Star patterns set 2

Star patterns set 2
Star patterns set 2

Problem solving is the best way achieve a good programming logic, In coding interview interviewer may ask you print any number pattern , alphabet pattern or an character patterns. We recommend you to follow our patterns series so you will feel comfortable with printing patterns. In this blog post you will find set 2 of star patterns.

We recommend you to solve other types patterns as well –

 Click on the pattern and you will get redirected to the code.

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

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

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

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

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

Pattern 1

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

Code for pattern 1

Pattern 2

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

Code for pattern 2

Pattern 3

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

Code for pattern 3

Pattern 4

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

Code for pattern 4

Pattern 5

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

Code for pattern 5

How the patterns in set 2 work

Set 2 moves from left-aligned shapes to right-aligned triangles and centered pyramids. The new idea is that each row has two parts: leading spaces first, then the stars. If you print the spaces correctly, the stars line up on their own.

Logic for each pattern

  • Pattern 1, right-aligned triangle: in row i (starting at 1) print n - i spaces and then i stars.
  • Pattern 2, right-aligned inverted triangle: the reverse. Row 1 has no spaces and 5 stars, and each next row has one more space and one star less.
  • Pattern 3, left-pointing half diamond: print the right-aligned triangle from 1 to 5 stars, then continue with the inverted one from 4 stars down to 1.
  • Pattern 4, pyramid with spaced stars: print n - i spaces, then print a star followed by a space i times. The extra space between stars gives the open look.
  • Pattern 5, solid pyramid: print n - i spaces and then 2 * i - 1 stars, so the rows have 1, 3, 5, 7 and 9 stars.

Pyramid code in Java

int n = 5;
for (int i = 1; i <= n; i++) {
    for (int s = 1; s <= n - i; s++) {
        System.out.print(' ');          // leading spaces
    }
    for (int k = 1; k <= 2 * i - 1; k++) {
        System.out.print('*');          // stars: 1, 3, 5, 7, 9
    }
    System.out.println();
}

Things to remember

  • For a centered shape, the number of spaces goes down by one each row while the number of stars goes up (by 1 for a right-aligned triangle, by 2 for a pyramid).
  • Spaces are part of the output. If your stars are not aligned, check the space loop first.
  • The time complexity is O(n²) and the extra space is O(1).

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