/*

  Sierpinski triangle in Picat.

  From
  http://rosettacode.org/wiki/Sierpinski_triangle
  """
  Produce an ASCII representation of a Sierpinski triangle of order N. 
  For example, the Sierpinski triangle of order 4 should look like this:

                       *
                      * *
                     *   *
                    * * * *
                   *       *
                  * *     * *
                 *   *   *   *
                * * * * * * * *
               *               *
              * *             * *
             *   *           *   *
            * * * *         * * * *
           *       *       *       *
          * *     * *     * *     * *
         *   *   *   *   *   *   *   *
        * * * * * * * * * * * * * * * *
  """

  Model created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/


main => go.

go =>
   foreach(N in 1..4)
      sierpinski(N),
      nl
   end,

   nl.

% Inspired the E solution
sierpinski(N)  =>
    Size = 2**N,
    foreach(Y in Size-1..-1..0)
       printf("%s", [' ' : _I in 1..Y]),
       foreach(X in 0..Size-Y-1)
          printf("%s ", cond(X /\ Y == 0, "*", " ")) 
       end,
       nl
    end.