Another update from ingydotnet^djgoku

Task/Dinesmans-multiple-dwelling-problem/Elixir/dinesmans-multiple-dwelling-problem.elixir

@@ -0,0 +1,27 @@
+defmodule Dinesman do
+  def problem do
+    names = ~w( Baker Cooper Fletcher Miller Smith )a
+    predicates = [fn(c)-> :Baker != List.last(c) end,
+                  fn(c)-> :Cooper != List.first(c) end,
+                  fn(c)-> :Fletcher != List.first(c) && :Fletcher != List.last(c) end,
+                  fn(c)-> floor(c, :Miller) > floor(c, :Cooper) end,
+                  fn(c)-> abs(floor(c, :Smith) - floor(c, :Fletcher)) != 1 end,
+                  fn(c)-> abs(floor(c, :Cooper) - floor(c, :Fletcher)) != 1 end]
+
+    permutation(names)
+    |> Enum.filter(fn candidate ->
+         Enum.all?(predicates, fn predicate -> predicate.(candidate) end)
+       end)
+    |> Enum.each(fn name_list ->
+         Enum.with_index(name_list)
+         |> Enum.each(fn {name,i} -> IO.puts "#{name} lives on #{i+1}" end)
+       end)
+  end
+
+  defp floor(c, name), do: Enum.find_index(c, fn x -> x == name end)
+
+  defp permutation([]), do: [[]]
+  defp permutation(list), do: (for x <- list, y <- permutation(list -- [x]), do: [x|y])
+end
+
+Dinesman.problem