use feature qw(say);

my @widths = (2, 6, 5, 7);
foreach (1 .. 2) {
	my @partitions = do { my $c = 0; map { $c += $_; [$c - $_, $c] } @widths};

	say '[', join(', ', @$_), ']' for @partitions;
	print "\n";
}