Robbie Hatley's Perl solutions to The Weekly Challenge 211

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diff --git a/challenge-211/robbie-hatley/blog.txt b/challenge-211/robbie-hatley/blog.txt
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+https://hatley-software.blogspot.com/2023/04/robbie-hatleys-perl-solutions-to-weekly.html
\ No newline at end of file
diff --git a/challenge-211/robbie-hatley/ch-1.pl b/challenge-211/robbie-hatley/ch-1.pl
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+#! /bin/perl
+# Robbie Hatley's Perl solutions to The Weekly Challenge #211-1
+
+# ======================================================================
+# PROBLEM DESCRIPTION:
+
+=pod
+
+Task 1: Toeplitz Matrix
+Submitted by: Mohammad S Anwar
+You are given a matrix m x n. Write a script to find out if the given 
+matrix is Toeplitz Matrix. A matrix is Toeplitz if every diagonal from 
+top-left to bottom-right has the same elements.
+
+Example 1:
+Input:  [[4, 3, 2, 1], [5, 4, 3, 2], [6, 5, 4, 3]]
+Output: true
+
+Example 2:
+Input:  [[1, 2, 3], [3, 2, 1]]
+Output: false
+
+=cut
+
+# ======================================================================
+# INPUT / OUTPUT NOTES:
+# Input is from built-in array-of-arrays or from @ARGV. If using @ARGV,
+# input should be one 'single-quoted' string expressing an array of 
+# arrays of arrays of integers in valid Perl syntax, with each array
+# containing only arrays of the same size, like so:
+# ./ch-1.pl '([[1,2],[2,3]], [[1,3,5],[3,5,1],[5,1,3]])'
+#
+# Output is to STDOUT and will be the input array followed by
+# "Matrix IS Toeplitz" or "Matrix is NOT Toeplitz"
+
+# ======================================================================
+# PRELIMINARIES:
+use v5.36;
+use strict;
+use warnings;
+
+# ======================================================================
+# SUBROUTINES:
+
+# Say whether-or-not a referred-to rectangular 2-d matrix is Toeplitz,
+# without altering the original matrix:
+sub is_toeplitz($mref){
+   # Make a deep copy of @$aref (simple copy is NOT deep copy!!!):
+   my $height = scalar(@$mref);
+   my $width  = scalar(@{$mref->[0]});
+   say "Height = $height";
+   say "Width  = $width";
+   # Test length 2+ diagonals starting from top:
+   for ( my $i = 0 ; $i <= $width-2 ; ++$i ){
+      for ( my $j = $i+1, my $k = 1 ; $j < $width && $k < $height ; ++$j, ++$k ){
+         return 0 if $mref->[$k]->[$j] != $mref->[0]->[$i];
+      }
+   }
+   # Test length 2+ diagonals starting from left:
+   for ( my $i = 1 ; $i <= $height-2 ; ++$i ){
+      for ( my $j = 1, my $k = $i+1 ; $j < $width && $k < $height ; ++$j, ++$k ){
+         return 0 if $mref->[$k]->[$j] != $mref->[$i]->[0];
+      }
+   }
+   return 1;
+}
+
+# ======================================================================
+# DEFAULT INPUTS:
+my @matrices = 
+(
+   [[4, 3, 2, 1], [5, 4, 3, 2], [6, 5, 4, 3]],
+   [[1, 2, 3], [3, 2, 1]],
+   [[1,2],[2,1]],
+   [[1,3,5],[3,5,1],[5,1,3]],
+   [[1,5],[4,1],[2,4]],
+);
+
+# ======================================================================
+# NON-DEFAULT INPUTS:
+if (@ARGV) {@matrices = eval($ARGV[0])}
+
+# ======================================================================
+# MAIN BODY OF SCRIPT:
+for my $matrix (@matrices){
+   say '';
+   say 'Matrix:';
+   say "@$_" for @$matrix;
+   say is_toeplitz($matrix) ? "Matrix IS Toeplitz" : "Matrix is NOT Toeplitz";
+}
diff --git a/challenge-211/robbie-hatley/ch-2.pl b/challenge-211/robbie-hatley/ch-2.pl
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+#! /bin/perl
+# Robbie Hatley's Perl solutions to The Weekly Challenge #211-2
+
+# ======================================================================
+# PROBLEM DESCRIPTION:
+
+=pod
+
+Task 2: Split Same Average
+Submitted by: Mohammad S Anwar
+You are given an array of integers. Write a script to find out if the 
+given can be split into two separate arrays whose average are the same.
+
+Example 1:  Input=(1, 2, 3, 4, 5, 6, 7, 8)  Output=true
+Example 2:  Input=(1, 3)                    Output=false
+
+=cut
+
+# ======================================================================
+# INPUT / OUTPUT NOTES:
+# Input is from built-in array-of-arrays or from @ARGV. If using @ARGV,
+# input should be one 'single-quoted' string expressing an array of 
+# arrays of integers in valid Perl syntax.
+#
+# Output is to STDOUT and will be input array followed by either 
+# a split with equal averages or a notice that no such split exists.
+
+# ======================================================================
+# PRELIMINARIES:
+use v5.36;
+use strict;
+use warnings;
+use Set::Partition;
+use List::AllUtils 'sum0';
+$"=', ';
+
+# ======================================================================
+# VARIABLES:
+my $db = 0; # Debug?
+
+# ======================================================================
+# SUBROUTINES:
+
+# Obtain an array of all partitions of a given set into two non-empty
+# parts with the size of the first part not-greater-than the size of the
+# second part (to avoid duplicate partitions):
+sub two_non_empty ($aref, $partref){
+   # How big is the original array?
+   my $size  = scalar(@{$aref});
+   # No need to allow the first part to be more than half the size
+   # of the array, else we'd get duplicate partitions:
+   my $limit = int($size/2);
+   for ( my $n = 1 ; $n <= $limit ; ++$n ){
+      my $parts = Set::Partition->new(
+         list      => $aref,
+         partition => [$n, $size - $n],
+      );
+      while (my $part = $parts->next) {
+         push @{$partref}, $part;
+      }
+   }
+}
+
+# What is the average of the real numbers in a referred-to array?
+sub average ($aref) {return sum0(@$aref)/scalar(@$aref);}
+
+# Are two floating-point numbers "equal" to within one millionth?
+sub equal ($x, $y) {abs($x-$y) < 0.000001 ? return 1 : return 0;}
+
+# ======================================================================
+# DEFAULT INPUTS:
+my @arrays = 
+(
+   [1, 2, 3, 4, 5, 6, 7, 8],
+   [1, 3],
+   [3, 6, -2.3, 8.64, 5.36],
+   [3, 6, -2, 8, 5],
+   [4, 6, 8, 9]
+);
+
+# ======================================================================
+# NON-DEFAULT INPUTS:
+if (@ARGV) {@arrays = eval($ARGV[0])}
+
+# ======================================================================
+# MAIN BODY OF SCRIPT:
+
+ARRAY: for (@arrays){
+   say '';
+   say "array = (@$_)";
+   my $partitions = [];
+   two_non_empty($_, $partitions);
+   my $equal_average_flag = 0;
+   # If debugging, print lots of extra diagnostics:
+   if ($db) {
+      say 'Partitions:';
+      for (@$partitions){
+         my $a1 = average($_->[0]);
+         my $a2 = average($_->[1]);
+         my $e = equal($a1, $a2) ? 'EQUAL!!!' : '';
+         say("(@{$_->[0]}) (@{$_->[1]}) $a1 $a2 $e");
+      }
+   }
+   # Otherwise, just print the basics:
+   else {
+      for (@$partitions){
+         my $a1 = average($_->[0]);
+         my $a2 = average($_->[1]);
+         if (equal($a1, $a2)) {
+            say 'array can be split into '
+              . "(@{$_->[0]}) and (@{$_->[1]}), "
+              . "both with average $a1";
+            next ARRAY;
+         }
+      }
+      say 'No equal-average split exists.';
+   }
+}