2016 Update

Task/Constrained-random-points-on-a-circle/Elixir/constrained-random-points-on-a-circle-1.elixir

@@ -1,17 +1,19 @@
 defmodule Random do
   defp generate_point(0, _, _, set), do: set
-  defp generate_point(n, f, range, set) do
+  defp generate_point(n, f, condition, set) do
     point = {x,y} = {f.(), f.()}
-    if x*x + y*y in range and not Set.member?(set, point),
-      do:   generate_point(n-1, f, range, Set.put(set, point)),
-      else: generate_point(n,   f, range, set)
+    if x*x + y*y in condition and not point in set,
+      do:   generate_point(n-1, f, condition, MapSet.put(set, point)),
+      else: generate_point(n,   f, condition, set)
   end
+
   def circle do
     f = fn -> :rand.uniform(31) - 16 end
-    points = generate_point(100, f, 10*10..15*15, HashSet.new)
-    for x <- -15..15 do
-      for y <- -15..15 do
-        IO.write if Set.member?(points, {x,y}), do: "x", else: " "
+    points = generate_point(100, f, 10*10..15*15, MapSet.new)
+    range = -15..15
+    for x <- range do
+      for y <- range do
+        IO.write if {x,y} in points, do: "x", else: " "
       end
       IO.puts ""
     end

Task/Constrained-random-points-on-a-circle/Elixir/constrained-random-points-on-a-circle-2.elixir

@@ -1,15 +1,12 @@
 defmodule Constrain do
-  defp precalculate(range, condition) do
-    for x <- range, y <- range, x*x + y*y in condition, do: {x,y}
-  end
-
   def circle do
     range = -15..15
-    all_points = precalculate(range, 10*10..15*15)
-    IO.puts length(all_points)
-    points = Enum.shuffle(all_points) |> Enum.take(100)
-    Enum.each(-15..15, fn x ->
-      IO.puts Enum.map(range, fn y -> if Enum.member?(points, {x,y}), do: "o ", else: "  " end)
+    r2 = 10*10..15*15
+    all_points = for x <- range, y <- range, x*x+y*y in r2, do: {x,y}
+    IO.puts "Precalculate: #{length(all_points)}"
+    points = Enum.take_random(all_points, 100)
+    Enum.each(range, fn x ->
+      IO.puts Enum.map(range, fn y -> if {x,y} in points, do: "o ", else: "  " end)
     end)
   end
 end