Created game TicTacToe_AI.py

Tic tac toe game using minimax algo, where computer never lose.

games/minimax/TicTacToe_AI.py

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+# tic tac toe game with minimax algorithm, Its impossible to beat opponent...
+
+from math import inf as infinity
+import random
+
+# initially board is empty..
+board = {1 : ' ', 2 : ' ', 3 : ' ',
+         4 : ' ', 5 : ' ', 6 : ' ',
+         7 : ' ', 8 : ' ', 9 : ' '}
+
+# reference board print...
+def demoBoard(board):
+    print(" ** REFERENCE POSITIONS **")
+    count = 0
+    for each in board:
+        count += 1
+        if(count % 3 != 0):
+            print(count , end=" | ")
+        else:
+            print(count)
+            if(count != 9):
+                print('-'*10)
+
+    print('_'*18)
+
+
+class TicTacToe(object):
+    def __init__(self, board):
+        self.board = board
+
+        #  printing current board...
+        count = 0
+        print()
+        for each in board:
+            count += 1
+            if(count % 3 != 0):
+                print(board[each] , end=" | ")
+            else:
+                print(board[each])
+                if(count != 9):
+                    print('-'*10)
+
+
+    def isSpacefree(self, position):
+        if(position in range(10) and board[position] == " "):
+            return True
+        else:
+            return False
+
+
+    def checkWin(self, board):
+        # row
+        if(board[1] == board[2] == board[3] != " "):
+            return [True, board[1]]
+        elif(board[4] == board[5] == board[6] != " "):
+            return [True, board[4]]
+        elif(board[7] == board[8] == board[9] != " "):
+            return [True, board[7]]
+        # column
+        elif(board[1] == board[4] == board[7] != " "):
+            return [True, board[1]]
+        elif(board[2] == board[5] == board[8] != " "):
+            return [True, board[2]]
+        elif(board[3] == board[6] == board[9] != " "):
+            return [True, board[3]]
+        # diagonal
+        elif(board[1] == board[5] == board[9] != " "):
+            return [True, board[1]]
+        elif(board[3] == board[5] == board[7] != " "):
+            return [True, board[3]]
+
+        else:
+            return [False]
+
+    # if board is full and no winner..
+    def checkDraw(self, board):
+        # if board is fully filled...
+        if(not any([True if board[x] == ' ' else False for x in board])):
+            return True
+
+        return False
+
+
+    def insertPosition(self, position, letter = 'O'):
+        if(self.isSpacefree(position)):
+            board[position] = letter
+            self.__init__(board)
+            res = self.checkWin(board)
+            if(res[0]):
+                print(f'  Player {res[1]} won  ')
+                exit()
+
+            # if board is fully filled and none is winner then it is a draw...  
+            if(not any([True if board[x] == ' ' else False for x in board]) and not res[0]):
+                print("  *** Draw *** ")
+                exit()
+
+        else:
+            position = int(input("  ==>> Space is either not free or NOT valid choose valid position..  "))
+            self.insertPosition(position)
+
+
+
+    def playerMove(self, letter='O'):
+        position = int(input(" You move - Choose Position :  "))
+        self.insertPosition(position, letter)
+
+
+    def MiniMax(self, board, depth, isMaximizing):
+        # check for base conditions who won..
+        winner = self.checkWin(board)
+        if(winner[0]):
+            # 'X' = bot, 'O' = player
+            # return 1 if(winner[1] == 'X') else -1
+            empty_spaces = [1 if board[x] == ' ' else 0 for x in board].count(1)
+            if(winner[1] == 'X'):
+                return 1*(empty_spaces + 1)
+            else:
+                return -1*(empty_spaces + 1)
+
+        elif(self.checkDraw(board)):
+            return 0
+
+        if(isMaximizing):
+            bestScore = -infinity
+            for each in board:
+                if(board[each] == " "):
+                    board[each] = 'X'
+                    # calling the minimax function for letter 'O'
+                    score = self.MiniMax(board, 0, False)
+                    # undo the move for next iter check
+                    board[each] = " "
+                    bestScore = max(score, bestScore)
+
+            return bestScore
+
+        else:
+            bestScore = infinity
+            for each in board:
+                if(board[each] == " "):
+                    board[each] = 'O'
+                    # calling the minimax function with letter 'X' for maximization
+                    score = self.MiniMax(board, 0, True)
+                    # undo the move for next iter check
+                    board[each] = " "
+                    bestScore = min(score, bestScore)
+
+            return bestScore
+
+
+    def computerMove(self, letter='X'):
+        print(" Computer Playing his move..")
+        bestMove = 0
+        bestScore = -infinity
+
+        for each in board:
+            if(board[each] == " "):
+                board[each] = letter
+                # calling the minimax function for letter 'O'
+                score = self.MiniMax(board, 0, False)
+                # undo the move for next iter check
+                board[each] = " "
+                # maxEval = max(eval, maxEval)
+                if(score > bestScore):
+                    bestScore = score
+                    bestMove = each
+
+        self.insertPosition(bestMove, letter)
+        return
+
+
+
+demoBoard(board)
+obj = TicTacToe(board)
+
+# loop will run until game is not over..
+while(True):
+    obj.computerMove('X')
+    obj.playerMove('O')
+
+# end