tic-tac-toe.py

# Tic Tac Toe by Raheel Junaid
# Date Finished: July 4th
# Full YouTube Series: https://youtube.com/playlist?list=PL3ZaFz0_yUh4KSXM8qXyPjxr_j5uxcG4E

# This Version is commented

from random import randint

class Game:
    def __init__(self) -> None:
        self.board = [[None for i in range(3)] for i in range(3)] # Generate empty board

    def display_board(self, numbers=None):
        # Determine which (if any) numbers to show
        # Compact two conditionals in one (pep8 column restriction)
        show_numbers_x = True if numbers == 'x' or numbers == 'both' else False
        show_numbers_y = True if numbers == 'y' or numbers == 'both' else False
        
        for row_count, row in enumerate(self.board):
            # Print line seperator for every row
            if row_count != 0:
                print(f'\n   {"-" * 10}')

            for col_count, col in enumerate(row):
                # Show the numbers on the left if requested
                if col_count == 0 and show_numbers_x:
                    print(str(row_count + 1), ' ', end="")
                elif col_count == 0:
                    print('   ', end="")
                    
                # None values are symbolic, reassign to empty space
                col = ' ' if col is None else col
                print(col, end="")

                # Add a divider between the first two columns
                if col_count != 2:
                    print(" | ", end="")

            # The last row should show a new line
            if row_count == 2:
                if show_numbers_y: # Show properly spaced numbers if requested
                    print("\n\n   1   2   3", end="")
                print('\n')
    
    def place_piece(self, piece, x_pos, y_pos):
        self.board[x_pos][y_pos] = piece

# Determine if all elements in a given list are equal
all_equal = lambda iterable: iterable.count(iterable[0]) == len(iterable)

# Return a list of all pieces on the board
def all_pieces(board):
    all_pieces = list()
    for row in range(3):
        for column in range(3):
            all_pieces.append(board[row][column])
    return all_pieces

# Check whether a certain axis (or diagonal) has the same pieces)
def check_win(board):
    # Check for a tie
    if all(all_pieces(game.board)):
        return 'tie'
    # Check all rows
    for row in board:
        if all_equal(row) and all(row):
            return 'win'
    # Check all columns
    for i in range(3):
        column = [board[0][i], board[1][i], board[2][i]]
        if all_equal(column) and all(column):
            return 'win'
    # Check both diagonals
    tl_br = [board[0][0], board[1][1], board[2][2]]
    tr_bl = [board[0][2], board[1][1], board[2][0]]
    for cross in [tl_br, tr_bl]:
        if all_equal(cross) and all(cross):
            return 'win'
    # Return if the game is still playable
    return False

def play(piece):
    print(f"{piece.upper()}'s turn.")

    # O is always computers move
    if piece == 'o':
        move = computerMove(game.board)
        game.place_piece('o', move[0], move[1])
    else:
        # Accept coordinates for piece placement
        game.display_board(numbers='y')
        y_pos = int(input("Choose Y Position: ")) - 1
        game.display_board(numbers='x')
        x_pos = int(input("Choose X Position: ")) - 1

        # Ensure the location isn't already occupied
        if game.board[x_pos][y_pos] == None:
            game.place_piece(piece, x_pos, y_pos)
        else:
            print("A piece is already there, please try again.")
            play(piece)

def computerMove(board):
    # Test whether there could be a winner
    # Check every unoccupied column
    for row_count, row in enumerate(board):
        for col_count, column in enumerate(row):
            if column == None:
                # Toggle between both players to see if someone is going to win
                for piece in ['x', 'o']:
                    board[row_count][col_count] = piece
                    if check_win(board) == 'win':
                        # Place a piece in that position if a winner is possible
                        return row_count, col_count
                    board[row_count][col_count] = None
    # Random Move
    random_move = [randint(0, 2), randint(0, 2)]
    # Check if the random location is occupied
    while board[random_move[0]][random_move[1]] != None:
        random_move = [randint(0,2), randint(0, 2)]
    return random_move

# Main program (very little error-handling)
game = Game()

while True:
    for piece in ['x', 'o']: # Take turns playing the game
        play(piece)
        result = check_win(game.board)
        if result == 'win' or result == 'tie':
            game.display_board()
            # Print line seperator
            print('-' * 20)
            if result == 'win':
                print(piece.upper(), 'WINS!')
            else:
                print('Tie')
            print('-' * 20)
            restart = input('Play again [y/n]? ')
            if restart.lower() == 'n':
                break
            game = Game() # Empty the board