Data commit

Task/Flipping-bits-game/Elixir/flipping-bits-game.elixir

@@ -0,0 +1,67 @@
+defmodule Flip_game do
+  @az  Enum.map(?a..?z, &List.to_string([&1]))
+  @in2i Enum.concat(Enum.map(1..26, fn i -> {to_string(i), i} end),
+                    Enum.with_index(@az) |> Enum.map(fn {c,i} -> {c,-i-1} end))
+        |> Enum.into(Map.new)
+
+  def play(n) when n>2 do
+    target = generate_target(n)
+    display(n, "Target: ", target)
+    board = starting_config(n, target)
+    play(n, target, board, 1)
+  end
+
+  def play(n, target, board, moves) do
+    display(n, "Board: ", board)
+    ans = IO.gets("row/column to flip: ") |> String.strip |> String.downcase
+    new_board = case @in2i[ans] do
+                  i when i in 1..n   -> flip_row(n, board, i)
+                  i when i in -1..-n -> flip_column(n, board, -i)
+                  _ -> IO.puts "invalid input: #{ans}"
+                       board
+                end
+    if target == new_board do
+      display(n, "Board: ", new_board)
+      IO.puts "You solved the game in #{moves} moves"
+    else
+      IO.puts ""
+      play(n, target, new_board, moves+1)
+    end
+  end
+
+  defp generate_target(n) do
+    for i <- 1..n, j <- 1..n, into: Map.new, do: {{i, j}, :rand.uniform(2)-1}
+  end
+
+  defp starting_config(n, target) do
+    Enum.concat(1..n, -1..-n)
+    |> Enum.take_random(n)
+    |> Enum.reduce(target, fn x,acc ->
+         if x>0, do: flip_row(n, acc, x),
+               else: flip_column(n, acc, -x)
+       end)
+  end
+
+  defp flip_row(n, board, row) do
+    Enum.reduce(1..n, board, fn col,acc ->
+      Map.update!(acc, {row,col}, fn bit -> 1 - bit end)
+    end)
+  end
+
+  defp flip_column(n, board, col) do
+    Enum.reduce(1..n, board, fn row,acc ->
+      Map.update!(acc, {row,col}, fn bit -> 1 - bit end)
+    end)
+  end
+
+  defp display(n, title, board) do
+    IO.puts title
+    IO.puts "   #{Enum.join(Enum.take(@az,n), " ")}"
+    Enum.each(1..n, fn row ->
+      :io.fwrite "~2w ", [row]
+      IO.puts Enum.map_join(1..n, " ", fn col -> board[{row, col}] end)
+    end)
+  end
+end
+
+Flip_game.play(3)