aoc2015

commit 477ebae20e16f9e83a0eb5bece67257c5e5aacf6
parent b7256a030153d7fed87f12a9fd861a1ec6dfeda9
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Thu, 10 Nov 2022 23:42:17 +0000

solve part 2 of day18

Diffstat:
M
day18/Day18.pm
 | 
13
+++++++++++--
M
day18/day18.pl
 | 
19
+++++++++++--------

2 files changed, 22 insertions(+), 10 deletions(-)
diff --git a/day18/Day18.pm b/day18/Day18.pm
@@ -66,6 +66,7 @@ sub update_light
 sub flash_lights
 {
     my $current_state = shift;
+    my $part          = shift;
     # need to declare a clean, new array, completely separate from $current_state
     # so as not to alter the current state when updating the new state
     my @next_state;
@@ -73,7 +74,15 @@ sub flash_lights
     my $columns = scalar @{ $current_state->[ 0 ] };
     foreach my $row ( 0 .. $rows - 2 ) {
         foreach my $col ( 0 .. $columns - 2 ) {
-            $next_state[ $row ][ $col ] = update_light( $row, $col, $current_state );
+            if ( ( $part == 2 ) &&
+                 ( $row == 0 && $col == 0 ||
+                   $row == 0 && $col == $columns - 2 ||
+                   $row == $rows - 2 && $col == 0 ||
+                   $row == $rows - 2 && $col == $columns - 2 ) ) {
+                $next_state[ $row ][ $col ] = '#';
+            } else {
+                $next_state[ $row ][ $col ] = update_light( $row, $col, $current_state );
+            }
         }
         push @{ $next_state[ $row ] } => '.'; # add trailing column back in
     }
@@ -82,7 +91,7 @@ sub flash_lights
     return \@next_state;
 }
 
-sub display_lights # for debuggin purposes only
+sub display_lights # for debugging purposes only
 {
     say "@{ $_ }" foreach ( @{ shift() } );
 }
diff --git a/day18/day18.pl b/day18/day18.pl
@@ -8,18 +8,21 @@ use lib '.';
 use Day18;
 use List::Util qw( max );
 
+$| = 1;
+
 @ARGV = "input" unless @ARGV;
 chomp( my $input = do { local $/; <> } );
 my $STEPS         = 100;
-my $state         = init_lights( $input );
-
-say "Initial state:";
-#display_lights( $state );
+my $state_1       = init_lights( $input );
+my $state_2       = init_lights( $input );
 
 foreach ( 1 .. $STEPS )
 {
-    $state = flash_lights( $state );
+    print ".";
+    $state_1 = flash_lights( $state_1, 1 );
+    $state_2 = flash_lights( $state_2, 2 );
 }
-
-say "part 1: ", count_lights( $state );
-say "part 2: ";
+print "\n";
+#display_lights($state_2);
+say "part 1: ", count_lights( $state_1 );
+say "part 2: ", count_lights( $state_2 );