solutions for challenge 013

3 files changed, 73 insertions, 0 deletions

diff --git a/challenge-013/adam-russell/blog.txt b/challenge-013/adam-russell/blog.txt
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+++ b/challenge-013/adam-russell/blog.txt
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+https://adamcrussell.livejournal.com/4730.html
diff --git a/challenge-013/adam-russell/perl5/ch-1.pl b/challenge-013/adam-russell/perl5/ch-1.pl
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+++ b/challenge-013/adam-russell/perl5/ch-1.pl
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+use strict;
+use warnings;
+##
+# Write a script to print the date of last Friday of every month of a given year.
+##
+use constant YEAR => 2019; 
+use constant FRIDAY => 5; 
+use constant JANUARY => 1;
+use constant FEBRUARY => 2;
+use constant MARCH => 3;
+use constant APRIL => 4;
+use constant MAY => 5;
+use constant JUNE => 6;
+use constant JULY => 7;
+use constant AUGUST => 8;
+use constant SEPTEMBER => 9;
+use constant OCTOBER => 10;
+use constant NOVEMBER => 11;
+use constant DECEMBER => 12;
+ 
+sub day_of_week{
+    my($year, $month, $day) = @_;
+    my @month_value = (0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4); 
+    $year-- if($month == JANUARY || $month == FEBRUARY);  
+    return ($year + int($year/4) - int($year/100) + int($year/400) + $month_value[$month-1] + $day) % 7
+}
+
+##
+# Main
+##
+my $is_leap_year = (((YEAR % 4) == 0) && ((YEAR % 100) != 0)) || ((YEAR % 4) == 0 && (YEAR % 400) == 0); 
+for my $m (JANUARY..DECEMBER){
+    my $last_friday; 
+    for my $d (20 .. 31){
+        last if($m == FEBRUARY && $d > 28 && !$is_leap_year);
+        last if($m == FEBRUARY && $d > 29 && $is_leap_year);
+        last if(($m == APRIL || $m == JUNE || $m == SEPTEMBER || $m == NOVEMBER) && $d > 30); 
+        my $dow = day_of_week(YEAR, $m, $d);
+        if($dow == FRIDAY){
+            $last_friday = $d;    
+        }   
+    }  
+    print YEAR . "/" . sprintf("%02d", $m) . "/$last_friday\n";
+} 
diff --git a/challenge-013/adam-russell/perl5/ch-2.pl b/challenge-013/adam-russell/perl5/ch-2.pl
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+++ b/challenge-013/adam-russell/perl5/ch-2.pl
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+use strict;
+use warnings;
+##
+# Using mutually recursive methods, generate Hofstadter Female and Male sequences.
+##
+
+sub F{
+    my($n) = @_;
+    if($n == 0){
+        return 1;  
+    } 
+    return $n - M(F($n - 1));  
+}
+
+sub M{ 
+    my($n) = @_;
+    if($n == 0){
+        return 0;  
+    }  
+    return $n - F(M($n - 1));  
+}
+
+##
+# Main
+## 
+for my $n (0 .. 25){  
+    print "$n\tM: " . M($n) . "\tF: " . F($n) . "\n";
+}