Remove dependence on Date::Calc

2 files changed, 63 insertions, 16 deletions

diff --git a/challenge-013/paulo-custodio/perl/ch-1.pl b/challenge-013/paulo-custodio/perl/ch-1.pl
index 132cbde073..facf356a55 100644
--- a/challenge-013/paulo-custodio/perl/ch-1.pl
+++ b/challenge-013/paulo-custodio/perl/ch-1.pl
@@ -22,15 +22,40 @@
 use strict;
 use warnings;
 use 5.030;
-use Date::Calc 'Nth_Weekday_of_Month_Year';
+use constant Friday => 5;
 
-our $Friday = 5;
+sub is_leap {
+	my($year) = @_;
+	return ((($year % 4)==0 && ($year % 100)!=0) || ($year % 400)==0) ? 1 : 0;
+}
+
+sub days_in_month {
+	my($year, $month) = @_;
+	my @dom = (31, 28+is_leap($year), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
+	return $dom[$month-1];
+}
+
+sub day_of_year {
+	my($year, $month, $day) = @_;
+	my $dayno = $day; 
+	$dayno += days_in_month($year, $_) for (1 .. $month-1);
+	return $dayno;
+}
+
+# return 1..7 <=> Monday..Sunday
+sub day_of_week {
+	my($year, $month, $day) = @_;
+	my $dayno = day_of_year($year, $month, $day);
+	my $wdnog = ($dayno + $year + int(($year-1)/4) - int(($year-1)/100) 
+				 + int(($year-1)/400) - 2) % 7 + 1;
+	return $wdnog;
+}
 
 sub last_friday {
-	my($year,$month) = @_;
-	for my $n (reverse 1..5) {
-		if (my($y,$m,$d) = Nth_Weekday_of_Month_Year($year,$month,$Friday,$n)) {
-			return ($y,$m,$d);
+	my($year, $month) = @_;
+	for my $day (reverse 1 .. days_in_month($year, $month)) {
+		if (day_of_week($year, $month, $day) == Friday) {
+			return ($year, $month, $day);
 		}
 	}
 }
diff --git a/challenge-019/paulo-custodio/perl/ch-1.pl b/challenge-019/paulo-custodio/perl/ch-1.pl
index 2dd314bf0a..af94bada70 100644
--- a/challenge-019/paulo-custodio/perl/ch-1.pl
+++ b/challenge-019/paulo-custodio/perl/ch-1.pl
@@ -5,16 +5,41 @@
 # Task #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.
+#
+# Solution: 4 weeks are 28 days, to have 5 week-ends we need additional 3 days (29,30,31),
+# therefore 31st must be a Sunday
 
 use strict;
 use warnings;
 use 5.030;
-use Date::Calc qw( Nth_Weekday_of_Month_Year );
-use constant {
-	Friday => 5,
-	Saturday => 6,
-	Sunday => 7 
-};
+use constant Sunday => 7;
+
+sub is_leap {
+	my($year) = @_;
+	return ((($year % 4)==0 && ($year % 100)!=0) || ($year % 400)==0) ? 1 : 0;
+}
+
+sub days_in_month {
+	my($year, $month) = @_;
+	my @dom = (31, 28+is_leap($year), 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
+	return $dom[$month-1];
+}
+
+sub day_of_year {
+	my($year, $month, $day) = @_;
+	my $dayno = $day; 
+	$dayno += days_in_month($year, $_) for (1 .. $month-1);
+	return $dayno;
+}
+
+# return 1..7 <=> Monday..Sunday
+sub day_of_week {
+	my($year, $month, $day) = @_;
+	my $dayno = day_of_year($year, $month, $day);
+	my $wdnog = ($dayno + $year + int(($year-1)/4) - int(($year-1)/100) 
+				 + int(($year-1)/400) - 2) % 7 + 1;
+	return $wdnog;
+}
 
 for my $year (1900 .. 2019) {
 	for my $month (1 .. 12) {
@@ -25,8 +50,5 @@ for my $year (1900 .. 2019) {
 
 sub five_weekends {
 	my($year, $month) = @_;
-	return unless Nth_Weekday_of_Month_Year($year, $month, Friday, 5);
-	return unless Nth_Weekday_of_Month_Year($year, $month, Saturday, 5);
-	return unless Nth_Weekday_of_Month_Year($year, $month, Sunday, 5);
-	return 1;
+	return days_in_month($year, $month)==31 && day_of_week($year, $month, 31)==Sunday;
 }