Simple Python Code
# --- Global Constants ---
HUMAN = -1
COMPUTER = 1
EMPTY = 0
def display_board(board):
#Prints the current Tic-Tac-Toe board.
print("\nCurrent Board:")
for i in range(9):
# Add a newline before rows 2 and 3
if i > 0 and i % 3 == 0:
print()
# Print horizontal separators
print("-" * 11)
cell = board[i]
symbol = " "
if cell == HUMAN:
symbol = "X"
elif cell == COMPUTER:
symbol = "O"
# Print cell content with padding
print(f" {symbol} ", end="")
# Print vertical separator between columns
if (i + 1) % 3 != 0:
print("|", end="")
print("\n")
def player_x_turn(board):
#Handles the human player's move (X). Validates input.
while True:
try:
position = int(input("Enter your move (1-9): "))
index = position - 1
if position < 1 or position > 9:
print("Please enter a number between 1 and 9.")
continue
if board[index] != EMPTY:
print("Cell already taken. Try another.")
continue
board[index] = HUMAN
break
except ValueError:
print("Invalid input. Please enter a number between 1 and 9.")
def check_winner(board):
"""Checks for a winner.
Returns:
1 if Computer (O) wins
-1 if Human (X) wins
0 if no winner yet (or draw)
"""
wins = [
[0, 1, 2], [3, 4, 5], [6, 7, 8], # Rows
[0, 3, 6], [1, 4, 7], [2, 5, 8], # Columns
[0, 4, 8], [2, 4, 6] # Diagonals
]
for combo in wins:
a, b, c = combo
if board[a] != EMPTY and board[a] == board[b] == board[c]:
return board[a]
return 0
def minimax(board, player):
"""
The recursive Minimax algorithm.
It searches the entire game tree from the current state to find the best
possible terminal outcome.
Returns the score from the perspective of the current 'player'.
Win = 1, Loss = -1, Draw = 0.
"""
winner = check_winner(board)
if winner != 0:
# If game is over, return value relative to current player.
# If winner matches player, return 1. If opposite, return -1.
return winner * player
if EMPTY not in board:
return 0 # Draw
# Initialize best score lower than lowest possible score (-1)
best_score = -2
for i in range(9):
if board[i] == EMPTY:
# Make temporary move
board[i] = player
# Call minimax for the opponent and negate their score
score = -minimax(board, -player)
# Undo move (backtracking)
board[i] = EMPTY
if score > best_score:
best_score = score
return best_score
def computer_turn(board):
#Computer (O) finds and makes the best move using minimax.
print("Computer is thinking...")
best_score = -2
best_move = -1
for i in range(9):
if board[i] == EMPTY:
# Try a move
board[i] = COMPUTER
# Calculate value of this move; we want to minimize score
score = -minimax(board, HUMAN)
# Undo the move
board[i] = EMPTY
if score > best_score:
best_score = score
best_move = i
# Make the best move found
if best_move != -1:
board[best_move] = COMPUTER
def main():
#Main game loop to handle setup, turns, and game end conditions.
print("=== Tic-Tac-Toe Game ===\n")
print("You are X. Computer is O.")
print("The board positions are numbered 1-9 like a keypad.\n")
while True:
try:
player_order = int(input("Do you want to play 1st or 2nd? (1/2): "))
if player_order not in [1, 2]:
print("Please enter 1 or 2.")
continue
break
except ValueError:
print("Invalid input. Please enter 1 or 2.")
board = [EMPTY] * 9
game_over = False
# Max 9 turns in a game
for turn in range(9):
# Determine whose turn it is based on player order choice
# If player chose 1st: Human plays on even turns (0, 2, 4...)
# If player chose 2nd: Computer plays on even turns
if (turn + player_order) % 2 == 0:
computer_turn(board)
else:
display_board(board)
player_x_turn(board)
# Check game end conditions immediately after a move
winner = check_winner(board)
if winner != 0 or EMPTY not in board:
game_over = True
break
# Final board display and result message
display_board(board)
winner = check_winner(board)
if winner == 0:
print("It's a Draw! A perfect game played by both sides.")
elif winner == HUMAN:
# This should technically never happen if minimax works correctly
print("Congratulations! You (X) win!")
else:
print("Computer (O) wins!")
if __name__ == "__main__":
# This block ensures the main function runs only when executed directly
main()Advanced Python Code
HUMAN = -1
COMPUTER = 1
EMPTY = 0
def display_board(board):
#Prints the current Tic-Tac-Toe board.
print("\nCurrent Board:")
for i in range(9):
if i > 0 and i % 3 == 0:
print()
print("-" * 11)
cell = board[i]
symbol = " "
if cell == HUMAN:
symbol = "X"
elif cell == COMPUTER:
symbol = "O"
print(f" {symbol} ", end="")
if (i + 1) % 3 != 0:
print("|", end="")
print("\n")
def player_x_turn(board):
#Handles the human player's move (X). Validates input.
while True:
try:
position = int(input("Enter your move (1-9): "))
index = position - 1
if position < 1 or position > 9:
print("Please enter a number between 1 and 9.")
continue
if board[index] != EMPTY:
print("Cell already taken. Try another.")
continue
board[index] = HUMAN
break
except ValueError:
print("Invalid input. Please enter a number between 1 and 9.")
def check_winner(board):
#Checks for a winner. 1 - Computer (O) wins -1 if Human (X) wins, 0 if no winner yet (or draw)
wins = [
[0, 1, 2], [3, 4, 5], [6, 7, 8], # Rows
[0, 3, 6], [1, 4, 7], [2, 5, 8], # Columns
[0, 4, 8], [2, 4, 6] # Diagonals
]
for combo in wins:
a, b, c = combo
if board[a] != EMPTY and board[a] == board[b] == board[c]:
return board[a]
return 0
def minimax(board, player):
#The recursive Minimax algorithm.
winner = check_winner(board)
if winner != 0:
return winner * player
if EMPTY not in board:
return 0 # Draw
best_score = -2
for i in range(9):
if board[i] == EMPTY:
board[i] = player
score = -minimax(board, -player)
board[i] = EMPTY
if score > best_score:
best_score = score
return best_score
def computer_turn(board):
#Computer (O) finds and makes the best move using minimax.
print("Computer is thinking...")
best_score = -2
best_move = -1
for i in range(9):
if board[i] == EMPTY:
board[i] = COMPUTER
score = -minimax(board, HUMAN)
board[i] = EMPTY
if score > best_score:
best_score = score
best_move = i
if best_move != -1:
board[best_move] = COMPUTER
def main():
print("=== Tic-Tac-Toe Game ===\n")
print("You are X. Computer is O.")
print("The board positions are numbered 1-9 like a keypad.\n")
while True:
try:
player_order = int(input("Do you want to play 1st or 2nd? (1/2): "))
if player_order not in [1, 2]:
print("Please enter 1 or 2.")
continue
break
except ValueError:
print("Invalid input. Please enter 1 or 2.")
board = [EMPTY] * 9
game_over = False
# Max 9 turns in a game
for turn in range(9):
if (turn + player_order) % 2 == 0:
computer_turn(board)
else:
display_board(board)
player_x_turn(board)
# Check game end conditions immediately after a move
winner = check_winner(board)
if winner != 0 or EMPTY not in board:
game_over = True
break
# Final board display and result message
display_board(board)
winner = check_winner(board)
if winner == 0:
print("It's a Draw! A perfect game played by both sides.")
elif winner == HUMAN:
print("Congratulations! You (X) win!")
else:
print("Computer (O) wins!")
if __name__ == "__main__":
main()Infographics
