#Tic-Tac-Toe 井字棋游戲
#全局常量
X="X"
O="O"
EMPTY=" "
#詢問(wèn)是否繼續(xù)
def ask_yes_no(question):
 response=None;
 while response not in("y","n"):
  response=input(question).lower()
 return response
#輸入位置數(shù)字
def ask_number(question ,low,high):
 response=None
 while response not in range(low,high):
  response=int(input(question))
 return response
#詢問(wèn)誰(shuí)先走，先走方為X,后走方為O
#函數(shù)返回計(jì)算機(jī)方，玩家的角色代號(hào)
def pieces():
 go_first=ask_yes_no("玩家你是否先走（y/n):")
 if go_first=="y":
  print("\n玩家你先走.")
  human=X
  computer=O
 else:
  print("\n計(jì)算機(jī)先走.")
  computer=X
  human=O
 return computer,human
#產(chǎn)生新的棋盤
def new_board():
 board=[]
 for square in range(9):
  board.append(EMPTY)
 return board
#顯示棋盤
def display_board(board):
 board2=board[:]
 for i in range(len(board)):
  if board[i]==EMPTY:
   board2[i]=i
 print("\t",board2[0],"|",board2[1],"|",board2[2])
 print("\t","----------")
 print("\t",board2[3],"|",board2[4],"|",board2[5])
 print("\t", "----------")
 print("\t",board2[6],"|",board2[7],"|",board2[8],"\n")
 #產(chǎn)生可以合法走棋位置序列（也就是還未下過(guò)子位置）
def legal_moves(board):
 moves=[]
 for square in range(9):
  if board[square]==EMPTY:
   moves.append(square)
 return moves
 #判斷輸贏
def winner(board):
  # 所有贏得可能情況，例如（0,1,2）就是第一行，（0,4,8,），（2,4,6）就是對(duì)角線
 WAYS_TO_WIN=((0,1,2,),(3,4,5),(6,7,8),(0,3,6),(1,4,7),(2,5,8),(0,4,8),(2,4,6))
 for row in WAYS_TO_WIN:
  if board[row[0]]==board[row[1]]==board[row[2]]!=EMPTY:
   winner=board[row[0]]
   return winner
   #棋盤沒(méi)有空位置
 if EMPTY not in board:
  return "TIE"
 return False
  #人走棋
def human_move (board,human):
 legal =legal_moves(board)
 move =None
 while move not in legal:
  move=ask_number("你走那個(gè)位置？（0-8）：",0,9)
  if move not in legal:
   print("\n此位置已經(jīng)落過(guò)子了")
     #print("Fine...")
 return move
  #計(jì)算機(jī)走棋
def computer_move(board,computer ,human):
 board=board[:]
   #按優(yōu)劣順序排序的下棋走子
 BEST_MOVES=(4,0,2,6,8,1,3,5,7) #最佳下棋位置順序表
   #如果計(jì)算機(jī)能贏，就走那個(gè)位置
 for move in legal_moves(board):
   board[move]=computer
   if winner(board)==computer:
    print("計(jì)算機(jī)下棋位置...",move)
    return move
    #取消走棋方案
   board[move]=EMPTY
   #如果玩家能贏就堵住那個(gè)位置
 for move in legal_moves(board):
   board[move]=human
   if winner(board)==human:
    print("計(jì)算機(jī)下棋位置...",move)
    return move
    #取消走棋方案
   board[move]=EMPTY
   #如果不是上面情況，也就是這一輪贏不了
   #則是從最佳下棋位置表中挑出第一個(gè)合法位置
 for move in BEST_MOVES:
  if move in legal_moves(board):
   print("計(jì)算機(jī)下棋位置....",move)
   return move
  #轉(zhuǎn)換角色
def next_turn(turn):
 if turn ==X:
   return O
 else:
  return X
  #主函數(shù)
def main():
  computer,human=pieces()
  turn =X
  board=new_board()
  display_board(board)
  while not winner(board):
   if turn ==human:
    move=human_move(board,human)
    board[move]=human
   else:
    move=computer_move(board,computer,human)
    board[move]=computer
   display_board(board)
   turn=next_turn(turn) #轉(zhuǎn)換角色
     #游戲結(jié)束輸出輸贏或和棋信息
  the_winner=winner(board)
  if the_winner==computer:
   print("計(jì)算機(jī)贏！\n")
  elif the_winner==human:
   print("玩家贏！\n")
  elif the_winner=="TIE":
   print("平局，游戲結(jié)束\n")

main()
input("按任意鍵退出游戲")