def dmp_exquo_ground(f, c, u, K):
    """
    Exact quotient by a constant in ``K[X]``.

    Examples
    ========

    >>> R, x, y = ring("x y", QQ)

    >>> R.dmp_exquo_ground(x**2*y + 2*x, QQ(2))
    1/2*x**2*y + x

    """
    if not u:
        if not c:
            raise ZeroDivisionError('polynomial division')
        if not f:
            return f

        return [K.exquo(coeff, c) for coeff in f]

    v = u - 1
    return [dmp_exquo_ground(coeff, c, v, K) for coeff in f]