Merge pull request #1009 from dcw803/master

imported my solutions to challenge037

5 files changed, 788 insertions, 18 deletions

diff --git a/challenge-037/duncan-c-white/README b/challenge-037/duncan-c-white/README
index fff0e6a452..c71e2a54c9 100644
--- a/challenge-037/duncan-c-white/README
+++ b/challenge-037/duncan-c-white/README
@@ -1,27 +1,59 @@
-Challenge 1: "Write a program to validate a given Vehicle Identification Number
-  (VIN). For more information, please checkout
-  https://en.wikipedia.org/wiki/Vehicle_identification_number
+Challenge 1: "Write a script to calculate the total number of weekdays (Mon-Fri) in each month of the year 2019.
+Jan: 23 days
+Feb: 20 days
+Mar: 21 days
+Apr: 22 days
+May: 23 days
+Jun: 20 days
+Jul: 23 days
+Aug: 22 days
+Sep: 21 days
+Oct: 23 days
+Nov: 21 days
+Dec: 22 days
 "
 
-My notes:  sounds rather tedious, lots of tables of codes, and optional
-bits only enforced in some countries. Do we have to validate all the
-optional bits?
+My notes: sounds rather straightforward, with or without date manipulation
+modules.  Might even have a crack at this in an unconventional language
+as well as Perl - how about Adobe Postscript?
 
+Afternotes: I did 3 versions of this:
 
-Challenge 2: "Write a program to solve the Knapsack Problem.
+ch-1-Date-Manip.pl: first version uses Date::Manip's Date_DaysInMonth(m,y) and
+		    Date_DayOfWeek(m,d,y) functions.
 
-There are 5 color coded boxes with varying weights and amounts in
-GBP. Which boxes should be choosen to maximize the amount of money while
-still keeping the overall weight under or equal to 15 kgs?
+ch-1.pl:	    second version does it ourselves from scratch.
 
-R: (weight = 1 kg, amount = £1)
-B: (weight = 1 kg, amount = £2)
-G: (weight = 2 kg, amount = £2)
-Y: (weight = 12 kg, amount = £4)
-P: (weight = 4 kg, amount = £10)
+ch-1-in-postscript.ps: translated ch-1.pl into Postscript.  Yes, the language
+		       mostly used for printer page layout, can be used as a
+		       full-blown programming language.  However, you have to
+		       include functions to append strings and produce a
+		       variety of debugging messages down the page, before
+		       you start on the actual program logic.
 
-Bonus task, what if you were allowed to pick only 2 boxes or 3 boxes or
-4 boxes? Find out which combination of boxes is the most optimal?
+
+Challenge 2: "Write a script to find out the DayLight gain/loss in
+the month of December 2019 as compared to November 2019 in the city of
+London. You can find out London sunrise and sunset data for November 2019 here:
+https://www.timeanddate.com/sun/uk/london?month=11&year=2019
+
+and for December 2019 here:
+https://www.timeanddate.com/sun/uk/london?month=12&year=2019
 "
 
-My notes: sounds interesting!
+My notes: most of this problem is fetching the web pages and parsing the
+information out of the first table in each page: that's a typical
+HTML::Parser state machine, easy enough.  But once we have that information,
+eg. for each month a day->daylight duration mapping, what exactly does the
+question mean us to do?  
+
+I think this problem means
+
+"calculate the difference between the amount of daylight on 1st Nov and on
+30th Nov, do the same for December (1st and 31st), and find out which
+"within month daylight duration" is smaller."
+
+btw, if I'm right the smaller duration is obviously between 1st-31st Dec
+than between 1st-30th Nov, because in November the days are getting shorter
+throughout the whole month, whereas in December they get shorter from
+1st-21st Dec, and then get longer again!
diff --git a/challenge-037/duncan-c-white/perl5/ch-1-Date-Manip.pl b/challenge-037/duncan-c-white/perl5/ch-1-Date-Manip.pl
new file mode 100755
index 0000000000..83fa046f5e
--- /dev/null
+++ b/challenge-037/duncan-c-white/perl5/ch-1-Date-Manip.pl
@@ -0,0 +1,58 @@
+#!/usr/bin/perl
+#
+# Challenge 1: "Write a script to calculate the total number of weekdays (Mon-Fri) in each month of the year 2019.
+# Jan: 23 days
+# Feb: 20 days
+# Mar: 21 days
+# Apr: 22 days
+# May: 23 days
+# Jun: 20 days
+# Jul: 23 days
+# Aug: 22 days
+# Sep: 21 days
+# Oct: 23 days
+# Nov: 21 days
+# Dec: 22 days
+# "
+# 
+# My notes: sounds rather straightforward, with or without date manipulation
+# modules.  This first version uses Date::Manip's Date_DaysInMonth(m,y) and
+# Date_DayOfWeek(m,d,y) functions.
+# 
+
+use v5.10;	# to get "say"
+use strict;
+use warnings;
+use Function::Parameters;
+use Date::Manip;
+
+
+die "Usage: ch-1.pl [YEAR]\n" if @ARGV>1;
+
+my @month = qw(X Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
+
+
+#
+# my $n = countweekdays( $y, $m );
+#	Find how many week days (Monday..Friday) there are in month $month
+#	(1..12) in year $y.
+#
+fun countweekdays( $year, $month )
+{
+	my $n = 0;
+	my $ndays = Date_DaysInMonth( $month,$year );
+	foreach my $dayno (1..$ndays)
+	{
+		my $day = Date_DayOfWeek( $month, $dayno, $year );
+		$n++ if $day < 6;
+	}
+	return $n;
+}
+
+
+my $y = shift // 2019;
+foreach my $m (1..12)
+{
+	my $n = countweekdays( $y, $m );
+	print $month[$m], " $y: $n weekdays\n";
+}
diff --git a/challenge-037/duncan-c-white/perl5/ch-1-in-postscript.ps b/challenge-037/duncan-c-white/perl5/ch-1-in-postscript.ps
new file mode 100644
index 0000000000..ae7c894215
--- /dev/null
+++ b/challenge-037/duncan-c-white/perl5/ch-1-in-postscript.ps
@@ -0,0 +1,355 @@
+%!PS-Adobe-3.0
+%%Pages: 1
+%%EndComments
+%
+% ch-1-in-postscript.ps: translated ch-1.pl into Postscript.
+%
+% Yes, the language mostly used for printer page layout, can be used as a
+% full-blown programming language.  However, you have to include functions
+% to append strings and produce a variety of debugging messages down the
+% page, before you start on the actual program logic.
+%
+% Debugging....
+
+% const debuglm: left margin of debug messages
+/debuglm 0.5 72 mul def
+
+% const debugtop: top of debug messages - 11 inches up.
+/debugtop 11 72 mul def
+
+% const debugdown: how far to go down each line
+/debugdown 20 def
+
+
+% debugorigin():
+%	 move to debugging origin
+/debugorigin
+{
+	debuglm debugtop moveto
+	(Debugging log:) show
+	newline
+} bind def
+
+
+% debugn( name );
+%	display a single string $name on a debug line.
+/debugn
+{
+	30 0 rmoveto
+	show		% show name
+	newline
+} bind def
+
+
+% debugnv( name, value );
+%	display name and value on a debug line.
+%	keep this as it's so much simpler than debug() below
+%	and also debug() has commented out invocations to
+%	this throughout it:-)
+/debugnv
+{
+	% initially: stack top: value, name
+	30 0 rmoveto
+	exch		% stack top: name, value
+	show		% show name, stack top: value
+	(: ) show
+	50 string cvs show	% show convert_to_string(value)
+	newline
+} bind def
+
+
+% debug( array_of_pairs );
+%	display a single message, combining every pair of items (name,value)
+%	in <array> as name: value, and comma-separating them.
+%	eg debug( [(x) x (y) y (z) z] ) produces
+%	"x: value_of_x, y: value_of_y, z: value_of_z"
+%	(whether or not the values are strings or integers)
+/debug
+{
+    6 dict begin	% next N items defined are in a local dictionary
+	/array exch def % localize parameter name, removing it from stack
+	/len 0 def	% local variable - length of array
+	/pos 0 def	% local variable - position in array
+	/name () def	% local variable - an array element
+	/value () def	% local variable - next array element
+	/first 1 def	% local variable - first time round loop?
+
+	30 0 rmoveto
+
+	/len array length def
+
+	%Perl for pos = 0 to $#array step 2
+	0 2 len 1 sub
+	{
+		/pos exch def
+
+		%Perl $name = $array[$pos];
+		/name array pos get def
+
+		%Perl $value = $array[$pos+1];
+		/value array pos 1 add get def
+
+		%Perl print "," unless first
+		first 0 eq {
+			(, ) show
+		} if
+
+		%Perl print "$name: $value";
+		name 50 string cvs show
+		(: ) show
+		value 50 string cvs show
+
+		%Perl $first=0;
+		/first 0 def
+	} for
+
+	newline
+
+    end		% local dictionary destroyed here
+
+} def
+
+
+% newline();
+%	go to left margin of next line for debug messages
+/newline
+{
+	currentpoint debugdown sub % decrement Y pos
+	exch pop		% drop old X
+	debuglm exch		% form (debuglm,Y) on stack
+	moveto			% go there!
+} def
+
+
+% result = append( string1, string2 )
+% 	Concatenates two strings together.  Some languages
+%	already know how to do stuff like this!!!
+/append
+{
+	 % Initial stack: s1 s2 <-- top of stack
+         2 copy		% s1 s2 s1 s2
+	 length		% s1 s2 s1 len(s2)
+	 exch		% s1 s2 len(s2) s1
+	 length add	% s1 s2 len(s1)+len(s2)
+         string dup     % s1 s2 r r
+         4 2 roll       % r r s1 s2
+         2 index	% r r s1 s2 r
+	 0		% r r s1 s2 r 0
+	 3 index	% r r s1 s2 r 0 s1
+         putinterval    % strcpy( r+0, s1 )
+         		% r r s1 s2
+         exch		% r r s2 s1
+	 length		% r r s2 len(s1)
+	 exch		% r r len(s1) s2
+	 putinterval	% strcpy( r+len(s1), s2 )
+	 		% return r
+} bind def
+
+
+% isleap = isleapyear( y );
+%	Return 1 if year $y is a leap year; 0 if not.
+%
+%Perl code:	return 0 if y % 4 != 0;
+%Perl code:	return 1 if y % 100 != 0;
+%Perl code:	return 0 if y % 400 != 0;
+%Perl code:	return 1;
+%
+/isleapyear
+{
+    2 dict begin	% next N items defined are in a local dictionary
+	/y exch def	% localize parameter name, removing it from stack
+	/isleap 0 def	% local variable - the return value, boolean
+
+	%[ (debug: is leap year y) y (isleap) isleap ] debug
+
+	% if y%4 == 0 then
+	y 4 mod 0 eq {          % 1st if..then
+	     % if y%100 != 0 then isleap=1..
+	     y 100 mod 0 ne {
+		 /isleap 1 def
+	% else  [y%100 == 0]
+	} {
+		 % isleap=1 if y%400 == 0
+		 y 400 mod 0 eq {
+		      /isleap 1 def
+	         } if
+	     } ifelse
+	} if
+
+	isleap		% leave result on stack
+
+    end		% local dictionary destroyed here
+} def
+
+
+% dow = dayofweek1stjanyear( year );
+%	Find and return the day-of-the-week
+%	(0=Monday, 1=Tuesday.. 4=Friday, 5=Saturday, 6=Sunday)
+%	of 1st Jan $year (only valid for year>=1900).
+%
+/dayofweek1stjanyear
+{
+    4 dict begin	% next N items defined are in a local dictionary
+	/year exch def	% localize parameter name, removing it from stack
+	/dow 0 def	% local variable: day-of-week, return value
+			% why initial value 0?  1st Jan 1900 was Monday==0..
+	/y 0 def	% local variable: for loop variable
+	/days 0 def	% local variable: how many days to add (2 in leap years, 1 otherwise)
+
+	% year--
+	year 1 sub /year exch def
+
+	% foreach my $y (1900..$year)
+	% {
+	1900 1 year
+	{
+		/y exch def
+%		(y) y debugnv
+
+		/days y isleapyear 1 add def
+%		(days) days debugnv
+
+%		%print "$y: advance $days days\n";
+%		(y:) y 50 string cvs append (: advance ) append
+%		days 50 string cvs append ( days) debugnv
+
+		% dow = (dow + days) % 7;
+		dow days add 7 mod /dow exch def
+
+%		% print "dow=$dow"
+%		(dow) dow debugnv
+	% }
+	} for
+
+	dow	% leave value on stack
+
+    end		% local dictionary destroyed here
+} def
+
+
+%
+% mdays = daysinmonth( m, isleap );
+%	Return the number of days in month $m (0..11), adjusting
+%	number of days in February is $isleap is true.
+%
+/daysinmonth
+{
+    3 dict begin	% next N items defined are in a local dictionary
+	/isleap exch def% parameter - boolean, are we in a leap year?
+	/m exch def	% parameter - month number 0..11
+	/d 0 def	% local variable
+
+	%Perl my @d = (31,28,31,30,31,30,31,31,30,31,30,31);
+	/d [31 28 31 30 31 30 31 31 30 31 30 31] def
+
+	%Perl $d[1]=29  if $isleap;
+	isleap 1 eq {
+		d 1 29 put
+	} if
+
+	%Perl return $d[$m];
+	d m get
+
+    end		% local dictionary destroyed here
+} def
+
+
+% showweekdays( $y );
+%	Show each month in year $y and the number of week days (Monday-Friday)
+%	in that month.
+%
+/showweekdays
+{
+    8 dict begin	% next N items defined are in a local dictionary
+	/y exch def	% parameter - the year
+	/isleap 0 def	% local variable - boolean, is $y a leap year?
+	/dow 0 def	% local variable - day-of-week: 0..6
+	/m 0 def	% local variable - month: 0..11
+	/mdays 0 def	% local variable - number of days in month $m
+	/monthname 0 def% local variable - name of month $m
+	/weekdays 0 def	% local variable - number of week days in month $m
+	/d 0 def	% local variable - day number 1..$mdays
+
+	%Perl my @monthname = qw(Jan Feb Mar Apr May Jun Jul
+	%Perl			 Aug Sep Oct Nov Dec);
+	/monthname [(Jan) (Feb) (Mar) (Apr) (May) (Jun) (Jul)
+		    (Aug) (Sep) (Oct) (Nov) (Dec)] def
+
+	%Perl my $isleap = isleapyear( $y );
+	/isleap y isleapyear def
+
+	%#Perl print "isleap[ $y ]: $isleap\n";
+	%(isleap[ ) y 50 string cvs append ( ] ) append isleap debugnv
+
+	%Perl my $dow = dayofweek1stjanyear( $y );
+	/dow y dayofweek1stjanyear def
+
+	%#Perl print "day-of-week[ 1st Jan $year ]: $dow\n";
+	%(day-of-week[ 1st Jan ) y 50 string cvs append ( ] ) append dow debugnv
+
+	%Perl foreach my $m (0..11)
+	%Perl {
+	0 1 11
+	{
+		/m exch def
+
+		%Perl 	my $mdays = daysinmonth( $m, $isleap );
+		/mdays m isleap daysinmonth def
+
+		%Perl  my $mname = monthname[m];
+		/mname monthname m get def
+		%(monthname) mname debugnv
+
+		%#Perl 	print "days in month[$mname, " $y]: $mdays\n";
+		%(days in month[) mname append
+		%( ) append
+		%y 50 string cvs append
+		%(]) append
+		%mdays debugnv
+
+		%Perl 	my $weekdays = 0;
+		/weekdays 0 def
+
+		%Perl 	foreach my $d (1..$mdays)
+		%Perl 	{
+		1 1 mdays
+		{
+			/d exch def
+			%[ (d) d (dow) dow (weekdays) weekdays ] debug
+
+			%Perl 		$weekdays++ if $dow < 5;
+			dow 5 lt {
+				weekdays 1 add /weekdays exch def
+			} if
+
+			% dow = (dow + 1) % 7;
+			dow 1 add 7 mod /dow exch def
+
+		%Perl 	}
+		} for
+
+		%Perl 	print "$mname $y: $weekdays weekdays\n";
+		mname ( ) append
+		y 50 string cvs append
+		(: ) append
+		weekdays 50 string cvs append
+		( weekdays) append
+		debugn
+
+	%Perl }
+	} for
+
+    end		% local dictionary destroyed here
+} def
+
+
+%%Page: 1 1
+%%PageOrientation: Portrait
+
+/Helvetica-Bold findfont 13 scalefont setfont
+
+debugorigin
+
+2019 showweekdays
+
+showpage
diff --git a/challenge-037/duncan-c-white/perl5/ch-1.pl b/challenge-037/duncan-c-white/perl5/ch-1.pl
new file mode 100755
index 0000000000..d149d0116c
--- /dev/null
+++ b/challenge-037/duncan-c-white/perl5/ch-1.pl
@@ -0,0 +1,97 @@
+#!/usr/bin/perl
+#
+# Challenge 1: "Write a script to calculate the total number of weekdays (Mon-Fri) in each month of the year 2019.
+# Jan 2019: 23 weekdays
+# Feb 2019: 20 weekdays
+# Mar 2019: 21 weekdays
+# Apr 2019: 22 weekdays
+# May 2019: 23 weekdays
+# Jun 2019: 20 weekdays
+# Jul 2019: 23 weekdays
+# Aug 2019: 22 weekdays
+# Sep 2019: 21 weekdays
+# Oct 2019: 23 weekdays
+# Nov 2019: 21 weekdays
+# Dec 2019: 22 weekdays
+# "
+# 
+# My notes: sounds rather straightforward, even without date manipulation
+# modules.  This second version does it ourselves from scratch.
+# 
+
+use v5.10;	# to get "say"
+use strict;
+use warnings;
+use Function::Parameters;
+
+
+die "Usage: ch-1.pl [YEAR]\n" if @ARGV>1;
+
+my @month = qw(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec);
+
+
+#
+# my $isleap = isleapyear( $y );
+#	Return 1 if year $y is a leap year; 0 if not.
+#
+fun isleapyear( $y )
+{
+	return 0 unless $y % 4 == 0;
+	return 1 unless $y % 100 == 0;
+	return 0 unless $y % 400 == 0;
+	return 1;
+}
+
+
+#
+# my $dow = dayofweek1stjanyear( $y );
+#	Find the day-of-the-week
+#	(0=Monday, 1=Tuesday.. 4=Friday, 5=Saturday, 6=Sunday)
+#	of 1st Jan $y (only valid for y>=1900).  Return it.
+#
+fun dayofweek1stjanyear( $y )
+{
+	# first, calculate dow in range 0..6
+	my $dow = 0;	# 1st Jan 1900 was a Monday..
+	foreach my $y (1900..$y-1)
+	{
+		my $days = isleapyear($y) ? 2 : 1;
+		#print "$y: advance $days days\n";
+		$dow += $days;
+		$dow %= 7;
+	}
+	return $dow;
+}
+
+
+#
+# my $daysinmonth = daysinmonth( $m, $isleap );
+#	Return the number of days in month $m (0..11), adjusting
+#	number of days in February is $isleap is true.
+#
+fun daysinmonth( $m, $isleap )
+{
+	my @d = (31,28,31,30,31,30,31,31,30,31,30,31);
+	$d[1]=29  if $isleap;
+	return $d[$m];
+}
+
+
+my $y = shift // 2019;
+my $isleap = isleapyear( $y );
+my $dow = dayofweek1stjanyear( $y );
+#print "1st Jan $y is day-of-week $dow\n";
+
+foreach my $m (0..11)
+{
+	my $daysinmonth = daysinmonth( $m, $isleap );
+	#print $month[$m], " $y: had $daysinmonth days\n";
+	my $weekdays = 0;
+	foreach my $d (1..$daysinmonth)
+	{
+		$weekdays++ if $dow < 5;
+		$dow++;
+		$dow %= 7;
+	}
+	print $month[$m], " $y: $weekdays weekdays\n";
+}
diff --git a/challenge-037/duncan-c-white/perl5/ch-2.pl b/challenge-037/duncan-c-white/perl5/ch-2.pl
new file mode 100755
index 0000000000..678f899a39
--- /dev/null
+++ b/challenge-037/duncan-c-white/perl5/ch-2.pl
@@ -0,0 +1,228 @@
+#!/usr/bin/perl
+#
+# Challenge 2: "Write a script to find out the DayLight gain/loss in
+# the month of December 2019 as compared to November 2019 in the city of
+# London. You can find out London sunrise and sunset data for November 2019 here:
+# https://www.timeanddate.com/sun/uk/london?month=11&year=2019
+# 
+# and for December 2019 here:
+# https://www.timeanddate.com/sun/uk/london?month=12&year=2019
+# "
+# 
+# My notes: most of this problem is fetching the web pages and parsing the
+# information out of the first table in each page: that's a typical
+# HTML::Parser state machine, easy enough.  But once we have that information,
+# eg. for each month a day->daylight duration mapping, what exactly does the
+# question mean us to do?  
+# 
+# I think this problem means
+# 
+# "calculate the difference between the amount of daylight on 1st Nov and on
+# 30th Nov, do the same for December (1st and 31st), and find out which
+# "within month daylight duration" is smaller."
+# 
+# btw, if I'm right the smaller duration is obviously between 1st-31st Dec
+# than between 1st-30th Nov, because in November the days are getting shorter
+# throughout the whole month, whereas in December they get shorter from
+# 1st-21st Dec, and then get longer again!
+# 
+
+use v5.10;	# to get "say"
+use strict;
+use warnings;
+use Function::Parameters;
+use LWP::Simple;
+use HTML::Parser;
+use File::Slurp;
+use Time::Piece;
+use Data::Dumper;
+
+my $novurl = "https://www.timeanddate.com/sun/uk/london?month=11&year=2019";
+my $decurl = "https://www.timeanddate.com/sun/uk/london?month=12&year=2019";
+
+
+my $debug_parse=0;
+
+fun start( $t, $p )
+{
+	print "start<$t>\n" if $debug_parse;
+	#print Dumper($p) if $debug_parse;
+	#die;
+	if( $t eq "table" )
+	{
+		$p->{tableno}++;
+		print "in table $p->{tableno}, want_table = $p->{want_table}\n" if $debug_parse;
+		$p->{inwantedtable} =
+			($p->{tableno} == $p->{want_table}) ? 1 : 0;
+		return unless $p->{inwantedtable};
+		print "in wanted table: table $p->{tableno}\n" if $debug_parse;
+		$p->{rowno} = -1;
+		return;
+	}
+	if( $p->{inwantedtable} && $t eq "tr" )
+	{
+		$p->{rowno}++;
+		print "in wanted table: table $p->{tableno}, row $p->{rowno}\n" if $debug_parse;
+		$p->{colno} = -1;
+		$p->{row} = [];
+		return;
+	}
+	if( $p->{inwantedtable} && $t =~ /^(td|th)$/ )
+	{
+		$p->{colno}++;
+		print "in wanted table: table $p->{tableno}, ".
+		      "row $p->{rowno}, column $p->{colno}\n" if $debug_parse;
+		$p->{inwantedcell} =
+			$p->{want_columns}->{ $p->{colno} } ? 1 : 0;
+		if( $p->{inwantedcell} )
+		{
+			print "capturing wanted cell column $p->{colno} in ".
+			      "row $p->{rowno}\n" if $debug_parse;
+			$p->{celltext} = '';
+		}
+	}
+}
+
+
+fun text( $t, $p )
+{
+	return unless $p->{inwantedcell};
+	print "text<$t> in wanted cell\n" if $debug_parse;
+	$t =~ s/^\s+//m;
+	$t =~ s/\s+$//m;
+	$p->{celltext} .= $t;
+	print "debug: text: <<$t>>, celltext after: <<$p->{celltext}>>\n" if $debug_parse;
+}
+
+
+fun end( $t, $p )
+{
+	print "end<$t>\n" if $debug_parse;
+	if( $t eq "table" )
+	{
+		print "leaving table $p->{tableno}\n" if $debug_parse;
+		$p->{inwantedtable} = 0;
+		$p->{inwantedcell} = 0;
+	} elsif( $p->{inwantedcell} && $t =~ /^(td|th)$/ )
+	{
+		$p->{inwantedcell} = 0;
+		push @{$p->{row}}, $p->{celltext};
+		print "at end of wantedcell, celltext=$p->{celltext}, row=", Dumper($p->{row}) if $debug_parse;
+		$p->{celltext} = '';
+	} elsif( $p->{inwantedtable} && $t eq "tr" )
+	{
+		push @{$p->{info}}, [ @{$p->{row}} ] if @{$p->{row}};
+		print "ending row in wantedtable: p->{info} is ", Dumper( $p->{info} ) if $debug_parse;
+		$p->{row} = [];
+		$p->{colno} = -1;
+		$p->{inwantedcell} = 0;
+	}
+}
+
+
+#
+# my %info = parse_table( $htmltext, %want );
+#	Given an HTML page $htmltext, and a specification of what parts
+#	of what table we want, find and parse the corresponding table,
+#	extract the wanted columns of each row, and build and return @info:
+#	an array of [ those column values ] tuples.
+#
+fun parse_table( $htmltext, %want )
+{
+	my $p = HTML::Parser->new( api_version => 3,
+				   start_h       => [\&start, "tagname, self"],
+				   end_h         => [\&end,   "tagname, self"],
+				   text_h        => [\&text,  "dtext, self"],
+				   unbroken_text => 1,
+				 );
+
+	$p->{want_table}    = $want{tableno};	# which table we want..
+
+						# set of which columns we want
+	$p->{want_columns} = { map { $_ => 1 } @{$want{columns}} };
+	#die Dumper $p->{want_columns};
+
+	$p->{tableno}       = -1;		# how many tables seen so far?
+	$p->{inwantedtable} = 0;		# are we in the WANTED table?
+	$p->{colno}         = -1;		# which column in now?
+	$p->{rowno}         = -1;		# which row no we're in now?
+	$p->{inwantedcell}  = 0;		# want this table cell?
+	$p->{celltext}      = '';		# cell text we're building
+	$p->{row}           = [];		# row we're building
+	$p->{info}          = [];		# the answer - list of rows
+
+	#die Dumper $p;
+
+	# Parse document text
+	$p->parse($htmltext);
+
+	my @result = @{$p->{info}};
+
+	$p->eof;                 # signal end of document
+
+	return @result;
+}
+
+
+#
+# my( $diff, $diffms ) = duration( $name, @month );
+#	Given a month info array for month $name, a list of
+#	[ dayno, dayduration ] pairs, calculate the difference in
+#	dayduration between the 1st dayno and the last.  Return it
+#	in two forms: as an integer (seconds) and as an mm{m}ss{s} string.
+#
+fun duration( $name, @month )
+{
+	my $first = $month[0][1];
+	print "\nduration 1st of $name: $first\n";
+	my $novdays = @month;
+	my $last = $month[$novdays-1][1];
+	print "duration last day in $name: $last\n";
+
+	my $t1 = Time::Piece->strptime( $last, '%H:%M:%S' );
+	my $t2 = Time::Piece->strptime( $first, '%H:%M:%S' );
+	my $diff = $t2 - $t1;
+
+	my $mins = int($diff/60);
+	my $secs = $diff%60;
+	my $hs = "${mins}m${secs}s";
+	print "$name diff: $diff ($hs)\n";
+
+	return( $diff, $hs );
+}
+
+
+my %want;
+$want{tableno}   = 0;		# want first table..
+$want{columns} = [ 0,3 ];	# which columns we want
+
+#my $html = read_file( "eg.html" );
+#my @info = parse_table( $html, %want );
+
+my $html = get($novurl) || die "can't get $novurl\n";
+my @nov = parse_table( $html, %want );
+
+# only want 2-tuples where both values start with a digit..
+@nov = grep { @$_ == 2 && $_->[0] =~ /^\d/ && $_->[1] =~ /^\d/ } @nov;
+
+$html = get($decurl) || die "can't get $decurl\n";
+my @dec = parse_table( $html, %want );
+
+# only want 2-tuples where both values start with a digit..
+@dec = grep { @$_ == 2 && $_->[0] =~ /^\d/ && $_->[1] =~ /^\d/ } @dec;
+
+#print "nov: ", Dumper \@nov;
+#print "dec: ", Dumper \@dec;
+
+my( $nd, $ndhs ) = duration( "Nov", @nov );
+my( $dd, $ddhs ) = duration( "Dec", @dec );
+
+print "\n";
+
+if( $nd < $dd )
+{
+	print "Nov diff smaller: $nd: $ndhs\n";
+} else
+{
+	print "Dec diff smaller: $dd: $ddhs\n";
+}