2021/day01.pl


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use strict;
use warnings;
my ($last, @window, $incs, $incs2);
while (<>) {
	$incs++ if ($last && $_ > $last);
	$last = $_;
	if (scalar @window == 3) {
		my $prev = $window[0] + $window[1] + $window[2];
		my $next = $window[1] + $window[2] + $_;
		$incs2++ if ($next > $prev);
		shift @window;
	}
	push @window, $_;
}
print "$incs\n$incs2\n";