aoc2021

commit 353e09d4a93cd8a84a3a363f058290f6a4a1dc0c
parent 44c1283941f94fc997dc5625192ae7a89456106f
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Mon, 27 Dec 2021 01:12:00 +0000

update day11-1.pl to provide working solution for Day 11 Part 1

Diffstat:
M
day11-1.pl
 | 
77
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-

1 file changed, 76 insertions(+), 1 deletion(-)
diff --git a/day11-1.pl b/day11-1.pl
@@ -3,10 +3,11 @@
 use strict;
 use warnings;
 use v5.22;
-use Math::BigInt;
 
 # Day 11, Part 1
 
+use constant FLASH_LIMIT => 9;
+
 sub get_filehandle {
   if (@ARGV !=1) {
     die "Usage: $0 [input-filename]";
@@ -17,6 +18,17 @@ sub get_filehandle {
   return $filehandle;
 }
 
+sub print_octopuses {
+    my ($oct_ref, $rows, $columns) = @_;
+    my @octopuses = @{$oct_ref};
+    foreach my $row (0 .. $rows - 2) {
+        foreach my $column (0 .. $columns - 2) {
+            print $octopuses[$row][$column];
+        }
+        print "\n";
+    }
+    print "\n";
+}
 
 my $filehandle  =  get_filehandle();
 # add extra column of negative infinity
@@ -25,3 +37,66 @@ my $columns     =  @{$octopuses[0]};
 # add extra row of negative infinity
 push @octopuses => [ ("-inf") x $columns ];
 my $rows        =  @octopuses;
+my @neighbors;
+foreach my $nr (-1 .. 1) {
+    foreach my $nc (-1 .. 1) {
+        push @neighbors => [$nr, $nc] unless ($nr == 0 && $nc == 0);
+    }
+}
+my $flash_count = 0;
+
+print_octopuses(\@octopuses, $rows, $columns);
+#say $rows, " x ", $columns;
+#say "@$_" foreach @neighbors;
+foreach my $step (1 .. 100) {
+    #say "after step $step";
+    my @queue = ();
+    my %flash_state = ();
+# 10 iterate through each octopus and increment its counter by 1
+    foreach my $row (0 .. $rows - 2) {
+        foreach my $column (0 .. $columns - 2) {
+            $octopuses[$row][$column]++;
+# 20 iterate through each octopus and see whether its energy level
+#    is greater than 9
+            if ($octopuses[$row][$column] > FLASH_LIMIT &&
+                !exists $flash_state{$row, $column}) {
+# 30 for any octupus whose energy level is greater than 9 AND which
+#    has not yet flashed in this step:
+#    - update its state in a hash indicating that it has flashed
+#    - increment the flash counter
+#    - add its position to a queue which we will iterate through to
+#      increase the energy level of adjacent octupuses
+                $flash_state{$row, $column} = 1;
+                $flash_count++;
+                push @queue => [ $row, $column ];
+            }
+        }
+    }
+    while (@queue) {
+        my $octopus = shift @queue;
+        my $r = $octopus->[0];
+        my $c = $octopus->[1];
+        foreach my $neighbor (@neighbors) {
+            my $neighbor_row = $r + $neighbor->[0];
+            my $neighbor_col = $c + $neighbor->[1];
+            $octopuses[$neighbor_row][$neighbor_col]++;
+            if ($octopuses[$neighbor_row][$neighbor_col] > FLASH_LIMIT &&
+                !exists $flash_state{$neighbor_row, $neighbor_col}) {
+                $flash_state{$neighbor_row, $neighbor_col} = 1;
+                $flash_count++;
+                push @queue => [ $neighbor_row, $neighbor_col ];
+            }
+        }
+    }
+    foreach my $row (0 .. $rows -2) {
+        foreach my $column (0 .. $columns - 2) {
+            if (exists $flash_state{$row, $column} &&
+                $flash_state{$row, $column} == 1) {
+                $octopuses[$row][$column] = 0;
+            }
+        }
+    }
+    #print_octopuses(\@octopuses, $rows, $columns);
+}
+
+say "part 1 flash counts = $flash_count";