Initial data commit

Task/N-queens-problem/Elixir/n-queens-problem.elixir

@@ -0,0 +1,38 @@
+defmodule RC do
+  def queen(n, display \\ true) do
+    solve(n, [], [], [], display)
+  end
+
+  defp solve(n, row, _, _, display) when n==length(row) do
+    if display, do: print(n,row)
+    1
+  end
+  defp solve(n, row, add_list, sub_list, display) do
+    Enum.map(Enum.to_list(0..n-1) -- row, fn x ->
+      add = x + length(row)             # \ diagonal check
+      sub = x - length(row)             # / diagonal check
+      if (add in add_list) or (sub in sub_list) do
+        0
+      else
+        solve(n, [x|row], [add | add_list], [sub | sub_list], display)
+      end
+    end) |> Enum.sum                    # total of the solution
+  end
+
+  defp print(n, row) do
+    IO.puts frame = "+" <> String.duplicate("-", 2*n+1) <> "+"
+    Enum.each(row, fn x ->
+      line = Enum.map_join(0..n-1, fn i -> if x==i, do: "Q ", else: ". " end)
+      IO.puts "| #{line}|"
+    end)
+    IO.puts frame
+  end
+end
+
+Enum.each(1..6, fn n ->
+  IO.puts " #{n} Queen : #{RC.queen(n)}"
+end)
+
+Enum.each(7..12, fn n ->
+  IO.puts " #{n} Queen : #{RC.queen(n, false)}"             # no display
+end)