C++ Program to Print Pyramid Pattern

You can print a pyramid pattern in C++ using nested for loops 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) cout << ' '; for (int k = 1; k <= 2 * i - 1; ++k) cout << '*'; cout << '\n'; } 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.

Code

cpp

#include <iostream>
using namespace std;

int main() {
    int n;
    cout << "Enter pyramid height: ";
    cin >> n;

    for (int i = 1; i <= n; ++i) {
        for (int j = n - i; j > 0; --j) cout << ' ';
        for (int k = 1; k <= 2 * i - 1; ++k) cout << '*';
        cout << '\n';
    }
    return 0;
}

Output

Enter pyramid height: 5
    *
   ***
  *****
 *******
*********

Dry Run

Let's trace the pyramid pattern for input 3 through the code

1

Input

User enters n = 3

2

Row 1

Print 2 spaces, then 1 star: ' *'

3

Row 2

Print 1 space, then 3 stars: ' ***'

4

Row 3

Print 0 spaces, then 5 stars: '*****'

Row (i)	Spaces (n - i)	Stars (2*i - 1)
1	2	1
2	1	3
3	0	5

Why This Works

Step 1: Outer loop controls rows

The for loop with variable i runs from 1 to n, each iteration prints one row.

Step 2: Print spaces first

For each row, print n - i spaces to align stars in pyramid shape.

Step 3: Print stars next

Then print 2 * i - 1 stars to form the pyramid's width for that row.

Alternative Approaches

Using while loops

cpp

#include <iostream>
using namespace std;

int main() {
    int n, i = 1;
    cout << "Enter pyramid height: ";
    cin >> n;

    while (i <= n) {
        int spaces = n - i;
        while (spaces > 0) {
            cout << ' ';
            spaces--;
        }
        int stars = 2 * i - 1;
        while (stars > 0) {
            cout << '*';
            stars--;
        }
        cout << '\n';
        i++;
    }
    return 0;
}

This uses while loops instead of for loops, which some beginners find easier to understand but is slightly longer.

Using recursion

cpp

#include <iostream>
using namespace std;

void printPyramid(int n, int i = 1) {
    if (i > n) return;
    for (int j = n - i; j > 0; --j) cout << ' ';
    for (int k = 1; k <= 2 * i - 1; ++k) cout << '*';
    cout << '\n';
    printPyramid(n, i + 1);
}

int main() {
    int n;
    cout << "Enter pyramid height: ";
    cin >> n;
    printPyramid(n);
    return 0;
}

This recursive approach prints the pyramid by calling the function for each row, which is elegant but less common for beginners.

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 2*n times in total per row, resulting in O(n^2) time.

Space Complexity

Only a few variables are used; no extra data structures, so space complexity is O(1).

Which Approach is Fastest?

All approaches have similar time complexity; iterative for-loop method is simplest and most readable.

Approach	Time	Space	Best For
For loops	O(n^2)	O(1)	Simplicity and readability
While loops	O(n^2)	O(1)	Beginners preferring while syntax
Recursion	O(n^2)	O(n) due to call stack	Demonstrating recursion concepts