import numpy as np
import sys
from copy import copyrows = 3
cols = 3board = np.zeros((rows,cols))inf = float("inf")
neg_inf = float("-inf")def printBoard():for i in range(rows):for j in range(cols):if board[i, j] == 0:sys.stdout.write(' _ ')elif board[i, j] == 1:sys.stdout.write(' X ')else:sys.stdout.write(' O ')print ''# The heuristic function which will be evaluating board's position for each of the winning POS
heuristicTable = np.zeros((rows+1, cols+1))
numberOfWinningPositions = rows + cols + 2for index in range(rows+1):heuristicTable[index, 0] = 10**indexheuristicTable[0, index] =-10**indexwinningArray = np.array([[0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6]])def utilityOfState(state):stateCopy = copy(state.ravel())heuristic = 0for i in range(numberOfWinningPositions):maxp = 0minp = 0for j in range(rows):if stateCopy[winningArray[i,j]] == 2:maxp += 1elif stateCopy[winningArray[i,j]] == 1:minp += 1heuristic += heuristicTable[maxp][minp]return heuristicdef minimax(state,alpha,beta,maximizing,depth,maxp,minp):if depth==0:return utilityOfState(state),staterowsLeft,columnsLeft=np.where(state==0)returnState=copy(state)if rowsLeft.shape[0]==0:return utilityOfState(state),returnStateif maximizing==True:utility=neg_inffor i in range(0,rowsLeft.shape[0]):nextState=copy(state)nextState[rowsLeft[i],columnsLeft[i]]=maxp#print 'in max currently the Nextstate is ',nextState,'\n\n'Nutility,Nstate=minimax(nextState,alpha,beta,False,depth-1,maxp,minp)if Nutility > utility:utility=NutilityreturnState=copy(nextState)if utility>alpha:alpha=utilityif alpha >=beta :#print 'pruned'break;#print 'for max the best move is with utility ',utility,' n state ',returnStatereturn utility,returnStateelse:utility=inffor i in range(0,rowsLeft.shape[0]):nextState=copy(state)nextState[rowsLeft[i],columnsLeft[i]]=minp#print 'in min currently the Nextstate is ',nextState,'\n\n'Nutility,Nstate=minimax(nextState,alpha,beta,True,depth-1,maxp,minp)if Nutility < utility:utility=NutilityreturnState=copy(nextState)if utility< beta:beta=utilityif alpha >=beta :#print 'pruned'break;return utility,returnStatedef checkGameOver(state):stateCopy=copy(state)value=utilityOfState(stateCopy)if value >=1000:return 1return -1def main():num=input('enter player num (1st or 2nd) ')value=0global boardfor turn in range(0,rows*cols):if (turn+num)%2==1: #make the player go first, and make the user player as 'X'r,c=[int(x) for x in raw_input('Enter your move ').split(' ')]board[r-1,c-1]=1printBoard()value=checkGameOver(board)if value==1:print 'U win.Game Over'sys.exit()print '\n'else: #its the computer's turn make the PC always put a circle'#right now we know the state if the board was filled by the other player state=copy(board)value,nextState=minimax(state,neg_inf,inf,True,2,2,1)board=copy(nextState)printBoard()print '\n'value=checkGameOver(board)if value==1:print 'PC wins.Game Over'sys.exit()print 'Its a draw'if __name__ == "__main__":main()