Re: Puzzle: What is the largest integer whose digits are all different (and do not include 0) that is divisible by each of its individual digits?


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Re: Puzzle: What is the largest integer whose digits are all different (and do not include 0) that is divisible by each of its individual digits?

by Skeeve (Parson)

on Oct 27, 2005 at 13:59 UTC ( [id://503336]=note: print w/replies, xml )

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in reply to Puzzle: What is the largest integer whose digits are all different (and do not include 0) that is divisible by each of its individual digits?

My attempt:

#!/usr/bin/perl
use strict;
use warnings;

my @digits= qw(9 8 7 6 5 4 3 2 1);
my $max= 0;

permut('', @digits);
print "Solution: $max\n";

sub permut {
    my ($s, @digits)= @_;
    my $i= scalar @digits;
    DIV: {
        { no warnings;
            last DIV if $s<$max;
        }
        foreach my $i (split //m,$s) {
            last DIV if $s % $i;
        }
        print "$s\n";
        $max=$s;
    }
    if ($i) {
        while ($i--) {
            my $f= shift @digits;
            permut($s.$f, @digits);
            push(@digits, $f);
        }
    }
}
[download]

My solution and the time needed on a 900MHz Power PC G3 with 640MB and lot's of Java running in the background ;-) is:
9867312 real 2m14.144s user 0m32.100s sys 0m0.730s

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e