Another update from ingydotnet^djgoku

Task/Five-weekends/00META.yaml

@@ -1,5 +1,4 @@
 ---
 category:
-- Date and time
 - Puzzles
-note: Five weekends
+note: Date and time

Task/Five-weekends/CoffeeScript/five-weekends-1.coffee

@@ -0,0 +1,40 @@
+startsOnFriday = (month, year) ->
+  # 0 is Sunday, 1 is Monday, ... 5 is Friday, 6 is Saturday
+  new Date(year, month, 1).getDay() == 5
+
+has31Days = (month, year) ->
+  new Date(year, month, 31).getDate() == 31
+
+checkMonths = (year) ->
+  month = undefined
+  count = 0
+  month = 0
+  while month < 12
+    if startsOnFriday(month, year) and has31Days(month, year)
+      count += 1
+      console.log year + ' ' + month + ''
+    month += 1
+  count
+
+fiveWeekends = ->
+  startYear = 1900
+  endYear = 2100
+  year = undefined
+  monthTotal = 0
+  yearsWithoutFiveWeekends = []
+  total = 0
+  year = startYear
+  while year <= endYear
+    monthTotal = checkMonths(year)
+    total += monthTotal
+    # extra credit
+    if monthTotal == 0
+      yearsWithoutFiveWeekends.push year
+    year += 1
+  console.log 'Total number of months: ' + total + ''
+  console.log ''
+  console.log yearsWithoutFiveWeekends + ''
+  console.log 'Years with no five-weekend months: ' + yearsWithoutFiveWeekends.length + ''
+  return
+
+fiveWeekends()

Task/Five-weekends/CoffeeScript/five-weekends-2.coffee

@@ -0,0 +1,30 @@
+1901 2
+1902 7
+1903 4
+1904 0
+1904 6
+1905 11
+1907 2
+1908 4
+1909 0
+1909 9
+1910 6
+1911 11
+1912 2
+1913 7
+1914 4
+1915 0
+1915 9
+1916 11
+1918 2
+1919 7
+1920 9
+1921 6
+1922 11
+1924 7
+..
+
+Total number of months: 201
+1900,1906,1917,1923,1928,1934,1945,1951,1956,1962,1973,1979,1984,1990,2001,2007,2012,2018,2029,2035,2040,2046,2057,2063,2068,2074,2085,2091,2096
+
+Years with no five-weekend months: 29

Task/Five-weekends/Elixir/five-weekends.elixir

@@ -0,0 +1,18 @@
+defmodule Date do
+  @months { "January", "February", "March",     "April",   "May",      "June",
+            "July",    "August",   "September", "October", "November", "December" }
+
+  def five_weekends(year) do
+    for m <-[1,3,5,7,8,10,12], :calendar.day_of_the_week(year, m, 31) == 7, do: elem(@months, m-1)
+  end
+end
+
+months = Enum.map(1900..2100, fn year -> {year, Date.five_weekends(year)} end)
+{none, months5} = Enum.partition(months, fn {_,m} -> Enum.empty?(m) end)
+count = Enum.reduce(months5, 0, fn {year, months}, acc ->
+  IO.puts "#{year} : #{Enum.join(months, ", ")}"
+  acc + length(months)
+end)
+IO.puts "Found #{count} month with 5 weekends."
+IO.puts "\nFound #{length(none)} years with no month having 5 weekends:"
+IO.puts "#{inspect Enum.map(none, fn {y,_}-> y end)}"

Task/Five-weekends/Julia/five-weekends.julia

@@ -0,0 +1,26 @@
+isdefined(:Date) || using Dates
+
+const wday = Dates.Fri
+const lo = 1900
+const hi = 2100
+const showres = 5
+
+mfive = recur(Date(lo, 1):Month(1):Date(hi, 12)) do m
+    Dates.daysinmonth(m) == 31 && Dates.dayofweek(m) == wday
+end
+
+println("Considering the years from ", lo, " to ", hi, ".\n")
+println("There are ", length(mfive), " months having 5 3-day weekends.")
+
+println("The first ", showres, " such months are:")
+for m in mfive[1:showres]
+    println("    ", Dates.monthname(m), " ", Dates.year(m))
+end
+
+println("\nThe last ", showres, " such months are:")
+for m in mfive[end-showres+1:end]
+    println("    ", Dates.monthname(m), " ", Dates.year(m))
+end
+
+print("\nThere are ", length(filter(y -> !(y in year(mfive)), lo:hi)))
+println(" years that have no such months.")

Task/Five-weekends/Perl-6/five-weekends.pl6

@@ -1,11 +1,10 @@
 # A month has 5 weekends iff it has 31 days and starts on Friday.
 
 my @years = 1900 .. 2100;
-my @ym = @years X 1, 3, 5, 7, 8, 10, 12; # Months with 31 days
+my @has31 = 1, 3, 5, 7, 8, 10, 12;
+my @happy = ($_ when *.day-of-week == 5 for (@years X @has31).map(-> ($y, $m) { Date.new: $y, $m, 1 }));
 
-my @happy = @ym.map({ Date.new: $^a, $^b, 1 }).grep: { .day-of-week == 5 };
-
-say 'Happy month count:  ',  +@happy;
+say 'Happy month count:  ', +@happy;
 say 'First happy months: ' ~ @happy[^5];
 say 'Last  happy months: ' ~ @happy[*-5 .. *];
-say 'Dreary years count: ',  @years - @happy».year.uniq;
+say 'Dreary years count: ',  @years - @happy».year.squish;

Task/Five-weekends/PowerShell/five-weekends.psh

@@ -0,0 +1,20 @@
+$fiveWeekends = @()
+$yearsWithout = @()
+foreach ($y in 1900..2100) {
+  $hasFiveWeekendMonth = $FALSE
+  foreach ($m in @("01","03","05","07","08",10,12)) {
+    if ((Get-Date "$y-$m-1").DayOfWeek -eq "Friday") {
+      $fiveWeekends += "$y-$m"
+      $hasFiveWeekendMonth = $TRUE
+    }
+  }
+  if ($hasFiveWeekendMonth -eq $FALSE) {
+     $yearsWithout += $y
+  }
+}
+Write-Output "Between the years 1900 and 2100, inclusive, there are $($fiveWeekends.count) months with five full weekends:"
+Write-Output "$($fiveWeekends[0..4] -join ","),...,$($fiveWeekends[-5..-1] -join ",")"
+
+Write-Output ""
+Write-Output "Extra Credit: these $($yearsWithout.count) years have no such month:"
+Write-Output ($yearsWithout -join ",")

Task/Five-weekends/Scala/five-weekends.scala

@@ -0,0 +1,35 @@
+import java.util.Calendar._
+import java.util.GregorianCalendar
+
+import org.scalatest.{FlatSpec, Matchers}
+
+class FiveWeekends extends FlatSpec with Matchers {
+
+  case class YearMonth[T](year: T, month: T)
+  implicit class CartesianProd[T](val seq: Seq[T]) {
+    def x(other: Seq[T]) = for(s1 <- seq; s2 <- other) yield YearMonth(year=s1,month=s2)
+    def -(other: Seq[T]): Seq[T] = seq diff other
+  }
+
+  def has5weekends(ym: { val year: Int; val month: Int}) = {
+    val date = new GregorianCalendar(ym.year, ym.month-1, 1)
+    date.get(DAY_OF_WEEK) == FRIDAY && date.getActualMaximum(DAY_OF_MONTH) == 31
+  }
+
+  val expectedFirstFive = Seq(
+    YearMonth(1901,3), YearMonth(1902,8), YearMonth(1903,5), YearMonth(1904,1), YearMonth(1904,7))
+  val expectedFinalFive = Seq(
+    YearMonth(2097,3), YearMonth(2098,8), YearMonth(2099,5), YearMonth(2100,1), YearMonth(2100,10))
+  val expectedNon5erYears = Seq(1900, 1906, 1917, 1923, 1928, 1934, 1945, 1951, 1956, 1962,
+                                1973, 1979, 1984, 1990, 2001, 2007, 2012, 2018, 2029, 2035,
+                                2040, 2046, 2057, 2063, 2068, 2074, 2085, 2091, 2096)
+
+  "Five Weekend Algorithm" should "match specification" in {
+    val months = (1900 to 2100) x (1 to 12) filter has5weekends
+    months.size shouldBe 201
+    months.take(5) shouldBe expectedFirstFive
+    months.takeRight(5) shouldBe expectedFinalFive
+
+    (1900 to 2100) - months.map(_.year) shouldBe expectedNon5erYears
+  }
+}