Python program to print a mirrored right-angle star triangle

Introduction:

In this post, we will learn how to print a mirrored right-angle triangle pattern in Python. For this example, I will use star (*) to print the pattern but you can also use any other character to print that.

The final output will look as like below:

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

It looks complex but actually it is easy. Let me explain to you a bit more:

How to write the program:

Let’s take a look at the below pattern:

#  #  #  #  *  
#  #  #  *  *  
#  #  *  *  *  
#  *  *  *  *  
*  *  *  *  *

Can we print this ?

  • It’s height or size is 5
  • For row 1, we are printing 5 - 1 = 4 # and one *
  • For row 2, we are printing 5 - 2 = 3 # and two *
  • For row 3, we are printing 5 - 3 = 2 # and three *

Easy ?

So, if you print one blank space ’ ’ instead of ’#‘, you will get the above mirrored right angle triangle. Just write two loops and use the above logic 🙂

Using for loop:

Below is the program that uses for loop to print the mirrored right angle triangle pattern in python:

height = int(input("Enter the height of the triangle : "))

for i in range(1, height + 1):
    for j in range(1, height + 1):
        if(j <= height - i):
            print(' ', end = '  ')
        else:
            print('*', end = '  ')
    print()
  • We are taking the height of the triangle as input from the user and storing it in height variable.
  • We have two for loops. The outer loop is for the rows of the triangle and inner loop is for the columns of the triangle.
  • i is used for the outer loop and j is for the inner loop. We are checking if j is less than or equal to height - i, we are printing a blank space and else we are printing ***.

Sample Output:

Enter the height of the triangle : 5
            *  
         *  *  
      *  *  *  
   *  *  *  *  
*  *  *  *  *

Enter the height of the triangle : 10
                           *  
                        *  *  
                     *  *  *  
                  *  *  *  *  
               *  *  *  *  *  
            *  *  *  *  *  *  
         *  *  *  *  *  *  *  
      *  *  *  *  *  *  *  *  
   *  *  *  *  *  *  *  *  *  
*  *  *  *  *  *  *  *  *  *

Python program to print a Mirrored right angle triangle star pattern

Writing the same program using while loop:

height = int(input("Enter the height of the triangle : "))

i = 1

while(i < height + 1):
    j = 1
    while(j < height + 1):
        if(j <= height - i):
            print(' ', end = '  ')
        else:
            print('*', end = '  ')
        j = j + 1
    i = i + 1
    print()

This program is same as the previous one. The only difference is the place we are initializing the variables i and j.

  • Before starting the program, we are initializing i as 1.
  • In the outer while loop, we are initializing j as 1 before starting the inner while loop.

This program will print similar output.

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