Data commit

Task/Power-set/Elixir/power-set.elixir

@@ -0,0 +1,29 @@
+defmodule RC do
+  use Bitwise
+  def powerset1(list) do
+    n = length(list)
+    max = round(:math.pow(2,n))
+    for i <- 0..max-1, do: (for pos <- 0..n-1, band(i, bsl(1, pos)) != 0, do: Enum.at(list, pos) )
+  end
+
+  def powerset2([]), do: [[]]
+  def powerset2([h|t]) do
+    pt = powerset2(t)
+    (for x <- pt, do: [h|x]) ++ pt
+  end
+
+  def powerset3([]), do: [[]]
+  def powerset3([h|t]) do
+    pt = powerset3(t)
+    powerset3(h, pt, pt)
+  end
+
+  defp powerset3(_, [], acc), do: acc
+  defp powerset3(x, [h|t], acc), do: powerset3(x, t, [[x|h] | acc])
+end
+
+IO.inspect RC.powerset1([1,2,3])
+IO.inspect RC.powerset2([1,2,3])
+IO.inspect RC.powerset3([1,2,3])
+IO.inspect RC.powerset1([])
+IO.inspect RC.powerset1(["one"])