tic_tac_toe.py

#! -*- encoding: utf-8 -*-

# Author: @Mushr00m_Dev

# #############################################
# #              TIC - TAC - TOE              #
# #############################################
import random


def drawBoard(board):
    # This function prints out the board that it was passed.
    # "board" is a list of 10 strings representing the board (ignore index 0)
    print('   |   |')
    print(' ' + board[7] + ' | ' + board[8] + ' | ' + board[9])
    print('   |   |')
    print('-----------')
    print('   |   |')
    print(' ' + board[4] + ' | ' + board[5] + ' | ' + board[6])
    print('   |   |')
    print('-----------')
    print('   |   |')
    print(' ' + board[1] + ' | ' + board[2] + ' | ' + board[3])
    print('   |   |')


def inputPlayerLetter():
    # Lets the player type which letter they want to be.
    # Returns a list with the player's letter as the first item,
    # and the computer's letter as the second.
    letter = ''
    while not (letter == 'X' or letter == 'O'):
        print('Do you want to be X or O?')
        letter = input().upper()
    # the first element in the tuple is the player's letter,
    # the second is the computer's letter.
    if letter == 'X':
        return ['X', 'O']
    else:
        return ['O', 'X']


def whoGoesFirst():
    # Randomly choose the player who goes first.
    if random.randint(0, 1) == 0:
        return 'computer'
    else:
        return 'player'


def playAgain():
    # This function returns True if the player wants
    # to play again, otherwise it returns False.
    print('Do you want to play again? (yes or no)')
    return input().lower().startswith('y')


def makeMove(board, letter, move):
    board[move] = letter


def isWinner(bo, le):
    # Given a board and a player's letter,
    # this function returns True if that player has won.
    # We use bo instead of board and le instead of
    # letter so we don't have to type as much.
    return ((bo[7] == le and bo[8] == le and bo[9] == le) or # across the top
    (bo[4] == le and bo[5] == le and bo[6] == le) or # across the middle
    (bo[1] == le and bo[2] == le and bo[3] == le) or # across the bottom
    (bo[7] == le and bo[4] == le and bo[1] == le) or # down the left side
    (bo[8] == le and bo[5] == le and bo[2] == le) or # down the middle
    (bo[9] == le and bo[6] == le and bo[3] == le) or # down the right side
    (bo[7] == le and bo[5] == le and bo[3] == le) or # diagonal
    (bo[9] == le and bo[5] == le and bo[1] == le)) # diagonal


def getBoardCopy(board):
    # Make a duplicate of the board list and return it the duplicate.
    dupeBoard = []
    for i in board:
        dupeBoard.append(i)
    return dupeBoard


def isSpaceFree(board, move):
    # Return true if the passed move is free on the passed board.
    return board[move] == ' '


def getPlayerMove(board):
    # Let the player type in his move.
    move = ' '
    while move not in '1 2 3 4 5 6 7 8 9'.split() or not isSpaceFree(board, int(move)):
        print('What is your next move? (1-9)')
        move = input()
    return int(move)


def chooseRandomMoveFromList(board, movesList):
    # Returns a valid move from the passed list on the passed board.
    # Returns None if there is no valid move.
    possibleMoves = []
    for i in movesList:
        if isSpaceFree(board, i):
            possibleMoves.append(i)
    if len(possibleMoves) != 0:
        return random.choice(possibleMoves)
    else:
        return None


def getComputerMove(board, computerLetter):
    # Given a board and the computer's letter,
    # determine where to move and return that move.
    if computerLetter == 'X':
        playerLetter = 'O'
    else:
        playerLetter = 'X'
    # Here is our algorithm for our Tic Tac Toe AI:
    # First, check if we can win in the next move
    for i in range(1, 10):
        copy = getBoardCopy(board)
        if isSpaceFree(copy, i):
            makeMove(copy, computerLetter, i)
            if isWinner(copy, computerLetter):
                return i
    # Check if the player could win on his next move, and block them.
    for i in range(1, 10):
        copy = getBoardCopy(board)
        if isSpaceFree(copy, i):
            makeMove(copy, playerLetter, i)
            if isWinner(copy, playerLetter):
                return i
    # Try to take one of the corners, if they are free.
    move = chooseRandomMoveFromList(board, [1, 3, 7, 9])
    if move is not None:
        return move
    # Try to take the center, if it is free.
    if isSpaceFree(board, 5):
        return 5

    # Move on one of the sides.
    return chooseRandomMoveFromList(board, [2, 4, 6, 8])


def isBoardFull(board):
    # Return True if every space on the board
    # has been taken. Otherwise return False.
    for i in range(1, 10):
        if isSpaceFree(board, i):
            return False
    return True


# #############################################
# #                 START                     #
# #############################################
if __name__ == '__main__':
    print('Welcome to Tic Tac Toe!')
    while True:
        # Reset the board
        theBoard = [' '] * 10
        playerLetter, computerLetter = inputPlayerLetter()
        turn = whoGoesFirst()
        print('The ' + turn + ' will go first.')
        gameIsPlaying = True
        while gameIsPlaying:
            if turn == 'player':
                # Player's turn.
                drawBoard(theBoard)
                move = getPlayerMove(theBoard)
                makeMove(theBoard, playerLetter, move)
                if isWinner(theBoard, playerLetter):
                    drawBoard(theBoard)
                    print('Hooray! You have won the game!')
                    gameIsPlaying = False
                else:
                    if isBoardFull(theBoard):
                        drawBoard(theBoard)
                        print('The game is a tie!')
                        break
                    else:
                        turn = 'computer'
            else:
                # Computer's turn.
                move = getComputerMove(theBoard, computerLetter)
                makeMove(theBoard, computerLetter, move)
                if isWinner(theBoard, computerLetter):
                    drawBoard(theBoard)
                    print('The computer has beaten you! You lose.')
                    gameIsPlaying = False
                else:
                    if isBoardFull(theBoard):
                        drawBoard(theBoard)
                        print('The game is a tie!')
                        break
                    else:
                        turn = 'player'
        if not playAgain():
            break