30 Line Tic Tac Toe

tictactoe.py

import random
wins = [(0,1,2),(3,4,5),(6,7,8),(0,3,6),(1,4,7),(2,5,8),(0,4,8),(6,4,2),]

def checkwin(board):
    for win in wins:
        if board[win[0]] == board [win[1]] == board[win[2]] is not None:
            return board[win[0]]
    return None if None in board else .5

def maximize(board, target, index):
    moves = []
    for i in range(9):
        if board[i] is None:
            board2 = board[:]
            board2[i] = target
            moves.append((checkwin(board2) if checkwin(board2) is not None else maximize(board2, 1-target, index - 1)[0] ,i))
    return (.5, random.choice(moves)[1]) if index <= 0 else sorted(moves,key=lambda x:abs(target-x[0]) + random.random()/10.0)[0]

board = [None]*9
move = input("start? (0=start, 1=wait) ")
while checkwin(board) is None:
    if move == 0:
        space = input("Move? (1-9) ")
        board[space-1] = 0
    else:
        board[maximize(board, 1, 9)[1]] = 1
    move = 1-move
    for i in range(0,7,3):
        print "".join([("X","O")[board[j]] if board[j] is not None else "_" for j in range(i,i+3)])