# Tic Tac Toe Game Project using Python

Tic tac toe is a very popular game and we are going to implement the tic tac toe game using Python programming. Let us examine some of the rules of the game:-

1. Play occurs on a 3 by 3 grid of 9 squares.
2. Two players take turns marking empty squares, the first marking X’s, the second O’s.
3. A row is any three squares on the grid, adjacent diagonally, vertically or horizontally.
4. If one player places three of the same marks in a row, the player wins.
5. If the spaces are all filled and there is no winner, the game ends in a draw.

To begin the implementation in Python, make sure you have the following tutorials covered:-

Since the game will be you vs the computer, the computer will be using the random function in Python to get the next move.

## Code for Tic Tac Toe Game Project using Python

# Tic Tac Toe

import random

def drawBoard(board):
# This function prints out the board that it was passed.

# "board" is a list of 10 strings representing the board (ignore index 0)
print('   |   |')
print(' ' + board[7] + ' | ' + board[8] + ' | ' + board[9])
print('   |   |')
print('-----------')
print('   |   |')
print(' ' + board[4] + ' | ' + board[5] + ' | ' + board[6])
print('   |   |')
print('-----------')
print('   |   |')
print(' ' + board[1] + ' | ' + board[2] + ' | ' + board[3])
print('   |   |')

def inputPlayerLetter():
# Lets the player type which letter they want to be.
# Returns a list with the player's letter as the first item, and the computer's letter as the second.
letter = ''
while not (letter == 'X' or letter == 'O'):
print('Do you want to be X or O?')
letter = input().upper()

# the first element in the tuple is the player's letter, the second is the computer's letter.
if letter == 'X':
return ['X', 'O']
else:
return ['O', 'X']

def whoGoesFirst():
# Randomly choose the player who goes first.
if random.randint(0, 1) == 0:
return 'computer'
else:
return 'player'

def playAgain():
# This function returns True if the player wants to play again, otherwise it returns False.
print('Do you want to play again? (yes or no)')
return input().lower().startswith('y')

def makeMove(board, letter, move):
board[move] = letter

def isWinner(bo, le):
# Given a board and a player's letter, this function returns True if that player has won.
# We use bo instead of board and le instead of letter so we don't have to type as much.
return ((bo[7] == le and bo[8] == le and bo[9] == le) or # across the top
(bo[4] == le and bo[5] == le and bo[6] == le) or # across the middle
(bo[1] == le and bo[2] == le and bo[3] == le) or # across the bottom
(bo[7] == le and bo[4] == le and bo[1] == le) or # down the left side
(bo[8] == le and bo[5] == le and bo[2] == le) or # down the middle
(bo[9] == le and bo[6] == le and bo[3] == le) or # down the right side
(bo[7] == le and bo[5] == le and bo[3] == le) or # diagonal
(bo[9] == le and bo[5] == le and bo[1] == le)) # diagonal

def getBoardCopy(board):
# Make a duplicate of the board list and return it the duplicate.
dupeBoard = []

for i in board:
dupeBoard.append(i)

return dupeBoard

def isSpaceFree(board, move):
# Return true if the passed move is free on the passed board.
return board[move] == ' '

def getPlayerMove(board):
# Let the player type in his move.
move = ' '
while move not in '1 2 3 4 5 6 7 8 9'.split() or not isSpaceFree(board, int(move)):
print('What is your next move? (1-9)')
move = input()
return int(move)

def chooseRandomMoveFromList(board, movesList):
# Returns a valid move from the passed list on the passed board.
# Returns None if there is no valid move.
possibleMoves = []
for i in movesList:
if isSpaceFree(board, i):
possibleMoves.append(i)

if len(possibleMoves) != 0:
return random.choice(possibleMoves)
else:
return None

def getComputerMove(board, computerLetter):
# Given a board and the computer's letter, determine where to move and return that move.
if computerLetter == 'X':
playerLetter = 'O'
else:
playerLetter = 'X'

# Here is our algorithm for our Tic Tac Toe AI:
# First, check if we can win in the next move
for i in range(1, 10):
copy = getBoardCopy(board)
if isSpaceFree(copy, i):
makeMove(copy, computerLetter, i)
if isWinner(copy, computerLetter):
return i

# Check if the player could win on his next move, and block them.
for i in range(1, 10):
copy = getBoardCopy(board)
if isSpaceFree(copy, i):
makeMove(copy, playerLetter, i)
if isWinner(copy, playerLetter):
return i

# Try to take one of the corners, if they are free.
move = chooseRandomMoveFromList(board, [1, 3, 7, 9])
if move != None:
return move

# Try to take the center, if it is free.
if isSpaceFree(board, 5):
return 5

# Move on one of the sides.
return chooseRandomMoveFromList(board, [2, 4, 6, 8])

def isBoardFull(board):
# Return True if every space on the board has been taken. Otherwise return False.
for i in range(1, 10):
if isSpaceFree(board, i):
return False
return True

print('Welcome to Tic Tac Toe!')

while True:
# Reset the board
theBoard = [' '] * 10
playerLetter, computerLetter = inputPlayerLetter()
turn = whoGoesFirst()
print('The ' + turn + ' will go first.')
gameIsPlaying = True

while gameIsPlaying:
if turn == 'player':
# Player's turn.
drawBoard(theBoard)
move = getPlayerMove(theBoard)
makeMove(theBoard, playerLetter, move)

if isWinner(theBoard, playerLetter):
drawBoard(theBoard)
print('Hooray! You have won the game!')
gameIsPlaying = False
else:
if isBoardFull(theBoard):
drawBoard(theBoard)
print('The game is a tie!')
break
else:
turn = 'computer'

else:
# Computer's turn.
move = getComputerMove(theBoard, computerLetter)
makeMove(theBoard, computerLetter, move)

if isWinner(theBoard, computerLetter):
drawBoard(theBoard)
print('The computer has beaten you! You lose.')
gameIsPlaying = False
else:
if isBoardFull(theBoard):
drawBoard(theBoard)
print('The game is a tie!')
break
else:
turn = 'player'

if not playAgain():
break


The output of the above program is as below:-

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