Data commit

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

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+require 'date'
+# The only case where the month has 5 weekends is when the last day
+# of the month falls on a Sunday and the month has 31 days.
+
+LONG_MONTHS = [1,3,5,7,8,10,12]
+YEARS       = (1900..2100).to_a
+
+dates    = YEARS.product(LONG_MONTHS).map{|y, m| Date.new(y,m,31)}.select(&:sunday?)
+years_4w = YEARS - dates.map(&:year)
+
+puts "There are #{dates.size} months with 5 weekends from 1900 to 2100:"
+puts dates.first(5).map {|d| d.strftime("%b %Y") }, "..."
+puts dates.last(5).map {|d| d.strftime("%b %Y") }
+puts "There are #{years_4w.size} years without months with 5 weekends:"
+puts years_4w.join(", ")