#! perl -slw
use strict;

my @sorted = 'a'..'z';
our $COLS ||= 3;
my $offset = int @sorted / $COLS;

for my $s ( 0 .. $offset ) { 
	print join' ', grep defined, @sorted[ 
		map{ $s + ($offset * $_) + $_ } 0 .. $COLS - 1 
	];
}
__END__
P:\test>test -COLS=3
a j s
b k t
c l u
d m v
e n w
f o x
g p y
h q z
i r

P:\test>test -COLS=4
a h o v
b i p w
c j q x
d k r y
e l s z
f m t
g n u

P:\test>test -COLS=5
a g m s y
b h n t z
c i o u
d j p v
e k q w
f l r x