1 files changed, 32 insertions, 0 deletions

diff --git a/2020/day6/group_declaration.pl b/2020/day6/group_declaration.pl
new file mode 100644
index 0000000..6370e2f
--- /dev/null
+++ b/2020/day6/group_declaration.pl
@@ -0,0 +1,32 @@
+use strict;
+use warnings;
+use Smart::Comments;
+use DDP;
+
+my $batch;
+{
+    local $/;
+    open my $fh, '<', "input" or die "no input present, $!";
+    $batch = <$fh>;
+}
+
+my $all_yeses = 0;
+
+while ($batch =~ m/((?:[^\n][\n]?)+)/gm ) {
+    my $group_answers = $1;
+
+    # count the newlines = number of people
+    my $peeps = $1 =~ tr/\n//;
+
+    chomp $group_answers;
+
+    my %counts;
+    while ($group_answers =~ m/^(\w+)$/mg) {
+        my $person_answers = $1;
+        ++$counts{$_} for split(//, $person_answers);
+    }
+
+    $all_yeses += scalar grep { $_ == $peeps } values %counts;
+}
+
+print $all_yeses;