added my solutions to challenge 19

3 files changed, 98 insertions, 27 deletions

diff --git a/challenge-019/duncan-c-white/README b/challenge-019/duncan-c-white/README
index 0220538063..d120449c9b 100644
--- a/challenge-019/duncan-c-white/README
+++ b/challenge-019/duncan-c-white/README
@@ -1,33 +1,14 @@
-Challenge 1: "Write a script that takes 2 or more strings as command
-line parameters and print the longest common substring. For example,
-the longest common substring of the strings "ABABC", "ABCA" 
-and "BCBA" is string "BC" of length 3.
-"
+Challenge 1: "Write a script to display months from the year 1900 to 2019 where you find 5 weekends i.e. 5 Friday, 5 Saturday and 5 Sunday."
 
 My notes:
 
-Very clearly described.  No obvious clever way of solving this, but the
-basic method is simple.
+Clearly defined, although Friday isn't normally considered part of the weekend
+is it?  Anyway, it's clear here that Friday - Sunday is the weekend for the
+purposes of this question.  Date::Manip can do this easily enough.
 
 
-Challenge 2: "Write a script to implement Priority Queue. It is like
-regular queue except each element has a priority associated with it. In a
-priority queue, an element with high priority is served before an element
-with low priority. It should serve the following operations:
+Challenge 2: "Write a script that can wrap the given paragraph at a specified
+column using the greedy algorithm."
 
-1) is_empty: check whether the queue has no elements.
-
-2) insert_with_priority: add an element to the queue with an associated
-   priority.
-
-3) pull_highest_priority_element: remove the element from the queue that
-   has the highest priority, and return it. If two elements have the same
-   priority, then return element added first.
-
-"
-
-My notes: At last, a nicely specified problem to implement a nice data
-type.  meat and drink to me!  I've split out the Priority Queue
-implementation into the module PQ.pm, minimally-OO in order to
-get free magic PQ printing via interpolation and the magic of
-stringification.
+My notes: Another clearly described problem.  Greedy algorithm wiki page
+just neans: fit words on the line while they fit:-)
diff --git a/challenge-019/duncan-c-white/perl5/ch-1.pl b/challenge-019/duncan-c-white/perl5/ch-1.pl
new file mode 100755
index 0000000000..e1c833054b
--- /dev/null
+++ b/challenge-019/duncan-c-white/perl5/ch-1.pl
@@ -0,0 +1,53 @@
+#!/usr/bin/perl
+#
+# Challenge 1: "Write a script to display months from the year 1900 to 2019
+# where you find 5 weekends i.e. 5 Friday, 5 Saturday and 5 Sunday."
+# 
+# My notes:
+# 
+# Clearly defined, although Friday isn't normally considered part of the
+# weekend is it?  Anyway, it's clear here that Friday - Sunday is the weekend
+# for the purposes of this question.  Date::Manip can do this easily enough.
+# 
+
+use strict;
+use warnings;
+use Function::Parameters;
+use List::Util qw(min);
+use Date::Manip;
+use Data::Dumper;
+
+die "Usage: ch-1.pl [STARTYEAR [ENDYEAR]]\n" if @ARGV>2;
+my $startyear = shift // 1900;
+my $endyear = shift // 2019;
+
+#
+# my $n = threedayweekends( $year, $month );
+#	Find how many three day weekends (Friday, Saturday and Monday)
+#	there are in month $month (1..12) in year $year.
+#
+fun threedayweekends( $year, $month )
+{
+	my $nfri = 0;
+	my $nsat = 0;
+	my $nsun = 0;
+	my $ndays = Date_DaysInMonth( $month,$year );
+	foreach my $dayno (1..$ndays)
+	{
+		my $day = Date_DayOfWeek( $month, $dayno, $year );
+		$nfri++ if $day == 5;
+		$nsat++ if $day == 6;
+		$nsun++ if $day == 7;
+	}
+	return min( $nfri, $nsat, $nsun );
+}
+
+
+foreach my $y ($startyear..$endyear)
+{
+	foreach my $m (1..12)
+	{
+		my $n = threedayweekends( $y, $m );
+		printf "%02d/$y $n three day weekends\n", $m if $n==5;
+	}
+}
diff --git a/challenge-019/duncan-c-white/perl5/ch-2.pl b/challenge-019/duncan-c-white/perl5/ch-2.pl
new file mode 100755
index 0000000000..cbf1672f0e
--- /dev/null
+++ b/challenge-019/duncan-c-white/perl5/ch-2.pl
@@ -0,0 +1,37 @@
+#!/usr/bin/perl
+#
+# Challenge 2: "Write a script that can wrap the given paragraph at a specified
+# column using the greedy algorithm."
+# 
+# My notes: Another clearly described problem.  Greedy algorithm wiki page
+# just neans: fit words on the line while they fit:-)
+# 
+
+use strict;
+use warnings;
+use Function::Parameters;
+use Data::Dumper;
+
+die "Usage: ch-2.pl width sentence\n" if @ARGV<2;
+my $linelen = shift;
+my $sentence = join( ' ', @ARGV );
+
+my @words = split(/\s+/,$sentence);
+my $line = shift @words;
+my $linew = length($line);
+
+foreach my $word (@words)
+{
+	my $len = length($word);
+	if( $linew + $len + 1 < $linelen )
+	{
+		$line .= " $word";
+		$linew += $len+1;
+	} else
+	{
+		print "$line\n";
+		$line = $word;
+		$linew = $len;
+	}
+}
+print "$line\n" if $line;