Merge pull request #8088 from pjcs00/wk217

Revised task 2!

1 files changed, 36 insertions, 4 deletions

diff --git a/challenge-217/peter-campbell-smith/perl/ch-2.pl b/challenge-217/peter-campbell-smith/perl/ch-2.pl
index c9adadc632..f8fc81c3a2 100755
--- a/challenge-217/peter-campbell-smith/perl/ch-2.pl
+++ b/challenge-217/peter-campbell-smith/perl/ch-2.pl
@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 
 use v5.16;    # The Weekly Challenge - 2023-05-15
-use utf8;     # Week 216 task 1 - Max number
+use utf8;     # Week 217 task 2 - Max number
 use strict;   # Peter Campbell Smith
 use warnings; # Blog: http://ccgi.campbellsmiths.force9.co.uk/challenge
 
@@ -10,11 +10,43 @@ max_number(10, 3, 2);
 max_number(31, 2, 4, 10);
 max_number(5, 11, 4, 1, 2);
 max_number(1, 10);
+max_number(9900, 1, 99, 88);
+max_number(47, 53, 99, 82, 9, 21, 36, 76, 77);
 
 sub max_number {
 	
-	# concatenate the numbers in descending alphabetical sort order
-	say qq[\nInput:  ] . join(', ', @_);
-	say qq[Output: ] . join('', reverse sort @_);
+	my (%left, $max);
+	
+	# put the numbers in a hash (as keys)
+	$left{$_} = 1 for @_;
+
+	# show result
+	say qq[\nInput: (] . join(', ', @_) . ')';
+	say qq[Output: ] . add_a_number(0, '', \%left);
 }
 
+sub add_a_number {
+	
+	my ($max, $so_far, $so_far2, %left, %more, $this);
+	
+	# initialise
+	$max = $_[0];
+	$so_far = $_[1];
+	%left = %{$_[2]};
+	
+	# added all numbers
+	unless (%left) {
+		$max = $so_far if $so_far > $max;
+	
+	# add the next number
+	} else {	
+		for $this (keys %left) {
+			%more = %left;
+			delete $more{$this};			
+			$max = add_a_number($max, $so_far . $this, \%more);
+		}
+	}
+	
+	# return the best so far
+	return $max;
+}