this algorithm for shuffling arrays is called Fisher-Yates shuffling, i shamelessly pasted it from the Perl Cookbook :)

sub shuffle {
    my $arr = shift;
    my $x;
    for ($x = @$arr; --$x; ) {
        my $y = int rand ($x+1);
        next if $x == $y;
        @$arr[$x,$y] = @$arr[$y,$x];
    }
}

shuffle(\@array);
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