Lucky38i TTT Game | Python Fiddle

#Tic-Tac-Toe
#Plays the game of Tic-Tac-Toe against a human player

#Global constants
X = 'X'
O = 'O'
EMPTY = ' '
TIE = 'TIE'
NUM_SQUARES = 9

def display_instruction():
	'''Display Game instructions'''
	print ('''

Welcome to the greatest intellectual challenge of all time: Tic-Tac-Toe.
	This will be a showdown between your human brain and my silicon processor.

You will make your move known by entering a number, 0 - 8. The number
	will correspond to the board position as illustrated:

0  |  1  |  2
								 - - - - - - - 
								 3  |  4  |  5
								 - - - - - - - 
								 6  |  7  |  8
	Prepare yourself, human. The ultimate battle is about to begin. \n
	'''
	)

def ask_yes_no(question):
	'''ask a yes or no question.'''
	response = None
	while response not in ('y','n'):
		response = input(question).lower()
	return response

def ask_number(question,low,high):
	'''Ask for a number within a range.'''
	response = None
	while response not in range (low,high):
		response = int(input(question))
	return response

def pieces():
	'''Determines if a player or computer goes first'''
	go_first = ask_yes_no('Do you require the first move? (y,n): ')
	if go_first == 'y':
		print('\nThen take the first move. You will need it.')
		human = X
		computer = O
	else:
		print ('\nYour bravery will be your undoing. I will go first')
		human = O
		computer = X
	return computer,human

def new_board():
	'''Create new game board'''
	board = []
	for square in range(NUM_SQUARES):
		board.append(EMPTY)
	return board

def legal_moves(board):
	'''Creates a legal list of moves'''
	moves = []
	for square in range(NUM_SQUARES):
		if board[square] == EMPTY:
			moves.append(square)

def winner(board):
	'''determines the game winner'''
	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
		if EMPTY not in board:
			return TIE
		return None
def human_move(board,human):
	'''Get human move'''
	legal = legal_moves(board)
	move = None
	while move not in legal:
		move = ask_number('Where will you move? (0-8): ',0, NUM_SQUARES)
		if move not in legal:
			print ('\nThat square is already occupied, foolish human. Choose another.\n')
	print('Fine...')
	return move

def computer_move(board,computer,human):
	'''Make computer move'''
	# Make a copy to work with since function will be changing list 
	board = board [:]

#The best positions to have in order
	BEST_MOVES = (4,0,2,6,8,1,3,5,7)

print ('I shall take square number', end = ' ')
	
	#If computer can win, take that move
	for move in legal_moves(board):
		board[move] = computer
		if winner(board) == computer:
			print (move)
			return move
		#Done checking this move, return it
		board[move] = EMPTY

#if human can win, block that move
	for move in legal_moves(board):
		board[move] = human 
		if winner(board) == human:
			print (move)
			return move
		#Done checking this move, return it
		board[move] = EMPTY
	#Since no square is open, take next best move 
	for move in BEST_MOVES:
		if move in legal_moves(board):
			print(move)
			return move

def next_turn(turn):
	'''switch turns'''
	if turn == X:
		return O
	else:
		return X

def congrats_winner(the_winner, computer, human):
	'''Congratulate the winner'''
	if the_winner != TIE:
		print (the_winner, 'Won!\n')
	else:
		print ('It\'s a tie!\n')

if the_winner == computer:
		print('As I predicted, human, I am triumphant once more.  \n' \
			  'Proof that computers are superior to humans in all regards.')
	elif the_winner == human:
		print ('No, no! It cannot be! somehow you tricked me, human.  \n'\
			   'But never again! I, the computer, so swear it!')
	elif the_winner == TIE:
		print ('You were most lucky, human, and somehow managed to tie me. \n'\
			   'Celebrate today... for this is the best you will ever achieve.')

def main():
	display_instruction()
	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)
		congrats_winner(the_winner,computer, human)

#Start the program
main()
input('\nPress enter to exit')

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