In this article, we will learn how to print the pattern G using stars and white-spaces. Given a number n, we will write a program to print the pattern G over n lines or rows.

Examples: 

Input : 7
Output :
  ***  
 *     
 *     
 * *** 
 *   * 
 *   * 
  ***  

Input : 9
Output :
  *****  
 *       
 *       
 *       
 *   *** 
 *     * 
 *     * 
 *     * 
  *****  

 

In this program, we have used the simple logic of iteration over lines to create the pattern G. Please look at the image below which represents the pattern G in the form of a 2-d matrix, where mat[i][j] = ‘ij’: 
 

If we try to analyze this picture with a (row, column) matrix and the circles represent the position of stars in the pattern G, we will learn the steps. Here we are performing the operations column-wise. So for the first line of stars, we set the first if condition, where the row position with 0 and (n-1) won’t get the stars and all other rows from 1 to (n-1), will get the stars. Similarly, for the second, third and fourth column we want stars at the position row = 0 and row = (n-1). The other steps are self-explanatory and can be understood from the position of rows and columns in the diagram.
Below is the implementation of above idea: 
 

Output: 

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

Time Complexity: O(n²), where n represents the given input.
Auxiliary Space: O(1), no extra space is required, so it is a constant.

Please refer complete article on Program to print the pattern ‘G’ for more details!