TIC TAC TOE- PROGRAM IT WITH PYTHON

So, here we go our first tutorial on programming. Let’s start the basic thing that every python programmer must have made . Yeah its nothing but a TIC TAC TOE game..


 

This uses an algorithm named “Minimax Algorithm. And yeah this code is strictly for PYTHON 3 not PYTHON 2.

the source code for this is here :-

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

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


 

So how does this algorithm works ?

here’s the answer. It follows some simple instructions that runs like this-

STEP 1check whether there’s a move where the computer can win. If yes take it and if not move to STEP 2 .

STEP2– check whether there’s a move where the player can win .If yes block it and if not move to STEP 3.

THIS IS THE STEP WHERE I MADE A LITTLE CHANGE THAN THE OTHER CODES THAT YOU’LL GET IN THE INTERNET. THIS CHANGE MAKES THE GAME UNBEATABLE HOWEVER THERE CAN BE TIE.

STEP3– check whether the center piece is empty. If yes take it if not move to STEP4.

STEP4– check whether the corners are empty . If yes take it if not move to STEP5.

STEP5– check whether the sides are empty . If yes take it .

when you reach to step 5 it means that the board is full and there isn’t any further moves available. 

Just try this code in your python 3 idle. And for any further information or explanation regarding this , feel free to mail me – sumanmukherjee2001@gmail.com.


 

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