I pinched the following from tye's Permuting with duplicates and no memory 
sub nextPermute(\@)
{
    my( $vals )= @_;
    my $last= $#{$vals};
    return ""   if  $last < 1;
    # Find last item not in reverse-sorted order:
    my $i= $last-1;
    $i--   while  0 <= $i  &&  $vals->[$i] ge $vals->[$i+1];
    # If complete reverse sort, we are done!
    return ""   if  -1 == $i;
    # Re-sort the reversely-sorted tail of the list:
    @{$vals}[$i+1..$last]= reverse @{$vals}[$i+1..$last]
      if  $vals->[$i+1] gt $vals->[$last];
    # Find next item that will make us "greater":
    my $j= $i+1;
    $j++  while  $vals->[$i] ge $vals->[$j];
    # Swap:
    @{$vals}[$i,$j]= @{$vals}[$j,$i];
    return 1;
}

@A= sort qw[a r t];
do {
    print @A, "\n";
} while( nextPermute(@A) );
__OUTPUT__
art
atr
rat
rta
tar
tra

[download]
The output does not contain words like "at" but this might not be a problem if you do the pattern matching accordingly.

pelagic

In reply to Re: Finding words within a character set by pelagic
in thread Finding words within a character set by ruhk

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