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May 7, 2019 04:12
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a simple game of tic-tac-toe
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| from dataclasses import dataclass | |
| from typing import Tuple | |
| PLAYER_X = 'X' | |
| PLAYER_O = 'O' | |
| EMPTY = ' ' | |
| def other(player): | |
| return PLAYER_O if player == PLAYER_X else PLAYER_X | |
| @dataclass | |
| class GameState: | |
| board: Tuple[str] | |
| to_move: str | |
| MOVES = "A0 B0 C0 A1 B1 C1 A2 B2 C2".split() | |
| def initial_state(): | |
| "The state at the beginning of a game." | |
| return GameState(board=tuple([EMPTY]*9), | |
| to_move=PLAYER_X) | |
| LINES = [ | |
| [0,1,2], | |
| [3,4,5], | |
| [6,7,8], | |
| [0,3,6], | |
| [1,4,7], | |
| [2,5,8], | |
| [0,4,8], | |
| [2,4,6] | |
| ] | |
| def game_over(state): | |
| """Is the game over? | |
| If so, return the winning player. | |
| """ | |
| board = state.board | |
| for x,y,z in LINES: | |
| if board[x] == EMPTY: | |
| continue | |
| elif board[x] == board[y] == board[z]: | |
| return board[x] | |
| return None | |
| def render(state): | |
| "Draw the game board associated with this state." | |
| border = " +---+---+---+" | |
| row = lambda i: "{} | {} | {} | {} |".\ | |
| format(i, *(state.board[3*i:3*(i+1)])) | |
| print(f" A B C") | |
| for i in range(3): | |
| print(border) | |
| print(row(i)) | |
| print(border, "\n") | |
| def prompt_move(state): | |
| "Primpt the current player for a move." | |
| while True: | |
| try: | |
| move = input(f"Please enter a move (Player {state.to_move}): ") | |
| pos = MOVES.index(move.upper()) | |
| if state.board[pos] == EMPTY: | |
| return pos | |
| print("That square is already occupied!") | |
| except ValueError: | |
| print("Valid moves must be from [A-C][0-2].") | |
| def do_move(state, pos): | |
| "Apply a move, returning an updated state." | |
| if state.board[pos] != EMPTY: | |
| raise ValueError(f"Expected an empty square at {pos}, \ | |
| but found {state.board[pos]}") | |
| updated = state.board[:pos] + (state.to_move,) + state.board[pos+1:] | |
| return GameState(board=updated, | |
| to_move=other(state.to_move)) | |
| def play(): | |
| "Play a game from start to finish." | |
| state = initial_state() | |
| while True: | |
| render(state) | |
| pos = prompt_move(state) | |
| state = do_move(state, pos) | |
| winner = game_over(state) | |
| if winner is not None: | |
| render(state) | |
| print(f"Player {winner} is the winner!") | |
| break | |
| if __name__ == "__main__": | |
| play() |
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