Merge pull request #8123 from steve-g-lynn/branch-for-challenge-218

pwc-218

3 files changed, 78 insertions, 0 deletions

diff --git a/challenge-218/steve-g-lynn/blog.txt b/challenge-218/steve-g-lynn/blog.txt
new file mode 100644
index 0000000000..40e5ecb8b9
--- /dev/null
+++ b/challenge-218/steve-g-lynn/blog.txt
@@ -0,0 +1 @@
+https://thiujiac.blogspot.com/2023/05/pwc-218.html
diff --git a/challenge-218/steve-g-lynn/perl/ch-1.pl b/challenge-218/steve-g-lynn/perl/ch-1.pl
new file mode 100755
index 0000000000..0951ddb2ca
--- /dev/null
+++ b/challenge-218/steve-g-lynn/perl/ch-1.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/env -S perl -wl
+
+use List::Util qw(max);
+
+local *maximum_product = sub {
+    
+    local *myprod=sub {
+        $_[0]*$_[1]*$_[2];
+    };
+
+    #-- main part of &maximum_product
+    my @list = sort {$a <=> $b} @_;
+    
+    (scalar(@list) < 2) && (die "Need at least 3 elements in input"); 
+
+    max( 
+        &myprod( $list[0], $list[1], $list[-1] ),
+        &myprod( $list[-1], $list[-2], $list[-3] )
+    );
+};
+
+print &maximum_product( 3, 1, 2); #6
+print &maximum_product( 4, 1, 3, 2); #24
+print &maximum_product( -1, 0, 1, 3, 1); #3
+print &maximum_product( -8, 2, -9, 0, -4, 3); #216
diff --git a/challenge-218/steve-g-lynn/perl/ch-2.pl b/challenge-218/steve-g-lynn/perl/ch-2.pl
new file mode 100755
index 0000000000..ef2cbd7162
--- /dev/null
+++ b/challenge-218/steve-g-lynn/perl/ch-2.pl
@@ -0,0 +1,52 @@
+#!/usr/bin/env -S perl -wl
+
+#-- algorithm from https://leetcode.com/problems/score-after-flipping-matrix/solutions/2563853/easy-to-understand-basic-python-solution-with-explanation/
+
+use PDL;
+use PDL::NiceSlice;
+use PDL::AutoLoader;
+
+sub matrix_score {
+
+    local *flip_col = sub {
+        my ($col)=@_;
+        $matrix($col) .= !$matrix($col);
+    };
+    
+    local *flip_row = sub {
+        my ($row)=@_;
+        $matrix(,$row) .= !$matrix(,$row);
+    };
+    
+    local *binary_row = sub {
+        my ($row)=@_;
+        oct '0b' . (join( '', $matrix(,$row)->list));
+    };
+
+    #-- main portion of sub
+    local ($matrix)=@_; #--pdl
+    #-- I leave out input validation chores
+    
+    my ($ncol, $nrow)=($matrix->dims);
+    
+    for my $ctr (0 .. $nrow-1) {
+    #-- check if row starts with 0, if so, flip
+        ($matrix(0,$ctr)==0) && (&flip_row($ctr));
+    }
+    
+    for my $ctr (0 .. $ncol-1) {
+    #-- check if number of 1's in column < 0.5 * nrow
+    #-- if so, flip column 
+    ( ($matrix($ctr)->sum) < ($nrow/2) ) && ( &flip_col($ctr) );
+    }
+    
+    #-- add up binary representations of each row    
+    my $retval=0b0;
+    for my $ctr (0 .. $nrow-1) {
+        $retval += &binary_row($ctr); 
+    }
+    sprintf("%d",$retval);
+}
+
+print &matrix_score(pdl '[0,0,1,1; 1,0,1,0; 1,1,0,0]'); #39
+print &matrix_score(pdl '[[0]]'); #1