Python Program to Print Diamond Pattern

You can print a diamond pattern in Python using nested for loops to print spaces and stars in the right order, for example: for i in range(n): print(' '*(n-i-1) + '*'*(2*i+1)) for the top half and similarly for the bottom half.

Examples

Input3

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

Input5

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

Input1

Output*

How to Think About It

To print a diamond pattern, first print the top half with increasing stars centered by spaces, then print the bottom half with decreasing stars also centered. Use loops to control the number of spaces and stars on each line.

Algorithm

1

Get input number n for diamond size

2

For each line i from 0 to n-1, print (n-i-1) spaces and (2*i+1) stars

3

For each line i from n-2 down to 0, print (n-i-1) spaces and (2*i+1) stars

4

End

Code

python

n = int(input('Enter diamond size: '))
for i in range(n):
    print(' ' * (n - i - 1) + '*' * (2 * i + 1))
for i in range(n - 2, -1, -1):
    print(' ' * (n - i - 1) + '*' * (2 * i + 1))

Output

Enter diamond size: 3
  *
 ***
*****
 ***
  *

Dry Run

Let's trace input 3 through the code

1

Top half loop i=0

Print 2 spaces and 1 star: ' *'

2

Top half loop i=1

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

3

Top half loop i=2

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

4

Bottom half loop i=1

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

5

Bottom half loop i=0

Print 2 spaces and 1 star: ' *'

i	Spaces	Stars	Line Printed
0	2	1	*
1	1	3	***
2	0	5	*****
1	1	3	***
0	2	1	*

Why This Works

Step 1: Print top half

The first loop prints lines with increasing stars centered by spaces using print(' ' * (n - i - 1) + '*' * (2 * i + 1)).

Step 2: Print bottom half

The second loop prints lines with decreasing stars in reverse order to complete the diamond shape.

Step 3: Center alignment

Spaces before stars ensure the diamond is centered horizontally.

Alternative Approaches

Using while loops

python

n = int(input('Enter diamond size: '))
i = 0
while i < n:
    print(' ' * (n - i - 1) + '*' * (2 * i + 1))
    i += 1
i = n - 2
while i >= 0:
    print(' ' * (n - i - 1) + '*' * (2 * i + 1))
    i -= 1

Uses while loops instead of for loops; slightly longer but same logic.

Using string center method

python

n = int(input('Enter diamond size: '))
width = 2 * n - 1
for i in range(n):
    print(('*' * (2 * i + 1)).center(width))
for i in range(n - 2, -1, -1):
    print(('*' * (2 * i + 1)).center(width))

Uses string <code>center()</code> method for cleaner alignment.

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

Time Complexity

The program uses two loops each running about n times, and each line prints up to 2n-1 characters, so overall time is O(n^2).

Space Complexity

Only a few variables are used and output is printed directly, so space is O(1).

Which Approach is Fastest?

All approaches have similar time complexity; using center() may improve readability but not speed.

Approach	Time	Space	Best For
For loops with spaces	O(n^2)	O(1)	Simple and clear
While loops	O(n^2)	O(1)	Alternative loop style
String center method	O(n^2)	O(1)	Cleaner alignment