commit f225e16c8183a8414a349b0ea5a7644110155f80
parent 8e66f05b398baf40c15fa401b840a2f8b9874753
Author: Samir Parikh <noreply@samirparikh.com>
Date: Tue, 21 Dec 2021 17:08:53 +0000
combine programs for parts 1 and 2 into one program (day09.pl)
Diffstat:
| D | day09-1.pl | | | 29 | ----------------------------- |
| D | day09-2.pl | | | 77 | ----------------------------------------------------------------------------- |
| A | day09.pl | | | 74 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
3 files changed, 74 insertions(+), 106 deletions(-)
diff --git a/day09-1.pl b/day09-1.pl
@@ -1,29 +0,0 @@
-#!/usr/bin/env perl
-
-use strict;
-use warnings;
-use v5.22;
-use Data::Dumper;
-
-my @heightmap = map{ [m/\d/g, 10] } <>; # add extra column of 10s
-my $columns = @{$heightmap[0]};
-push @heightmap => [ (10) x $columns ]; # add extra row of 10s
-my $rows = @heightmap;
-my $risk_level = 0;
-
-foreach my $row (0 .. $rows - 2) { # don't care about last row that we added
- foreach my $column (0 .. $columns - 2) { # don't care about the last column
- my $height = $heightmap[$row][$column];
- my $lowpoint = 1; # true
- foreach my $offset ([0, -1], [0, 1], [-1, 0], [1, 0]) {
- if ($height >=
- $heightmap[$row + $offset->[0]][$column + $offset->[1]]) {
- $lowpoint = 0; # set to false
- last;
- }
- }
- $risk_level += $height + 1 if $lowpoint;
- }
-}
-
-say $risk_level;
diff --git a/day09-2.pl b/day09-2.pl
@@ -1,77 +0,0 @@
-#!/usr/bin/env perl
-
-use strict;
-use warnings;
-use v5.22;
-use Data::Dumper;
-
-sub find_basin {
- my ($row, $column, $heightmap_ref) = @_;
- my $size = 1; # lowpoint is already part of basin
- my @queue = ( [$row, $column] );
- while ( @queue ) { # there are still locations in queue to check
- my $location = shift @queue;
- my $r = $location->[0];
- my $c = $location->[1];
- my $location_height = $heightmap_ref->[$r][$c]; # can delete later
- say "checking location of $r, $c with height of $location_height";
- # don't want to double-count the initial lowpoint
- $heightmap_ref->[$r][$c] = 9;
- # check surrounding locations for increase in height
- foreach my $offset ([0, -1], [0, 1], [-1, 0], [1, 0]) {
- my $neighbor_row = $r + $offset->[0];
- my $neighbor_col = $c + $offset->[1];
- my $neighbor_height = $heightmap_ref->[$neighbor_row][$neighbor_col];
- say "neighbor at $neighbor_row, $neighbor_col has height $neighbor_height";
- next if ($neighbor_height == 9);
- #if ($neighbor_height == $location_height + 1) { # found increase
- say "found winner";
- # add neighbor coordinates to queue and set its height to 9 to prevent
- # it from being checked again (double-counted)
- push @queue => [ $neighbor_row, $neighbor_col ]; # add neighbor to queue
- $heightmap_ref->[$neighbor_row][$neighbor_col] = 9;
- $size++;
- #}
- }
- }
- #say "row is $location->[0] and column is $location->[1]";
- #my $location_height = $heightmap_ref->[$location->[0]][$location->[1]];
- #say "recvd lowpoint of height $location_height at $row, $column";
- return $size;
-}
-
-my @heightmap = map{ [m/\d/g, 9] } <>; # add extra column of 9s
-my $columns = @{$heightmap[0]};
-push @heightmap => [ (9) x $columns ]; # add extra row of 9s
-my $rows = @heightmap;
-my $risk_level = 0;
-my @basin_sizes;
-
-foreach my $row (0 .. $rows - 2) { # don't care about last row that we added
- foreach my $column (0 .. $columns - 2) { # don't care about the last column
- my $height = $heightmap[$row][$column];
- my $lowpoint = 1; # true
- foreach my $offset ([0, -1], [0, 1], [-1, 0], [1, 0]) {
- if ($height >=
- $heightmap[$row + $offset->[0]][$column + $offset->[1]]) {
- $lowpoint = 0; # set to false
- last;
- }
- }
- # found low point
- if ($lowpoint) {
- say "======================================";
- say "found lowpoint at $row, $column with height of $height";
- $risk_level += $height + 1;
- my $basin_size = find_basin( $row, $column, \@heightmap );
- say "basin size is $basin_size";
- push @basin_sizes => $basin_size;
- }
- }
-}
-
-say $risk_level;
-# plain `sort` routine just sorts by strings in code point order
-@basin_sizes = sort { $a <=> $b} @basin_sizes;
-say "@basin_sizes";
-say $basin_sizes[-3] * $basin_sizes[-2] * $basin_sizes[-1];
diff --git a/day09.pl b/day09.pl
@@ -0,0 +1,74 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use v5.22;
+
+sub get_filehandle {
+ if (@ARGV !=1) {
+ die "Usage: $0 [input-filename]";
+ }
+ my $input_filename = $ARGV[0];
+ open my $filehandle, '<', $input_filename or
+ die "Could not open input file $input_filename: $!";
+ return $filehandle;
+}
+
+sub find_basin {
+ my ($row, $column, $heightmap_ref) = @_;
+ my $size = 1; # lowpoint is already part of basin
+ my @queue = ( [$row, $column] );
+ while ( @queue ) { # there are still locations in queue to check
+ my $location = shift @queue;
+ my $r = $location->[0];
+ my $c = $location->[1];
+ # don't want to double-count the initial lowpoint
+ $heightmap_ref->[$r][$c] = 9;
+ # check surrounding locations for increase in height
+ foreach my $offset ([0, -1], [0, 1], [-1, 0], [1, 0]) {
+ my $neighbor_row = $r + $offset->[0];
+ my $neighbor_col = $c + $offset->[1];
+ my $neighbor_height = $heightmap_ref->[$neighbor_row][$neighbor_col];
+ next if ($neighbor_height == 9);
+ # add neighbor coordinates to queue and set its height to 9 to prevent
+ # it from being checked again (double-counted)
+ push @queue => [ $neighbor_row, $neighbor_col ];
+ $heightmap_ref->[$neighbor_row][$neighbor_col] = 9;
+ $size++;
+ }
+ }
+ return $size;
+}
+
+my $filehandle = get_filehandle();
+my @heightmap = map{ [m/\d/g, 9] } <$filehandle>; # add extra column of 9s
+my $columns = @{$heightmap[0]};
+push @heightmap => [ (9) x $columns ]; # add extra row of 9s
+my $rows = @heightmap;
+my $risk_level = 0;
+my @basin_sizes;
+
+foreach my $row (0 .. $rows - 2) { # don't care about last row that we added
+ foreach my $column (0 .. $columns - 2) { # don't care about the last column
+ my $height = $heightmap[$row][$column];
+ my $lowpoint = 1; # true
+ foreach my $offset ([0, -1], [0, 1], [-1, 0], [1, 0]) {
+ if ($height >=
+ $heightmap[$row + $offset->[0]][$column + $offset->[1]]) {
+ $lowpoint = 0; # set to false
+ last;
+ }
+ }
+ # found low point
+ if ($lowpoint) {
+ $risk_level += $height + 1;
+ my $basin_size = find_basin( $row, $column, \@heightmap );
+ push @basin_sizes => $basin_size;
+ }
+ }
+}
+
+say $risk_level;
+# plain `sort` routine just sorts by strings in code point order
+@basin_sizes = sort { $a <=> $b} @basin_sizes;
+say $basin_sizes[-3] * $basin_sizes[-2] * $basin_sizes[-1];
