#What is the largest integer whose digits are all different (and do not include 0) that is divisible by each of its individual digits?
#Requirements:
# -- Integer
# -- Digits all different (largest possible would be 987654321)
# -- Divisible by each of individual digits
# note: 
#    this integer cannot contain the digit 5 if it also contains any even digit, 
#    because then the number would be divisible by 10, and the last digit would be 0
#    similarly, if the last digit is odd, it can't contain any other even digit.

use strict;
use warnings;

my $max_number = 987654321;
#my $max_number = 10000;
foreach ( 0 .. $max_number - 1 ) {
	my $test_number = $max_number - $_;
	print "number / 100000: " . $test_number/100000 . "\n" if $test_number % 100000 == 0;
	if ( passes($test_number) ) {
		print "$test_number passes!\n"; 
		die;
	}
}

sub passes {
	my $test_number = shift() || die "no test number";
	my @digits = split("", $test_number);
	my %seen;
	my $last_digit;

	#fail if see the same digit twice.
	foreach (  @digits ) {
		return 0 if $_ == 0; #fail if contains 0
		return 0 if $seen{$_};
		$seen{$_} = 1;
	}
	#set the last digit
	$last_digit = $digits[$#digits];

	#fail if contains 5, and any other digit is even
	#or the last digit is 1, and any other digit is even 
	if ( $seen{5} || $last_digit % 2 == 1 ) {
		for ( qw(2 4 6 8) ) {
			return 0 if $seen{$_}; 
		}		
	}

	for ( keys %seen ) {
		return 0 unless $test_number % $_ == 0 ;
	}
	return 1;
}