tictactoe.py

# Tic Tac Toe

TL, TM, TR, ML, MM, MR, BL, BM, BR = 'TL', 'TM', 'TR', 'ML', 'MM', 'MR', 'BL', 'BM', 'BR'
ALL_SPACES = (TL, TM, TR, ML, MM, MR, BL, BM, BR)
X, O, BLANK = 'X', 'O', ' '

def main():
    print('Welcome to Tic Tac Toe!')
    mainBoard = getNewBoard()
    turn = X
    nextTurn = O

    while True:
        print('It is ' + turn + '\'s turn.')
        drawBoard(mainBoard)
        move = getPlayerMove(mainBoard)
        setSpace(mainBoard, move, turn)

        if isWinner(mainBoard, turn):
            drawBoard(mainBoard)
            print(turn + ' has won the game!')
            break
        elif isBoardFull(mainBoard):
            drawBoard(mainBoard)
            print('The game is a tie!')
            break
        print()

        turn, nextTurn = nextTurn, turn

def drawBoard(board):
    # Display a text-representation of the board.
    print(f'{board[TL]}|{board[TM]}|{board[TR]}')
    print('-----')
    print(f'{board[ML]}|{board[MM]}|{board[MR]}')
    print('-----')
    print(f'{board[BL]}|{board[BM]}|{board[BR]}')

def isWinner(board, mark):
    # Return True if mark is a winner on board.
    bo, m = board, mark # These shorter names make the following code shorter.
    return ((bo[TL] == m and bo[TM] == m and bo[TR] == m) or # across the top
            (bo[ML] == m and bo[MM] == m and bo[MR] == m) or # across the middle
            (bo[BL] == m and bo[BM] == m and bo[BR] == m) or # across the bottom
            (bo[TL] == m and bo[ML] == m and bo[BL] == m) or # down the left side
            (bo[TM] == m and bo[MM] == m and bo[BM] == m) or # down the middle
            (bo[TR] == m and bo[MR] == m and bo[BR] == m) or # down the right side
            (bo[TL] == m and bo[MM] == m and bo[BR] == m) or # diagonal
            (bo[TR] == m and bo[MM] == m and bo[BL] == m)) # diagonal

def getPlayerMove(board):
    # Let the player type in their move.
    move = None
    while move not in ALL_SPACES or not board[move] == BLANK:
        print('What is your move? (TL TM TR ML MM MR BL BM BR)')
        move = input().upper()
    return move

def isBoardFull(board):
    # Return True if every space on the board has been taken. Otherwise return False.
    for space in ALL_SPACES:
        if board[space] == BLANK:
            return False
    return True

def getNewBoard():
    # Create a new, blank tic tac toe board.
    board = {}
    for space in ALL_SPACES:
        board[space] = BLANK
    return board

def setSpace(board, space, mark):
    # Sets the space on the board to mark, if it is valid.
    if mark not in (X, O, BLANK):
        raise ValueError('invalid mark for space')
    board[space] = mark

if __name__ == '__main__':
    main()