C Program For Printing Inverted Pyramid

Here, we will see how to print an inverted pyramid using a C program. Below are the examples:

Input: 8
Output:

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

Input: 5
Output:

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

Method 1:

The pattern would be divided into three parts:

1. A for loop will be used to print the blank spaces
2. A for loop will be used to print the triangle from the left-hand side
3. A for loop will be used to print the rest of the triangle, making the exact pattern

Algorithm:

1. Initialize variables i, j, and space for rows, columns, and blank spaces, respectively.

2. The number of rows here is 8, the user can take any number.

3. Initialize a for loop that will work as the main loop in printing the pattern and drive the other loops inside it.

4. Initialize a for loop that will print the blank spaces inside the main loop.

5. Now, in order to print the star pattern, we will first print the half pyramid as shown below. To do that, we will initialize a for loop with the condition given as 2 * i – 1, because the number of stars is odd.

6. After it, we’ll use another for loop to print the rest of the pattern.

Below is the C program to print an inverted pyramid pattern:

C

// C program to print
// inverted pyramid
// pattern
#include <stdio.h>

// Driver code
int main()
{
   int rows = 8, i, j, space;

   for (i = rows; i >= 1; --i)
   {
       // Loop to print the blank space
       for (space = 0;
            space < rows - i; ++space)
           printf("  ");

       // Loop to print the half of
       // the star triangle
       for (j = i; j <= 2 * i - 1; ++j)
           printf("* ");

       // Loop to print the rest of
       // the star triangle
       for (j = 0; j < i - 1; ++j)
           printf("* ");
       printf("\n");
   }

   return 0;
}

Output

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

Time Complexity: O(n²)

Auxiliary Space: O(1)

Method 2:

Two for loops will be used:

1. A for loop will be used to print the blank spaces
2. A for loop will be used to print the stars

Algorithm:

1. Initialize variables i, j, and rows.
2. The number of rows here is 8, the user can take any number.
3. Initialize a for loop that will work as the main loop in printing the pattern and drive the other loops inside it.
4. Initialize a for loop that will print the blank spaces inside the main loop and will run from 1 to i.
5. Run a for loop from 1 to rows * 2 – (i * 2 – 1), to print the stars.
6. Move to the next line with the help of the new line character.

Below is the C program to print an inverted pyramid pattern:

C

// C program to print
// inverted pyramid
// pattern
#include <stdio.h>

// Driver code
int main()
{
    int i, j, rows = 8;

    for (i = 1; i <= rows; i++)
    {
        // Loop to print the blank spaces
        for (j = 1; j < i; j++)
        {
            printf(" ");
        }

        // Loop to print the stars
        for (j = 1;
             j <= (rows * 2 - (2 * i - 1));
             j++)
        {
            printf("*");
        }

        // Move to the next line to
        // complete the pattern
        printf("\n");
    }

    return 0;
}

Output

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

Time Complexity: O(n²)

Auxiliary Space: O(1)