gistfile1.hrl

%3 Write a board that takes a tic-tac-toe board presented as a list or tuple
%  Return the current state of the game (winner, no winner yet, tie, incomplete)

tictactoe(Board) ->
  [S11, S12, S13,
  S21, S22, S23,
  S31, S32, S33] = Board,
  
  Rows = [[S11, S12, S13], [S21, S22, S23], [S31, S32, S33]],
  Cols = [[S11, S21, S31], [S12, S22, S32], [S13, S23, S33]],
  Diag = [[S11, S22, S33], [S13, S22, S31]],
  
  Lines = lists:append([Rows, Cols, Diag]),
  
  %look for winners
  HasWinner = fun(Line) ->
    case same(Line) of
      {true, x} -> io:format("Winner is X~n"), true; %print and return true
      {true, o} -> io:format("Winner is O~n"), true;
      {_, _} -> nil, false
    end
  end,
  
  Winners = lists:dropwhile(fun(Line) -> HasWinner(Line) == false end, Lines),
  case Winners of
    [] ->       
      %look for space to play
      case lists:any(fun(S) -> e == S end, lists:flatten(Lines)) of
        true -> io:format("No Winner~n");
        false -> io:format("Tie~n")
      end;
    _ -> done
  end.
  
%check if all vals are the same and return true or false
%as well as the first val in that list    
same(List) ->
  First = lists:nth(1, List),
  {lists:all(fun(X) -> First == X end, List), First}.


%tic-tac-toe driver function
tt1() ->
  B = [x, x, o,
       o, o, e,
       x, o, x],
  tictactoe(B).