Re: something about improving code...

[reptile]

For your flip, you don't even need to use a reference. Modifying @_ in a subroutine also modifies the variables in the argument list. You could say this:

sub flip { $_[0] = !($_[0]) }
# $foo will be modified below
flip($foo);

I'm not positive about this but AFAIK since that's a one line subroutine, perl will optomize by inlining the subroutine, and be even faster. Still, $foo = !$foo; isn't that hard to write directly. Whatever you prefer.

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