C# Program to Print Pyramid Pattern

Use nested for loops in C# where the outer loop controls the rows and the inner loops print spaces and stars; for example, for (int i = 1; i <= n; i++) { for (int j = n - i; j > 0; j--) Console.Write(" "); for (int k = 0; k < 2 * i - 1; k++) Console.Write("*"); Console.WriteLine(); } prints a pyramid of height n.

Examples

Input3

Output * *** *****

Input5

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

Input1

Output*

How to Think About It

To print a pyramid pattern, think of each row as having some spaces followed by stars. The number of spaces decreases as you go down, and the number of stars increases. Use one loop to go through each row, then inside it, print spaces first, then stars.

Algorithm

1

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

2

For each row from 1 to height:

3

Print (height - current row) spaces.

4

Print (2 * current row - 1) stars.

5

Move to the next line.

6

Repeat until all rows are printed.

Code

csharp

using System;
class Program {
    static void Main() {
        int n = 5;
        for (int i = 1; i <= n; i++) {
            for (int j = n - i; j > 0; j--) Console.Write(" ");
            for (int k = 0; k < 2 * i - 1; k++) Console.Write("*");
            Console.WriteLine();
        }
    }
}

Output

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

Dry Run

Let's trace the pyramid printing for n=3 through the code.

1

Row 1

Print 2 spaces and 1 star: " *"

2

Row 2

Print 1 space and 3 stars: " ***"

3

Row 3

Print 0 spaces and 5 stars: "*****"

Row	Spaces	Stars	Output
1	2	1	*
2	1	3	***
3	0	5	*****

Why This Works

Step 1: Outer loop controls rows

The outer for loop runs from 1 to n, each iteration prints one row of the pyramid.

Step 2: Print spaces first

For each row, print n - i spaces to align stars in the center.

Step 3: Print stars next

Print 2 * i - 1 stars to form the pyramid shape.

Alternative Approaches

Using while loops

csharp

using System;
class Program {
    static void Main() {
        int n = 5, i = 1;
        while (i <= n) {
            int j = n - i;
            while (j > 0) { Console.Write(" "); j--; }
            int k = 0;
            while (k < 2 * i - 1) { Console.Write("*"); k++; }
            Console.WriteLine();
            i++;
        }
    }
}

This uses while loops instead of for loops; functionally the same but slightly longer.

Using string.PadLeft and string.PadRight

csharp

using System;
class Program {
    static void Main() {
        int n = 5;
        for (int i = 1; i <= n; i++) {
            string stars = new string('*', 2 * i - 1);
            Console.WriteLine(stars.PadLeft(n + i - 1));
        }
    }
}

This uses built-in string padding methods to simplify space printing.

Complexity: O(n^2) time, O(1) space

Time Complexity

The program uses nested loops: the outer loop runs n times and the inner loops run up to n times, resulting in O(n^2) time.

Space Complexity

Only a few variables are used; no extra space grows with input size, so space complexity is O(1).

Which Approach is Fastest?

All approaches have similar time complexity; using string padding may be more readable but not faster.

Approach	Time	Space	Best For
For loops	O(n^2)	O(1)	Clear control of spaces and stars
While loops	O(n^2)	O(1)	Alternative syntax, same performance
String padding	O(n^2)	O(1)	Simpler code, less manual space printing