add challenge 087 solutions

3 files changed, 153 insertions, 0 deletions

diff --git a/challenge-087/samir-parikh/perl/blog.txt b/challenge-087/samir-parikh/perl/blog.txt
new file mode 100644
index 0000000000..4bd5db1661
--- /dev/null
+++ b/challenge-087/samir-parikh/perl/blog.txt
@@ -0,0 +1 @@
+https://samirparikh.com/blog/perl-weekly-challenge-087.html
diff --git a/challenge-087/samir-parikh/perl/ch-1.pl b/challenge-087/samir-parikh/perl/ch-1.pl
new file mode 100755
index 0000000000..28e9c21cc0
--- /dev/null
+++ b/challenge-087/samir-parikh/perl/ch-1.pl
@@ -0,0 +1,34 @@
+#!/usr/local/bin/perl
+
+use warnings;
+use strict;
+use feature 'say';
+
+# run program as:
+# $ ./ch-1.pl "100, 4, 50, 3, 2"
+my @input = split /, /, $ARGV[0];
+my $longestSequenceLength = 0;
+my @longestSequence;
+
+foreach my $i (@input) {
+    my @currentSequence;
+    push (@currentSequence, $i);
+    my $currentSequenceLength = 1;
+    my $checkFor = $i + 1;
+    while ( grep( $_ eq $checkFor, @input ) ) {
+        $currentSequenceLength++;
+        push (@currentSequence, $checkFor);
+        $checkFor++;
+    }
+    if ($currentSequenceLength > $longestSequenceLength) {
+        $longestSequenceLength = $currentSequenceLength;
+        @longestSequence = @currentSequence;
+    }
+}
+
+print "Output: ";
+if ($longestSequenceLength > 1) {
+    say "(", join(", ", @longestSequence), ")";
+} else {
+    say 0;
+}
diff --git a/challenge-087/samir-parikh/perl/ch-2.pl b/challenge-087/samir-parikh/perl/ch-2.pl
new file mode 100755
index 0000000000..5e6b3b0aa1
--- /dev/null
+++ b/challenge-087/samir-parikh/perl/ch-2.pl
@@ -0,0 +1,118 @@
+#!/usr/local/bin/perl
+
+use v5.10;
+use warnings;
+use strict;
+
+sub define_matrix {
+    open (INPUT, '<', $_[0]) or die "$!: could not open file $_[0]";
+    say "Input:";
+    my (@line, @matrix, $rows, $columns);
+    while (<INPUT>) {
+        chomp;
+        say $_;
+        s/\[ //;
+        s/ \]//;
+        @line = split / /, $_;
+# see https://stackoverflow.com/a/22291537
+        push (@matrix, [@line]);
+    }
+    close (INPUT) or die "$!: could not close file $_[0]";
+    $rows    = scalar @matrix;
+    $columns = scalar @line;
+# see http://perlmeme.org/faqs/perl_thinking/returning.html
+# I need to return the scalar variables before the array so that
+# they are assigned properly in the main program.  Otherwise,
+# the array will "capture" the scalar variables and the scalar
+# variables will be undefined.
+    return ($rows, $columns, @matrix);
+}
+
+sub all_ones {
+# see https://stackoverflow.com/a/2305559
+    if (@_ == grep { $_ eq '1' } @_) {
+        return 1;
+    } else {
+        return 0;
+    }
+# assuming that the values of all array elements are either 0 or 1,
+# you could also check whether the sum of the elements of the array
+# equals the length.  I feel that the method I went with is more
+# idomatic, or at least I think it is.
+}
+
+sub print_solution {
+    my ($rows, $columns, $topleft_column, $topleft_row,
+        $bottomright_column, $bottomright_row) = @_;
+    for (my $row = 0; $row < $rows; $row++) {
+        print "[ ";
+        for (my $column = 0; $column < $columns; $column++) {
+            if ($row < $topleft_row || $row > $bottomright_row) {
+                print "_ ";
+            } elsif ($column < $topleft_column || $column > $bottomright_column) {
+                print "_ ";
+            } else {
+                print "1 ";
+            }
+        }
+        print "]\n";
+    }
+}
+
+# the variables are specifically declared in this order so that
+# the scalar variables ($rows, $columns) are defined properly.
+# If I put the arracy (@matrix) first, it also "captures" the
+# scalar variables leaving $rows and $columns undefined.
+# see https://stackoverflow.com/q/55299734 for more information.
+my ($num_rows, $num_columns, @matrix) = &define_matrix($ARGV[0]);
+my $largest_rectangle_area = 0;
+my @largest_rectangle_vertices;
+# @largest_rectangle_vertices(topleft_column, topleft_row,
+#                             bottomright_column, bottomright_row)
+
+# traverse the matrix
+# find top right corner
+# start at the top and work your way down
+for (my $r = 0; $r < ($num_rows - 1); $r++) {
+# start at the left and work your way to the right
+    for (my $c = 0; $c < ($num_columns - 1); $c++) {
+# find bottom left corner
+# start at the far right and work your way left
+        for (my $right_column = $num_columns - 1;
+             $right_column > $c;
+             $right_column--) {
+# start at the top and work your way up
+            for (my $bottom_row = $num_rows - 1;
+                 $bottom_row > $r;
+                 $bottom_row--) {
+                my $area = ($right_column - $c + 1) *
+                           ($bottom_row - $r + 1);
+# the next statement doesn't really save that much time but
+# no need to check a rectangle whose area is less than one
+# that has already been found
+                last if ($area < $largest_rectangle_area);
+                my @elements;
+# slurp all ones and zeros from the rectangle we defined
+                for (my $y = $r; $y <= $bottom_row; $y++) {
+                    my $rowref = $matrix[$y];
+                    push (@elements, @$rowref[$c .. $right_column]);
+                }
+                if (&all_ones(@elements)) {
+                    if ($area > $largest_rectangle_area) {
+                        $largest_rectangle_area = $area;
+                        @largest_rectangle_vertices = (
+                            $c, $r, $right_column, $bottom_row);
+                    }   # end if $area
+                }       # end if &all_ones
+            }           # end for $bottom_row
+        }               # end for $right_column
+    }                   # end for $c
+}                       # end for $r
+
+print "\n";
+if ($largest_rectangle_area) {
+    say "Largest rectangle found here:";
+    &print_solution($num_rows, $num_columns, @largest_rectangle_vertices);
+} else {
+    say "No rectangle found.";
+}