

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

(Note that this output has trailing white-spaces for each row, you did not specify whether they should be included, but it is easy to remove them by adding another check).

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