day2

day2/day2.pl

@@ -0,0 +1,7 @@
+#!/usr/bin/perl
+
+use 5.20.0;
+
+use List::AllUtils qw/ minmax sum pairmap /;
+
+say sum pairmap { -$a, $b } map { minmax split } <>;

day2/day2b.pl

@@ -0,0 +1,14 @@
+#!/usr/bin/perl
+
+use 5.20.0;
+use experimental 'signatures';
+
+use List::AllUtils qw/ sum first /;
+
+say sum map { divisors( sort { $b <=> $a } split ) } <>;
+
+sub divisors(@nums) {
+    while( my $x = shift @nums ) {
+        return $x / $_ for grep { defined $_ } first { not $x % $_ } @nums;
+    }
+}