Question

I was wondering how to create triangle out of asterisks on its tip rather than on its base.

I have the code for making it stand on its base:

    public static String printTriangle (int count) 
{
    if( count <= 0 ) return "";

    String p = printTriangle(count - 1);
    p = p + "*";
    System.out.print(p);
    System.out.print("\n");

    return p;
 }

But then I’m stuck on how to have the greatest number of stars on the top, and then the next least, and so on. I was thinking something along the terms of having (count – p) to have the input of rows be subtracted from the amount of decrease, but then i was confused by this idea because p is string.

EDIT: I tried changing the position of printTriangle(count – 1) using my original method without iterations and got 1 star per each line; how can I fix this?

public class triangles 
{
public static void main(String[] args)
{
    printTriangle(5);
}
public static String printTriangle (int count) 
{
    if( count <= 0 ) return "";
      String p = "";
    p = p + "*";
    System.out.print(p);
    System.out.print("\n");
     p = printTriangle(count - 1);
    return p;

         }


}

Answer 1

To me it looks like you are missing a loop inside the recursive function to add the correct number on *s for each line.

  public static String printTriangle (int count) 
  {
      if( count <= 0 ) return "";

      String p = printTriangle(count - 1);
      for (int i=0; i<count; i++)
      {
        p = p + "*";
      }

      p += "\n";
      return p;
   }

and calling code to look like

String triangle = printTriangle(4);
System.out.println(triangle);

it produces

*
**
***
****

Also I would use a StringBuilder and not a string for this purpose.

Just reread you question.

in you were after a triangle like this

****
***
**
*

You need to change when recursion is called.

ie

  public static String printTriangle (int count) 
  {
      if( count <= 0 ) return "";

      String p="";
      for (int i=0; i<count; i++)
      {
        p = p + "*";
      }

      p += "\n";
      return p + printTriangle(count - 1);
   }