C++ Program to Print the Pattern ‘G”

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’: 

Graphical Representation of G Pattern

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 columns, 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.

Example:

C

// C program to print the pattern G
#include <stdio.h>

void pattern(int line)
{
    int i, j;
    for (i = 0; i < line; i++) {
        for (j = 0; j < line; j++) {
            if ((j == 1 && i != 0 && i != line - 1)
                || ((i == 0 || i == line - 1) && j > 1
                    && j < line - 2)
                || (i == ((line - 1) / 2) && j > 2
                    && j < line - 1)
                || (j == line - 2 && i != 0
                    && i >= ((line - 1) / 2)
                    && i != line - 1))
                printf("*");
            else
                printf(" ");
        }
        printf("\n");
    }
}
int main()
{
    int line = 7;
    pattern(line);
    return 0;
}

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.