day 5

2018/05/sol1.pl

@@ -0,0 +1,30 @@
+use 5.20.0;
+use warnings;
+
+use List::AllUtils qw/ uniq /;
+
+use experimental qw/
+    signatures
+    postderef
+/;
+
+my $code = <>;
+chomp $code;
+
+use DDP;
+
+say length react($code);
+
+
+sub react ($code) {
+    my @combos = map { create_dual($_) } uniq split '', $code;
+    my $re = join '|', @combos;
+
+    1 while $code =~ s/$re//g;
+
+    return $code;
+}
+
+sub create_dual($x) {
+    $x . ( $x eq uc $x ? lc $x : uc $x );
+}

2018/05/sol2.pl

@@ -0,0 +1,33 @@
+use 5.20.0;
+use warnings;
+
+use List::AllUtils qw/ uniq min /;
+
+use experimental qw/
+    signatures
+    postderef
+/;
+
+my $code = <>;
+chomp $code;
+
+use DDP;
+
+say min
+    map { length react($_) }
+    map { $code =~ s/$_//irg }
+    'a'..'z';
+
+
+sub react ($code) {
+    my @combos = map { create_dual($_) } uniq split '', $code;
+    my $re = join '|', @combos;
+
+    1 while $code =~ s/$re//g;
+
+    return $code;
+}
+
+sub create_dual($x) {
+    $x . ( $x eq uc $x ? lc $x : uc $x );
+}