TicTacToe AI

#TIC TAC TOE with perfect brute force AI in Python 3
import time

board = [' ',' ',' ',' ',' ',' ',' ',' ',' ',' '] #index 1-9 represent board,
#according to layout of keys on numpad; 0 ignored

def printBoard(board): #prints a normal looking tic tac toe board
	print('\n ', board[7], ' | ', board[8], ' | ', board[9])
	print('------------------')
	print(' ', board[4], ' | ', board[5], ' | ', board[6])
	print('------------------')
	print(' ', board[1], ' | ', board[2], ' | ', board[3])

def choosePlayers(): #identifies which players are human and which are comps (ai)
	p1ok = False
	while p1ok == False:
		p1 = input('Is player 1 a human (h) or computer (c)?')
		if p1 == 'h' or p1 == 'c':
			p1ok = True
		else:
			print('Please enter a valid choice (h or c)')
	p2ok = False
	while p2ok == False:
		p2 = input('Is player 2 a human (h) or computer (c)?')
		if p2 == 'h' or p2 == 'c':
			p2ok = True
		else:
			print('Please enter a valid choice (h or c)')
	return (p1,p2)
	
def humanTurn(letter, board): #retrieves move from human player's input and changes the board accordingly
	printBoard(board)
	moveOk = False
	while moveOk == False:
		if letter == 'X':
			print('Player 1,', end=' ')
		elif letter == 'O':
			print('Player 2,', end=' ')
		move = input('enter the numpad position where you would like to move:')
		if move not in '123456789':
			print('Please enter a number (1-9)')
		elif board[int(move)] != ' ':
			print('That space is already occupied')
		else:
			board[int(move)] = letter
			moveOk = True
			
def compTurn(letter, board): #retrieves move from computer and changes board accordingly
	printBoard(board)
	(move,score) = compMove(letter, board)
	board[int(move)] = letter
	time.sleep(1) #pause 1 second
	return
	
def compMove(letter, board): #returns highest scoring move for whoever's turn it is;
#when investigating a move that doesn't end the game, the "score" of the move is reversed;
#since a high scoring move for your opponent is actually a low scoring move for you
#(see REVERSAL comments below)
	if letter == 'X':
		oppon = 'O'
	elif letter == 'O':
		oppon = 'X'
	moveList = makeList(board)
	moveListScore = []
	for i in range(len(moveList)):
		moveListScore.append(' ')
	for move in moveList:
		testBoard = board[:]
		testBoard[int(move)]=letter
		if checkForWin(testBoard) == letter:
			moveListScore[moveList.index(move)] = '9' #9 means instant win
		elif checkForTie(testBoard) == 'T':
			moveListScore[moveList.index(move)] = '5' #5 means instant tie
		elif checkForWin(testBoard) == oppon:
			moveListScore[moveList.index(move)] = '1' #1 means instant loss (needed?)
		else:
			theNextMove = compMove(oppon,testBoard)[1]
			if theNextMove == '9': #REVERSAL
				theNextMove = '1'
			elif theNextMove == '1': #OPPOSING REVERSAL
				theNextMove = '9'
			moveListScore[moveList.index(move)] = theNextMove
	for score in moveListScore: #remainder of function serves to
#pull the highest scoring move available
		if score == '9':
			return (moveList[moveListScore.index(score)],'9')
	for score in moveListScore:
		if score == '5':
			return (moveList[moveListScore.index(score)],'5')
	for score in moveListScore:
		if score == '1':
			return (moveList[moveListScore.index(score)],'1')
			
def makeList(board): #creates a string of all viable moves, e.g., '1346'
	myString = ''
	for i in range(1,10):
		if board[i]==' ':
			myString += str(i)
	return myString
	
def checkForWin(board): #searches for three in a row
	winner = 'W'
	if checkAllThree(1,2,3,board):
		winner = board[1]
	if checkAllThree(4,5,6,board):
		winner = board[4]
	if checkAllThree(7,8,9,board):
		winner = board[7]
	if checkAllThree(1,4,7,board):
		winner = board[1]
	if checkAllThree(2,5,8,board):
		winner = board[2]
	if checkAllThree(3,6,9,board):
		winner = board[3]
	if checkAllThree(1,5,9,board):
		winner = board[1]
	if checkAllThree(7,5,3,board):
		winner = board[7]
	return winner #W means no winner currently, X or O returned says which player wins;
#X is player 1; O is player 2
	
def checkAllThree(num1, num2, num3, board): #returns true if all three spaces are X or
#all three spaces are O
	if board[num1] == board[num2]:
		if board[num1] == board[num3]:
			if board[num1] == 'X' or board[num1] == 'O':
				return True
	return False
	
def checkForTie(board): #tie if all spaces are filled; must always check for win before checking for;
#tie since a winning board can also be filled
	tie = True
	for i in range(1,10):
		if board[i] == ' ':
			tie = False
	if tie:
		return 'T'
	else:
		return 'W' #W means no tie currently, T means the game is a tie
	
#MAIN
(player1Type, player2Type) = choosePlayers() #player1Type is an h or a c; same for player2Type
gameOver = 'W' #W means no winner, otherwise X or O
p1Turn = True
while gameOver == 'W': #game loop
	if p1Turn:
		if player1Type == 'h':
			humanTurn('X',board)
		elif player1Type == 'c':
			compTurn('X', board)
	if not p1Turn: #p2 turn
		if player2Type == 'h':
			humanTurn('O', board)
		elif player2Type == 'c':
			compTurn('O', board)
	p1Turn = not p1Turn
	if gameOver == 'W':
		gameOver = checkForWin(board)
	if gameOver == 'W':
		gameOver = checkForTie(board)
	if gameOver == 'X':
		printBoard(board)
		input('Player 1 is the winner! Press enter to exit')
	if gameOver == 'O':
		printBoard(board)
		input('Player 2 is the winner! Press enter to exit')
	if gameOver == 'T':
		printBoard(board)
		input('The game is a tie! Press enter to exit')