2016 Update

Task/Knuths-algorithm-S/Elixir/knuths-algorithm-s.elixir

@@ -0,0 +1,25 @@
+defmodule Knuth do
+  def s_of_n_creator(n), do: {n, 1, []}
+
+  def s_of_n({n, i, ys}, x) do
+    cond do
+      i <= n -> {n, i+1, [x|ys]}
+
+      :rand.uniform(i) <= n ->
+        {n, i+1, List.replace_at(ys, :rand.uniform(n)-1, x)}
+
+      true -> {n, i+1, ys}
+    end
+  end
+end
+
+results = Enum.reduce(1..100000, %{}, fn _, freq ->
+  {_, _, xs} = Enum.reduce(1..10, Knuth.s_of_n_creator(3), fn x, s ->
+    Knuth.s_of_n(s, x)
+  end)
+  Enum.reduce(xs, freq, fn x, freq ->
+    Map.put(freq, x, (freq[x] || 0) + 1)
+  end)
+end)
+
+IO.inspect results