aoc2021

commit e87a5bf731234a77f15b6b0817e03df783487764
parent c51f8db43b2c6899560cdebdce4707c8db4321cd
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Thu,  9 Dec 2021 00:15:11 +0000

update day05-1.pl to provide a much better solution

Diffstat:
M
day05-1.pl
 | 
56
+++++++++++++++++++++-----------------------------------

1 file changed, 21 insertions(+), 35 deletions(-)
diff --git a/day05-1.pl b/day05-1.pl
@@ -6,6 +6,17 @@ use v5.22;
 use List::Util qw( max );
 use diagnostics;
 
+sub draw_matrix {
+    my ($matrix) = shift;
+    my $answer;
+    foreach my $y (@$matrix) {
+        foreach my $x (@$y) {
+            $answer++ if (defined( $x ) && ($x > 1));
+        }
+    }
+    return $answer;
+}
+
 if (@ARGV !=1) {
     die "Usage: $0 [input-filename]";
 }
@@ -17,46 +28,21 @@ open my $filehandle, '<', $input_filename or
 chomp( my @input = ( <$filehandle> ) );
 my $wait;
 my @matrix = ();
-my $rows = 0;
-my $columns = 0;
+my ($rows, $columns) = (0, 0);
 foreach (@input) {
     my ($x1, $y1, $x2, $y2) = ( /(\d+),(\d+) -> (\d+),(\d+)/ );
-    if (($x2 <= $x1) && ($y2 <= $y1)) {
-        ($x2, $x1) = ($x1, $x2);
-        ($y2, $y1) = ($y1, $y2);
-    }
-    if (($x2 <= $x1) && ($y2 >= $y1)) {
-        ($x2, $x1) = ($x1, $x2);
-        ($y2, $y1) = ($y1, $y2);
-    }
-    $columns = max( $columns, $x1, $x2);
-    $rows    = max( $rows, $y1, $y2);
-    if (($x2 >= $x1) && ($y2 >= $y1)) {
-        for (my $x = $x1; $x < $x2 + 1; $x++) {
-            for (my $y = $y1; $y < $y2 + 1; $y++) {
-                if (($x1 == $x2) || ($y1 == $y2)) {
-                    $matrix[$y][$x]++;
-                }
-            }
+    if ($x1 == $x2) { # line is vertical
+        ($y1, $y2) = ($y2, $y1) if ($y1 > $y2); # swap so that $y1 < $y2
+        for (my $y = $y1; $y <= $y2; $y++) {
+            $matrix[$y][$x1]++;
         }
     }
-    elsif (($x2 >= $x1) && ($y2 <= $y1)) {
-        for (my $x = $x1; $x < $x2 + 1; $x++) {
-            for (my $y = $y2; $y < $y1 + 1; $y++) {
-                if (($x1 == $x2) || ($y1 == $y2)) {
-                    $matrix[$y][$x]++;
-                }
-            }
+    elsif ($y1 == $y2) { # line is horizontal
+        ($x1, $x2) = ($x2, $x1) if ($x1 > $x2); # swap so that $x1 < $x2
+        for (my $x = $x1; $x <= $x2; $x++) {
+            $matrix[$y1][$x]++;
         }
     }
 }
 
-my $answer;
-foreach my $y (0 .. $rows) {
-    foreach my $x (0 .. $columns) {
-        if (defined( $matrix[$y][$x] )) {
-            $answer++ if ($matrix[$y][$x] > 1);
-        }
-    }
-}
-say "answer is $answer";
+say draw_matrix( \@matrix );