RetroCityWeb/tic tac toe.ipynb

# 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 list 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 their 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'

  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 their 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 != 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





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