# 画棋盘的函数，传入一个放置棋子的列表
def drawBoard(board) :
 
 print(" " + board[7] + " | " + board[8] + " | " + board[9])
 print("------------")
 print(" " + board[4] + " | " + board[5] + " | " + board[6])
 print("------------")
 print(" " + board[1] + " | " + board[2] + " | " + board[3])
 
# 玩家选择所想用的棋子种类
def inputPlayerLetter() :
 
 letter = ''
 while not (letter == 'X' or letter == 'O') :
 print("Do you want to be X or O")
 # 自动将小写转化为大写
 letter = input().upper()
 
 # 如果玩家选择的X，则自动将O赋给电脑，反之一样
 if letter == 'X' :
 return ['X','O']
 else :
 return ['O','X']
 
# 这里随机生成0或者1来表示谁先落子
def whoGoesFirst() :
 
 if random.randint(0,1) == 0 :
 return 'computer'
 else :
 return 'player'
 
# 如果玩家选择y或者Y则游戏重新开始
def playAgain():
 
 print("Do you want to play again")
 return input().lower().startswith('y')
 
# 将棋子放置到棋盘上面
# board参数是储存棋子的列表
# letter参数是棋子的类型
# move是选择将棋子放在哪
def makeMove(board, letter, move) :
 
 board[move] = letter
 
# 根据井字棋规则判断是否获胜
def isWinner(bo, le) :
 
 return ((bo[7] == le and bo[8] == le and bo[9] == le) or
  (bo[4] == le and bo[5] == le and bo[6] == le) or
  (bo[1] == le and bo[2] == le and bo[3] == le) or
  (bo[7] == le and bo[4] == le and bo[1] == le) or
  (bo[8] == le and bo[5] == le and bo[2] == le) or
  (bo[9] == le and bo[6] == le and bo[3] == le) or
  (bo[7] == le and bo[5] == le and bo[3] == le) or
  (bo[9] == le and bo[5] == le and bo[1] == le))
 
# 将已经在棋盘上的棋子备份,随时更新
def getBoardCopy(board) :
 
 dupeBoard = []
 for i in board :
 dupeBoard.append(i)
 
 return dupeBoard
 
# 判断棋盘是否还有可落子的地方
def isSpaceFree(board, move) :
 
 return board[move] == ' '
 
# 获取玩家落子的位置
def getPlayerMove(board) :
 
 move = ' '
 # 判断落子的位置是否正确以及棋盘是否还能落子
 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")
 move = input()
 return int(move)
 
# 找到可以落子的地方，主要是计算机使用的
def chooseRandomMoveFromList(board, moveList) :
 
 possibleMoves = []
 for i in moveList :
 if isSpaceFree(board, i) :
  possibleMoves.append(i)
 
 if len(possibleMoves) != 0 :
 return random.choice(possibleMoves)
 else :
 return None

# 电脑落子
def getComputerMove(board, computerLetter) :
 
 # 给出棋盘上电脑和玩家棋子的类型
 if computerLetter == 'X' :
 playerLetter = 'O'
 else :
 playerLetter = 'X'
 
 for i in range(1,10) :
 # 在备份的棋盘中判断是否有可以落子的地方
 copy = getBoardCopy(board)
 if isSpaceFree(copy, i) :
  # 如果有可以落子的地方,则先在备份的棋盘上落子
  makeMove(copy, computerLetter, i)
  # 落子后判断电脑是否能赢,并且返回能赢的落子的位置
  if isWinner(copy, computerLetter) :
  return i
 
 for i in range(1,10) :
 copy = getBoardCopy(board)
 if isSpaceFree(copy, i) :
  # 在备份的棋盘上模拟玩家落子
  makeMove(copy, playerLetter, i)
  # 如果下一次玩家落子就可以赢,返回玩家落子的位置,用于堵住玩家
  if isWinner(copy, playerLetter) :
  return i
 
 # 随机在四个角处落子
 move = chooseRandomMoveFromList(board,[1,3,7,9])
 if move != None :
 return move
 
 # 如果角处已被占满,则落子在中间位置5处
 if isSpaceFree(board, 5) :
 return 5
 
 # 如果角和中间都被占满,则随机选择边上落子
 return chooseRandomMoveFromList(board,[2,4,6,8])
 
# 判断棋盘是否已满
def isBoardFull(board) :
 
 for i in range(1,10) :
 if isSpaceFree(board, i) :
  return False
 return True
 
 
print("Welcome to Tictactoe !!!")
 
while True :
 
 # 初始化棋盘为空
 theBoard = [' '] * 10
 # 玩家和电脑棋子类型的选择
 playerLetter, computerLetter = inputPlayerLetter()
 # 先后顺序的决定
 turn = whoGoesFirst()
 print('The ' + turn + ' will go first')
 # 游戏开始的标志位,当游戏结束时变成False
 gameIsPlaying = True
 
 while gameIsPlaying :
 # 玩家先行
 if turn == 'player' :
  drawBoard(theBoard)
  # 获取玩家下棋的位置
  move = getPlayerMove(theBoard)
  # 将玩家的棋子传入列表相应的位置
  makeMove(theBoard, playerLetter, move)
 
  # 如果玩家获胜,标志位变为False
  if isWinner(theBoard, playerLetter) :
  drawBoard(theBoard)
  print("You win !")
  gameIsPlaying = False
  # 否则则判断棋盘是否已满
  else :
  if isBoardFull(theBoard) :
   drawBoard(theBoard)
   print("Tie")
   break
  # 若棋盘未满,且玩家已落子,则下一次落到计算机落子
  else :
   turn = 'computer'
 # 电脑先行
 else :
  # 电脑随机选择位置落子
  move = getComputerMove(theBoard, computerLetter)
  makeMove(theBoard, computerLetter, move)
 
  # 如果电脑落子获胜,则游戏结束
  if isWinner(theBoard, computerLetter) :
  drawBoard(theBoard)
  print("You lose !")
  gameIsPlaying = False
  else :
  if isBoardFull(theBoard) :
   drawBoard(theBoard)
   print("Tie")
   break
  else :
   turn = 'player'
 
 # 玩家没有再次开始游戏,则跳出循环
 if not playAgain():
 break