C# Program to Print Number Pattern

You can print a number pattern in C# using nested for loops like for (int i = 1; i <= n; i++) { for (int j = 1; j <= i; j++) { Console.Write(j + " "); } Console.WriteLine(); } to print numbers in increasing order per line.

Examples

Input3

Output1 1 2 1 2 3

Input5

Output1 1 2 1 2 3 1 2 3 4 1 2 3 4 5

Input1

Output1

How to Think About It

To print a number pattern, think of rows and columns. For each row from 1 to n, print numbers starting from 1 up to the current row number. Use one loop for rows and a nested loop for printing numbers in each row.

Algorithm

1

Get the number of rows n from the user

2

For each row i from 1 to n, do:

3

For each number j from 1 to i, print j followed by a space

4

After inner loop ends, print a new line

5

End

Code

csharp

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

Output

1 
1 2 
1 2 3 
1 2 3 4 
1 2 3 4 5 

Dry Run

Let's trace the program for n=3 to see how it prints the pattern.

1

Start outer loop with i=1

Inner loop runs j=1 to 1, prints '1 '

2

Print newline after inner loop

Output so far: 1

3

Outer loop i=2

Inner loop j=1 to 2, prints '1 2 '

4

Print newline

Output so far: 1 1 2

5

Outer loop i=3

Inner loop j=1 to 3, prints '1 2 3 '

6

Print newline

Final output: 1 1 2 1 2 3

i (row)	j (column)	Printed Numbers
1	1	1
2	1-2	1 2
3	1-3	1 2 3

Why This Works

Step 1: Outer loop controls rows

The outer for loop runs from 1 to n, each iteration represents a new line in the pattern.

Step 2: Inner loop prints numbers

The inner for loop prints numbers from 1 up to the current row number, creating the pattern.

Step 3: New line after each row

After printing numbers for a row, Console.WriteLine() moves to the next line for the next row.

Alternative Approaches

Using while loops

csharp

using System;
class Program {
    static void Main() {
        int n = 5;
        int i = 1;
        while (i <= n) {
            int j = 1;
            while (j <= i) {
                Console.Write(j + " ");
                j++;
            }
            Console.WriteLine();
            i++;
        }
    }
}

While loops achieve the same result but are less concise than for loops for counting.

Printing pattern in reverse order

csharp

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

This prints the pattern starting from the largest row down to 1, reversing the pattern.

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

Time Complexity

The nested loops run approximately n*(n+1)/2 times, which is O(n^2), because for each row i, the inner loop runs i times.

Space Complexity

The program uses constant extra space, only variables for counters, so O(1) space.

Which Approach is Fastest?

Using for loops is generally faster and clearer than while loops for counting patterns; reversing the pattern changes output but not complexity.

Approach	Time	Space	Best For
Nested for loops	O(n^2)	O(1)	Simple and clear pattern printing
Nested while loops	O(n^2)	O(1)	Same complexity, less concise
Reverse pattern with for loops	O(n^2)	O(1)	Printing pattern in reverse order