Three players, P1, P2 and P3, are playing a game as described below. In a room, there are three doors, marked with A, B and C. P1 hides behind a door. P2 and P3 do not know P1's choice. Then P2 enters the room. And P2 picks one door and opens it. If P1 is behind the door picked by P2, then the game is over and P2 wins. If P1 is not behind the door opened by P2, then P3 enters the room and opens one of the two remaining doors. If P1 is behind the door picked by P3, then P3 wins. If P1 is not behind the doors opened by P2 and P3, then P1 wins. The winner receives 1 dollar and all others receive zero. (1) Represent the game in a game tree. (2) Write down one example of strategies for P1, P2 and P3.