Tic Tac Toe Error Python

Question

I'm having an indexing error with the following line of code, could someone please tell me what is wrong and why hopefully fix the error

for row in WAYS_TO_WIN:
    if board[row[0]] == board[row[1]] == board[row[2]] != EMPTY:
        winner = board[row[0]]
        return winner

The Full Code is:

def winner(board, EMPTY):
    #If you have won
    TIE = "TIE"
    WAYS_TO_WIN = ((1, 2, 3),
                   (4, 5, 6),
                   (7, 8, 9),
                   (1, 4, 7),
                   (2, 5, 8),
                   (3, 6, 9),
                   (1, 5, 9),
                   (3, 5, 7))

    for row in WAYS_TO_WIN:
        if board[row[0]] == board[row[1]] == board[row[2]] != EMPTY:
            winner = board[row[0]]
            return winner

Answer 1

As NUM_SQUARES == 9 and python is 0 indexed, the highest index you can access from the board is board[8] (which is the ninth place on the board).

so take 1 away from all of the numbers in WAYS_TO_WIN and it should be fine.

In more detail - the board is indexed from 0 through to 8, a total of 9 places. (0 being the first, 8 being the ninth). WAYS_TO_WIN has a minimum value of 1, and a max of 9. 1 is equivalent to the second place on the board, and 9 would be equivalent to the non-existent 10th place, which causes the error.