2020/day16.pl


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use strict;
use warnings;

my (%rules, @ticket, @nearby);
while (<>) {
	chomp;
	if (/([^:]+): (\d+)-(\d+) or (\d+)-(\d+)/) {
		$rules{$1} = [$2, $3, $4, $5];
	} elsif (/your ticket:/) {
		<>;
		chomp;
		@ticket = split ',';
	} elsif (/^[\d,]+$/) {
		my @fields = split ',';
		push @nearby, \@fields;
	}
}

my $error = 0;
foreach my $t (@nearby) {
	foreach my $f (@$t) {
		my $valid = 0;
		foreach my $r (values %rules) {
			$valid = 1 if $f >= $$r[0] && $f <= $$r[1];
			$valid = 1 if $f >= $$r[2] && $f <= $$r[3];
		}
		$error += $f unless $valid;
	}
}
print "$error\n";