#!/usr/bin/perl

use strict;
use warnings;

my $iteration = 10000;
my $change_choice = 0;

print "\n";
print modelingMontyHall($change_choice);
print "\n";

sub modelingMontyHall {
	my $change_choice = shift;
	my $success_counter = 0;
	my ( $i, $j );
	my @doors; # 0 - animal, 1 - car
	my $gamer_choice;
	my $showman_open_door;
	my $result = 0;
	my $success_door;

	if ($change_choice) {print "Gamer change choice\n"} else {print "Gamer NOT change choice\n"};

	for ( $i = 0 ; $i < $iteration ; $i++ ) {

		# Preparing
		@doors = ( 0, 0, 0 );
		$success_door = int( rand() * 3 );
		$doors[$success_door] = 1; # door with car

		# First step
		$gamer_choice = 0;
		for ( $j = 0 ; $j < 3 ; $j++ ) {
			if ( ( $j != $gamer_choice ) and ( $doors[$j] == 0 ) ) {
				$showman_open_door = $j;
				last;
			}
		}

		# Second step
		if ($change_choice) {
			for ( $j = 0 ; $j < 3 ; $j++ ) {
				if ( ( $j != $gamer_choice ) and ( $j != $showman_open_door ) ) {
					$gamer_choice = $j;
					last;
				}
			}
		}

		# Count result
		if ( $doors[$gamer_choice] ) {
			$result++;
		}
	}
	return $result;
}