sub fys {
    my $arr = shift;
    my $i = @{ $arr };
    while ( $i ) {
        my $j = int rand $i;
        @$arr[$i,$j] = @$arr[$j,$i];
        --$i;
    }
}

##</code><code>##

@nums = map [ @{$_}[@cols] ], @nums;

##</code><code>##

my @cols = 0..11;
do {
  fys( \@cols );
} until is_deranged( \@cols );

##</code><code>##

sub is_deranged {
  my $arr = shift;
  $arr->[ $_ ] == $_ and return for 0..$#$arr;
  return 1;
}

##</code><code>##

use strict;
use warnings;

my @cols = qw/0 1 2 3 4 5 6 7 8 9 10 11/;
fys( \@cols );

my @nums = ( [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
             [qw/01 02 03 04 05 06 07 08 09 10 11 12/],
           );
@nums = map [ @{$_}[@cols] ], @nums;
# for( my $i = 0; $i < 12; $i++) {
#     for( my $j = 0; $j < 6; $j++) {
#         ($nums[$i][ $cols[$j] ], $nums[$i][ $cols[$j+6] ]) = ($nums[$i][ $cols[$j+6] ], $nums[$i][ $cols[$j] ]);
#     }
# }

&printit;

sub printit() {
    for( my $i = 0; $i < 12; $i++) {
        print "@{ $nums[$i] } ";
        print "\n";
    }
}

sub fys {
    my $arr = shift;
    my $i;
    for( $i = @{ $arr }; $i--;) {
#        my $j = int rand ($i + 1);
        my $j = int rand $i;
        next if $i == $j;
        @$arr[$i,$j] = @$arr[$j,$i];
    }
}