ttt

"""
Tic Tac Toe Player
"""

import math
import runner as rn


X = "X"
O = "O"
EMPTY = None


def initial_state():
    """
    Returns starting state of the board.
    """
    return [[EMPTY, EMPTY, EMPTY],
            [EMPTY, EMPTY, EMPTY],
            [EMPTY, EMPTY, EMPTY]]


def player(board):
    """
    Returns player who has the next turn on a board.
    """
    flat_board = [item for sublist in board for item in sublist] # flatten the list of list

    Xs = sum(x==X for x in flat_board) # count nb of Xs in board
    Os = sum(x==O for x in flat_board) # and Os

    if Xs < Os:
        res = X
    elif Xs > Os:
        res = O
        # break a tie check the starting user
    elif rn.user == X: # None check already done in runner before this call
        res = 0
    else:
        res = X
    return res


def actions(board):
    """
    Returns set of all possible actions (i, j) available on the board.
    """
    raise NotImplementedError


def result(board, action):
    """
    Returns the board that results from making move (i, j) on the board.
    """
    return [[O, EMPTY, EMPTY],
            [EMPTY, EMPTY, EMPTY],
            [EMPTY, EMPTY, EMPTY]]


def winner(board):
    """
    Returns the winner of the game, if there is one.
    """
    raise NotImplementedError


def terminal(board):
    """
    Returns True if game is over, False otherwise.
    """
    return False


def utility(board):
    """
    Returns 1 if X has won the game, -1 if O has won, 0 otherwise.
    """
    raise NotImplementedError


def minimax(board):
    """
    Returns the optimal action for the current player on the board.
    """
    return [2,1]