Re: Unique Character Combinations

Your solution is perhaps more elegant, but it's also less efficient, as data has to be passed back between instances of the function. I tested, and on the call:

my @arr = comb('A'..'R');
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my code took approx. 23 seconds, while yours took 30.

Comment on Re: Unique Character Combinations Download Code

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Re^2: Unique Character Combinations by polettix (Vicar) on May 02, 2005 at 13:52 UTC
But you can work around this passing a reference to the final array: `use strict; use warnings; print join "\n", comb_thormod('A'..'R'); sub comb_thormod { my $c_out = []; permute_thormod( '', $_, $c_out, @_ ) for ( 0 .. $#_ ); return @$c_out; } sub permute_thormod { my ( $str, $depth, $c_out, @chars ) = @_; if ( !$depth-- ) { foreach (@chars) { push @$c_out, $str . $_; } } else { permute_thormod( $str . $chars[$_], $depth, $c_out, @chars[ ( $_ + 1 ) .. ($#chars) ] ) for ( 0 .. $#chars ); } }` [download] even if results show your solution is still slightly more efficient (-2% / 5% scissor). Read more... (3 kB) OTOH, I'd still prefer the version without the static variable - should work in a multithreaded environment, at least :) Flavio (perl -e 'print(scalar(reverse("\nti.xittelop\@oivalf")))') Don't fool yourself.	[reply] [d/l] [select]

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Re^2: Unique Character Combinations
by polettix (Vicar) on May 02, 2005 at 13:52 UTC

use strict;
use warnings;

print join "\n", comb_thormod('A'..'R');

sub comb_thormod {
    my $c_out = [];
    permute_thormod( '', $_, $c_out, @_ ) for ( 0 .. $#_ );
    return @$c_out;
}

sub permute_thormod {
    my ( $str, $depth, $c_out, @chars ) = @_;
    if ( !$depth-- ) {
        foreach (@chars) {
            push @$c_out, $str . $_;
        }
    }
    else {
       permute_thormod( $str . $chars[$_], $depth, $c_out,
                        @chars[ ( $_ + 1 ) .. ($#chars) ] )
         for ( 0 .. $#chars );
    }
}
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