update

Task/Five-weekends/Racket/five-weekends-1.rkt

@@ -0,0 +1,26 @@
+#lang racket
+(require srfi/19)
+
+(define long-months '(1 3 5 7 8 10 12))
+(define days #(sun mon tue wed thu fri sat))
+
+(define (week-day date)
+  (vector-ref days (date-week-day date)))
+
+(define (five-weekends-a-month start end)
+  (for*/list ([year (in-range start (+ end 1))]
+              [month long-months]
+              [date (in-value (make-date 0 0 0 0 31 month year 0))]
+              #:when (eq? (week-day date) 'sun))
+    date))
+
+(define weekends (five-weekends-a-month 1900 2100))
+(define count (length weekends))
+
+(displayln (~a "There are " count " weeks with five weekends."))
+(displayln "The first five are: ")
+(for ([w (take weekends 5)])
+  (displayln (date->string w "~b ~Y")))
+(displayln "The last five are: ")
+(for ([w (drop weekends (- count 5))])
+  (displayln (date->string w "~b ~Y")))

Task/Five-weekends/Racket/five-weekends-2.rkt

@@ -0,0 +1,13 @@
+There are 201 weeks with five weekends.
+The first five are:
+Mar 1901
+Aug 1902
+May 1903
+Jan 1904
+Jul 1904
+The last five are:
+Mar 2097
+Aug 2098
+May 2099
+Jan 2100
+Oct 2100

Task/Five-weekends/Ruby/five-weekends.rb

@@ -9,9 +9,9 @@ dates = (start..stop).find_all do |day|
 end
 
 puts "There are #{dates.size} months with 5 weekends from 1900 to 2100:"
-puts dates[0, 5].map { |d| d.strftime("%b %Y") }.join("\n")
+puts dates.first(5).map { |d| d.strftime("%b %Y") }
 puts "..."
-puts dates[-5, 5].map { |d| d.strftime("%b %Y") }.join("\n")
+puts dates.last(5).map { |d| d.strftime("%b %Y") }
 
 years_with_5w = dates.map(&:year)