Why do we print spaces in the middle?

Spaces keep the left and right halves aligned so the pattern looks symmetric. Without spaces, the right half would shift left.

How do we build the mirror part?

After printing 1..i on the left, we loop from 5 down to 1 and print either a space (when k > i) or k (when k <= i).

What is the time complexity?

O(n^2) for n rows because we run fixed-width inner loops for each row.

Mirrored Number Pattern in C#

Q: What is the time complexity?

O(n^2) for n rows because we run fixed-width inner loops for each row.

Beginner

⏱️ 7 min read

📚 Updated: Aug 2025

🎯 2 Code Examples

Nested Loops

Mirrored number pattern output (1..i then i..1) in C# programming

What You’ll Learn

How to print a mirrored number pattern where the left side increases (1..i) and the right side decreases (i..1). Spaces in the middle keep the mirror aligned.

⭐ Pattern Output

For rows = 5, the pattern looks like this:

Output

Complete C# Program

This follows the reference approach exactly: one loop prints the left half (or spaces), and another loop prints the right half (or spaces).

using System;

namespace MyApp
{
    class Program
    {
        static void Main(string[] args)
        {
            int i, j, k;

            for (i = 1; i <= 5; i++)
            {
                for (j = 1; j <= 5; j++)
                {
                    if (j <= i)
                        Console.Write(j);
                    else
                        Console.Write(" ");
                }

                for (k = 5; k >= 1; k--)
                {
                    if (k > i)
                        Console.Write(" ");
                    else
                        Console.Write(k);
                }

                Console.WriteLine();
            }
        }
    }
}

Variation — User Input rows

Same idea, but make the height configurable:

using System;

namespace MyApp
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Enter rows: ");
            int rows = Convert.ToInt32(Console.ReadLine());
            if (rows < 1) return;

            for (int i = 1; i <= rows; i++)
            {
                for (int j = 1; j <= rows; j++)
                    Console.Write((j <= i) ? j.ToString() : " ");

                for (int k = rows; k >= 1; k--)
                    Console.Write((k > i) ? " " : k.ToString());

                Console.WriteLine();
            }
        }
    }
}