I wrote a mediocre Tic Tac Toe game. Take a look.
# Tic-Tac-Toe
# Plays the game of tic-tac-toe against a human opponent
# global constants
X = "X"
O = "O"
EMPTY = " "
TIE = "TIE"
NUM_SQUARES = 9
def display_instruct():
"""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():
"""Determine if 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.")
computer = X
human = O
return computer, human
def new_board():
"""Create new game board."""
board = []
for square in range(NUM_SQUARES):
board.append(EMPTY)
return board
def display_board(board):
"""Display game board on screen."""
print("\n\t", board[0], "|", board[1], "|", board[2])
print("\t", "---------")
print("\t", board[3], "|", board[4], "|", board[5])
print("\t", "---------")
print("\t", board[6], "|", board[7], "|", board[8], "\n")
def legal_moves(board):
"""Create list of legal moves."""
moves = []
for square in range(NUM_SQUARES):
if board[square] == EMPTY:
moves.append(square)
return moves
def winner(board):
"""Determine 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 = (0, 7, 6, 3, 8, 1, 4, 5, 2)
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, undo 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, undo it
board[move] = EMPTY
# since no one can win on next move, pick best open square
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 congrat_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_instruct()
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)
the_winner = winner(board)
congrat_winner(the_winner, computer, human)
# start the program
main()
input("\n\nPress the enter key to quit.")
BEST_MOVESpresumably to make an unbeatable opponent, as one of the 'challenges' the book provides is to do this (I was doing this task myself and became a bit unsure by the challenge). This might be why there is a lot of repetition in the coding, as the book structures its chapters in a different way to the 'most efficient route' possible from the start. \$\endgroup\$