PowerShell Script to Print Pyramid Pattern

Use a nested loop in PowerShell like for ($i=1; $i -le $n; $i++) { " " * ($n - $i) + "* " * $i } to print a pyramid pattern with stars.

Examples

Input3

Output * * * * * *

Input5

Output * * * * * * * * * * * * * * *

Input1

Output*

How to Think About It

To print a pyramid pattern, think of each line as having spaces followed by stars. The number of spaces decreases each line, while the stars increase. Use loops to print spaces first, then stars, for each line.

Algorithm

1

Get the number of rows (n) from the user.

2

For each line from 1 to n:

3

Print (n - current line) spaces.

4

Print (current line) stars with spaces.

5

Move to the next line.

Code

powershell

param([int]$n = 5)
for ($i = 1; $i -le $n; $i++) {
    $spaces = ' ' * ($n - $i)
    $stars = '* ' * $i
    Write-Output "$spaces$stars"
}

Output

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

Dry Run

Let's trace printing a pyramid with 3 rows through the code

1

First line

i=1, spaces = 3-1=2 spaces, stars = 1 star: ' * '

2

Second line

i=2, spaces = 3-2=1 space, stars = 2 stars: ' * * '

3

Third line

i=3, spaces = 3-3=0 spaces, stars = 3 stars: '* * * '

Line	Spaces	Stars	Output
1	2	1	*
2	1	2	* *
3	0	3	* * *

Why This Works

Step 1: Calculate spaces

We print n - i spaces to align stars in a pyramid shape.

Step 2: Print stars

We print i stars with spaces to form the pyramid's width.

Step 3: Loop through lines

Repeating for each line builds the pyramid from top to bottom.

Alternative Approaches

Using Write-Host with -NoNewline

powershell

param([int]$n=5)
for ($i=1; $i -le $n; $i++) {
    for ($j=1; $j -le $n - $i; $j++) { Write-Host -NoNewline ' ' }
    for ($k=1; $k -le $i; $k++) { Write-Host -NoNewline '* ' }
    Write-Host ''
}

This method prints directly without building strings, giving more control but more code.

Using string formatting

powershell

param([int]$n=5)
for ($i=1; $i -le $n; $i++) {
    $line = '{0}{1}' -f (' ' * ($n - $i)), ('* ' * $i)
    Write-Output $line
}

Uses string format operator for clearer string construction but slightly less intuitive.

Complexity: O(n^2) time, O(n) space

Time Complexity

The outer loop runs n times, and each inner string multiplication runs up to n times, resulting in O(n^2) time.

Space Complexity

Each line creates strings proportional to n, so space is O(n) for the output line.

Which Approach is Fastest?

Building strings with multiplication is efficient and readable; using Write-Host with loops is more verbose but similar in speed.

Approach	Time	Space	Best For
String multiplication	O(n^2)	O(n)	Readability and simplicity
Write-Host loops	O(n^2)	O(1)	Direct output control
String formatting	O(n^2)	O(n)	Clear string construction