#76
Tic-Tac-Toe

  1. """Tic-Tac-Toe, by Al Sweigart [email protected]
  2. The classic board game.
  3. This code is available at https://nostarch.com/big-book-small-python-programming
  4. Tags: short, board game, game, two-player"""
  5. 
  6. ALL_SPACES = ['1', '2', '3', '4', '5', '6', '7', '8', '9']
  7. X, O, BLANK = 'X', 'O', ' '  # Constants for string values.
  8. 
  9. 
 10. def main():
 11.     print('Welcome to Tic-Tac-Toe!')
 12.     gameBoard = getBlankBoard()  # Create a TTT board dictionary.
 13.     currentPlayer, nextPlayer = X, O  # X goes first, O goes next.
 14. 
 15.     while True:  # Main game loop.
 16.         # Display the board on the screen:
 17.         print(getBoardStr(gameBoard))
 18. 
 19.         # Keep asking the player until they enter a number 1-9:
 20.         move = None
 21.         while not isValidSpace(gameBoard, move):
 22.             print('What is {}\'s move? (1-9)'.format(currentPlayer))
 23.             move = input('> ')
 24.         updateBoard(gameBoard, move, currentPlayer)  # Make the move.
 25. 
 26.         # Check if the game is over:
 27.         if isWinner(gameBoard, currentPlayer):  # Check for a winner.
 28.             print(getBoardStr(gameBoard))
 29.             print(currentPlayer + ' has won the game!')
 30.             break
 31.         elif isBoardFull(gameBoard):  # Check for a tie.
 32.             print(getBoardStr(gameBoard))
 33.             print('The game is a tie!')
 34.             break
 35.         # Switch turns to the next player:
 36.         currentPlayer, nextPlayer = nextPlayer, currentPlayer
 37.     print('Thanks for playing!')
 38. 
 39. 
 40. def getBlankBoard():
 41.     """Create a new, blank tic-tac-toe board."""
 42.     # Map of space numbers: 1|2|3
 43.     #                       -+-+-
 44.     #                       4|5|6
 45.     #                       -+-+-
 46.     #                       7|8|9
 47.     # Keys are 1 through 9, the values are X, O, or BLANK:
 48.     board = {}
 49.     for space in ALL_SPACES:
 50.         board[space] = BLANK  # All spaces start as blank.
 51.     return board
 52. 
 53. 
 54. def getBoardStr(board):
 55.     """Return a text-representation of the board."""
 56.     return '''
 57.       {}|{}|{}  1 2 3
 58.       -+-+-
 59.       {}|{}|{}  4 5 6
 60.       -+-+-
 61.       {}|{}|{}  7 8 9'''.format(board['1'], board['2'], board['3'],
 62.                                 board['4'], board['5'], board['6'],
 63.                                 board['7'], board['8'], board['9'])
 64. 
 65. def isValidSpace(board, space):
 66.     """Returns True if the space on the board is a valid space number
 67.     and the space is blank."""
 68.     return space in ALL_SPACES and board[space] == BLANK
 69. 
 70. 
 71. def isWinner(board, player):
 72.     """Return True if player is a winner on this TTTBoard."""
 73.     # Shorter variable names used here for readablility:
 74.     b, p = board, player
 75.     # Check for 3 marks across 3 rows, 3 columns, and 2 diagonals.
 76.     return ((b['1'] == b['2'] == b['3'] == p) or  # Across top
 77.             (b['4'] == b['5'] == b['6'] == p) or  # Across middle
 78.             (b['7'] == b['8'] == b['9'] == p) or  # Across bottom
 79.             (b['1'] == b['4'] == b['7'] == p) or  # Down left
 80.             (b['2'] == b['5'] == b['8'] == p) or  # Down middle
 81.             (b['3'] == b['6'] == b['9'] == p) or  # Down right
 82.             (b['3'] == b['5'] == b['7'] == p) or  # Diagonal
 83.             (b['1'] == b['5'] == b['9'] == p))    # Diagonal
 84. 
 85. def isBoardFull(board):
 86.     """Return True if every space on the board has been taken."""
 87.     for space in ALL_SPACES:
 88.         if board[space] == BLANK:
 89.             return False  # If any space is blank, return False.
 90.     return True  # No spaces are blank, so return True.
 91. 
 92. 
 93. def updateBoard(board, space, mark):
 94.     """Sets the space on the board to mark."""
 95.     board[space] = mark
 96. 
 97. 
 98. if __name__ == '__main__':
 99.     main()  # Call main() if this module is run, but not when imported.