hanoi.sd7

(********************************************************************)
(*                                                                  *)
(*  hanoi.sd7     Solve the tower of hanoi problem                  *)
(*  Copyright (C) 1991, 1992, 1993, 1994, 2004  Thomas Mertes       *)
(*                                                                  *)
(*  This program is free software; you can redistribute it and/or   *)
(*  modify it under the terms of the GNU General Public License as  *)
(*  published by the Free Software Foundation; either version 2 of  *)
(*  the License, or (at your option) any later version.             *)
(*                                                                  *)
(*  This program is distributed in the hope that it will be useful, *)
(*  but WITHOUT ANY WARRANTY; without even the implied warranty of  *)
(*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the   *)
(*  GNU General Public License for more details.                    *)
(*                                                                  *)
(*  You should have received a copy of the GNU General Public       *)
(*  License along with this program; if not, write to the           *)
(*  Free Software Foundation, Inc., 51 Franklin Street,             *)
(*  Fifth Floor, Boston, MA  02110-1301, USA.                       *)
(*                                                                  *)
(********************************************************************)


$ include "seed7_05.s7i";
  include "stdio.s7i";


const proc: hanoi (in integer: disk, in string: source, in string: dest, in string: via) is func
  begin
    if disk > 0 then
      hanoi(pred(disk), source, via, dest);
      writeln("Move disk " <& disk <& " from " <& source <& " to " <& dest);
      hanoi(pred(disk), via, dest, source);
    end if;
  end func;


const proc: hanoi (in integer: height) is func
  begin
    writeln("To move a tower of height " <& height <& " from left to right:");
    writeln;
    hanoi(height, "left", "right", "middle");
    writeln;
  end func;


const proc: main is func
  begin
    writeln;
    writeln("Tower of Hanoi:");
    writeln;
    hanoi(4);
  end func;