Tic Tac Toe

tictactoe.py

from typing import List

R, C = 3, 3


def construct(board: List[List[int]]) -> str:
    """
    Constructs a tic tac toe board string based
    on a 2D list

    :param board: tic tac toe board as 2d list
    """
    ret = ""
    for i in range(R):
        for j in range(C):
            if board[i][j] == 2:
                ret += "| X |"
            elif board[i][j] == 1:
                ret += "| O |"
            else:
                ret += "|   |"
        ret += "\n"
    return ret


def won(board: List[List[int]]) -> bool:
    """
    Function that checks for valid `won` state
    Checks rows, columns and diagonals

    :param board: tic tac toe board as 2d list
    """
    for i in range(R):
        if len(set(board[i])) == 1 and 0 not in board[i]:
            return True

    columns = list(zip(*board))
    for i in range(C):
        if len(set(columns[i])) == 1 and 0 not in columns[i]:
            return True

    diag1, diag2 = [r[i] for i, r in enumerate(board)], [
        r[-i - 1] for i, r in enumerate(board)
    ]
    if (
        len(set(diag1)) == 1
        and 0 not in diag1
        or (len(set(diag2)) == 1 and 0 not in diag2)
    ):
        return True

    return False


def valid(r: int, c: int, board: List[List[int]]) -> bool:
    """
    Checks if a given (r, c) is a valid move

    :param r: row
    :param c: col
    :param board: tic tac toe board as 2d list
    """
    return not (r >= R or r < 0 or c >= C or c < 0 or board[r][c])


def full(board: List[List[int]]) -> bool:
    """
    Checks if board is full (there is a tie)

    :param board: tic tac toe board
    """
    for i in range(len(board)):
        for j in range(len(board)):
            if board[i][j] == 0:
                return False
    return True


def main() -> None:
    board = [[0, 0, 0] for i in range(R)]
    print("Player 1: 'O'\nPlayer 2: 'X'\n")

    p = 1
    while not won(board):
        if full(board):
            print("Tie!")
            exit()

        r, c = map(int, input("Player {} move: ".format(1 if p else 2)).split())

        if not valid(r, c, board):
            print("Invalid move.\n")
            continue

        board[r][c] = 1 if p else 2
        print("Board:\n{}\n".format(construct(board)))

        p ^= 1

    print("Player {} Wins!".format(1 if p ^ 1 else 2))


if __name__ == "__main__":
    main()