#!/usr/bin/ruby -w =begin /*************************************************************************** * Copyright (C) 2008 by Paul Lutus * * lutusp@arachnoid.com * * * * 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., * * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * ***************************************************************************/ =end def monty_test(switch_doors) # put the prize behind a random door prize = rand(3) # the contestant's random choice choice = rand(3) win = false if(switch_doors) # the teaser "Monty door" must be neither the # contestant's choice nor the winning door monty_door = 0 monty_door += 1 while (monty_door == choice || monty_door == prize) # the contestant's new choice must not be # his existing choice nor the Monty door new_choice = 0 new_choice += 1 while (new_choice == choice || new_choice == monty_door) win = (new_choice == prize) else # don't switch doors win = (choice == prize) end return win end def monty_game(max,switch_doors) if(switch_doors) print "Switching doors: " else print "Not switching doors: " end score = 0 1.upto(max) do score += 1 if monty_test(switch_doors) end result = score.to_f / max.to_f puts "win probability #{result}" end puts "Monty Hall Problem:" max = 100000 monty_game(max,true) monty_game(max,false)