Re: list of four digit lock combinations without repeated digits

[sundialsvc4]

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[Lotus1]

I converted this pseudo code to Perl and found that it produces the 5040 permutations.

use warnings;
use strict;

my @digits_used;
#$digits_used = [false x 10];
find_digits(1, 0);  #// get the ball rolling

sub find_digits {
    my ($depth, $total) = @_;
    for my $digit (0..9) {
        if( not $digits_used[$digit]) {
            $digits_used[$digit] = 1;
            if ($depth < 4) {
                find_digits($depth+1, ($total+$digit)*10);   #// recur
+se
            } else {
                print $total+$digit,"\n";
            }
            $digits_used[$digit] = 0;
        } #// if used
    } #// for digits
} #// end sub

__END__

c:\usr\scripts>sundial.pl | find /c /v ""
5040

I've always been fascinated with recursive code but there are times when it isn't a good fit for a problem. Those times are any time there is a simpler solution. To produce the 5040 permutations without repeats you only need to eliminate duplicate digits from 0..9999. This can be done with a simple regex and sprintf on a Perl one liner. This looks like a good start for a competition for code obfuscation. Where did you find this code?

[karlgoethebier]

"... pseudo code..."

Very optimistic. See also.

Best regards, Karl