C Program To Print Hollow Star Pyramid

Here, we will print the hollow star pyramid pattern using a C program.

Input: 

n = 5 

Output: 

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

C

// C Program to Demonstrate
// a Hollow Star Pyramid
#include <stdio.h>

int main()
{
    int i, space, n = 5, j = 0;

    // first for loop is used to
    // iterate number of rows
    for (i = 0; i < n - 1; i++) {

        // second for loop is used to print spaces
        for (space = 1; space < n - i; space++) {
            printf(" ");
        }
        // third for loop is used
        // to print the required
        // pattern
        for (j = 0; j <= 2 * i; j++) {
            if (j == 0 || j == 2 * i)
                printf("*");
            else
                printf(" ");
        }
        // print the new line after every row
        printf("\n");
    }
    // used to print last row
    for (i = 0; i < 2 * n - 1; i++) {
        printf("*");
    }
    return 0;
}

Output

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

Time Complexity: O(n^2) for given input n

Auxiliary Space: O(1)