/* 

  tak benchmark in Picat v3.

  bench/tak.pl
  https://github.com/SWI-Prolog/bench

  Changes:
  - added output in tak/0.

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

*/

main => go.


go ?=>
  tak(18,12,6,X),
  println(X),
  
  nl.

go => true.

% """
% generated: 17 November 1989
% option(s): SOURCE_TRANSFORM_1
%
%   tak
%
%   Evan Tick (from Lisp version by R. P. Gabriel)
%
%   (almost) Takeuchi function (recursive arithmetic)
% """

top:-tak.

tak :- tak(18,12,6,_).

tak(X,Y,Z,A) :-
        X =< Y,
        Z = A.
tak(X,Y,Z,A) :-
	X > Y,
        X1 is X - 1,
        tak(X1,Y,Z,A1),
        Y1 is Y - 1,
        tak(Y1,Z,X,A2),
        Z1 is Z - 1,
        tak(Z1,X,Y,A3),
        tak(A1,A2,A3,A).