Merge pull request #4819 from simongreen-net/swg-128

sgreen solution to challenge 128

6 files changed, 131 insertions, 2 deletions

diff --git a/challenge-128/sgreen/README.md b/challenge-128/sgreen/README.md
index a8fab60739..93e51b94d6 100644
--- a/challenge-128/sgreen/README.md
+++ b/challenge-128/sgreen/README.md
@@ -1,3 +1,3 @@
-# The Weekly Challenge 127
+# The Weekly Challenge 128
 
-Solution by Simon Green. [Blog](https://dev.to/simongreennet/weekly-challenge-127-4k6j)
+Solution by Simon Green. [Blog](https://dev.to/simongreennet/weekly-challenge-128-1ng1)
diff --git a/challenge-128/sgreen/blog.txt b/challenge-128/sgreen/blog.txt
new file mode 100644
index 0000000000..af278f0388
--- /dev/null
+++ b/challenge-128/sgreen/blog.txt
@@ -0,0 +1 @@
+https://dev.to/simongreennet/weekly-challenge-128-1ng1
diff --git a/challenge-128/sgreen/perl/ch-1.pl b/challenge-128/sgreen/perl/ch-1.pl
new file mode 100755
index 0000000000..29a74f521e
--- /dev/null
+++ b/challenge-128/sgreen/perl/ch-1.pl
@@ -0,0 +1,71 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature 'say';
+
+sub _process_input {
+    my @rows  = @_;
+    my @cells = ();
+
+    # Convert rows of x and * to an array of arrays
+    foreach my $row (<>) {
+
+        # Skip empty rows
+        next if $row =~ /^\s+$/;
+        push @cells, [ $row =~ /([01])/gm ];
+    }
+
+    # Check we have at least one row
+    die "You must specify at least one row\n" unless scalar(@cells);
+
+    # Check all rows are the same length
+    foreach my $i ( 1 .. $#cells ) {
+        die "Not all rows are the same length\n" if scalar( @{ $cells[0] } ) != scalar( @{ $cells[$i] } );
+    }
+
+    return @cells;
+}
+
+sub main {
+    # Unlike most tasks, we will read the input from STDIN.
+    my @cells = _process_input();
+
+    my $rows       = $#cells;
+    my $cols       = $#{ $cells[0] };
+    my $best_width = my $best_height = 0;
+
+    # Inspect each cell as the top left of the inner matrix
+    foreach my $y ( 0 .. $rows ) {
+        foreach my $x ( 0 .. $cols ) {
+            # Skip cells that have a one
+            next if $cells[$y][$x] == 1;
+
+            my $max_width = $cols - $x;
+
+            foreach my $height ( 0 .. $rows - $y ) {
+                last if $cells[ $y + $height ][$x] == 1;
+
+                my $width = 0;
+                foreach my $this_width ( 1 .. $max_width ) {
+                    last if $cells[ $y + $height ][ $x + $this_width ] == '1';
+                    $max_width = $this_width;
+                    ++$width;
+                }
+
+                # This is matrix bigger than what we've already found
+                if ( ( $best_width * $best_height ) < ( ( $width + 1 ) * ( $height + 1 ) ) ) {
+                    $best_width  = $width + 1;
+                    $best_height = $height + 1;
+                }
+            }
+        }
+    }
+
+    # Display the result
+    my $row = '[ ' . ( '0 ' x $best_width ) . ']';
+    say $row foreach ( 1 .. $best_height );
+
+}
+
+main();
diff --git a/challenge-128/sgreen/perl/ch-2.pl b/challenge-128/sgreen/perl/ch-2.pl
new file mode 100755
index 0000000000..461410b728
--- /dev/null
+++ b/challenge-128/sgreen/perl/ch-2.pl
@@ -0,0 +1,51 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+use feature 'say';
+use List::Util 'max';
+
+sub _make_time {
+    # Turn a HH:MM time into minutes since midnight
+    my ( $hour, $min ) = split /:/, $_[0], 2;
+    return $hour * 60 + $min;
+}
+
+sub main {
+    # Get the times from the input
+    my @times = ( join( ' ', @_ ) =~ /((?:2[0-3]|[01][0-9]):[0-5][0-9])/g );
+
+    # Sanity check
+    die "You must provide an even amount of times" if $#times % 2 == 0;
+
+    # Pair up the arrival and departure times
+    my $offset = scalar(@times) / 2;
+    my @trains = ();
+    for my $pairs ( 0 .. $#times / 2 ) {
+        my $arr = _make_time( $times[$pairs] );
+        my $dep = _make_time( $times[ $pairs + $offset ] );
+
+        if ( $dep < $arr ) {
+            # The train spans across midnight, so add two entries
+            # There are 1440 minutes in a day, so 1439 is 11:59pm
+            push @trains, [ 0, $arr ], [ $dep, 1439 ];
+        }
+        else {
+            push @trains, [ $arr, $dep ];
+        }
+    }
+
+    # For each minute, figure out how many platforms are used
+    my @platforms = ( (0) x 1440 );
+    foreach my $train (@trains) {
+        foreach my $time ( $train->[0] .. $train->[1] ) {
+            $platforms[$time]++;
+        }
+    }
+
+    # Display the maximum number of platforms required
+    my $max_platforms = max(@platforms);
+    say $max_platforms;
+}
+
+main(@ARGV);
diff --git a/challenge-128/sgreen/perl/example1.txt b/challenge-128/sgreen/perl/example1.txt
new file mode 100644
index 0000000000..109dd5b3d6
--- /dev/null
+++ b/challenge-128/sgreen/perl/example1.txt
@@ -0,0 +1,3 @@
+[ 1 0 0 0 1 0 ]
+[ 1 1 0 0 0 1 ]
+[ 1 0 0 0 0 0 ]
diff --git a/challenge-128/sgreen/perl/example2.txt b/challenge-128/sgreen/perl/example2.txt
new file mode 100644
index 0000000000..3ee68404d8
--- /dev/null
+++ b/challenge-128/sgreen/perl/example2.txt
@@ -0,0 +1,3 @@
+[ 0 0 1 1 ]
+[ 0 0 0 1 ]
+[ 0 0 1 0 ]