bouncing_balls.py

def bouncingBall(h, bounce, window):
    """A child plays with a ball on the nth floor of a big building.
    The height of this floor is known:

    (float parameter "h" in meters, h > 0) .

    He lets out the ball. The ball rebounds for example to two-thirds:

    (float parameter "bounce", 0 < bounce < 1)

    of its height.

    His mother looks out of a window that is 1.5 meters from the ground:

    (float parameters window < h).

    How many times will the mother see the ball either falling or
    bouncing in front of the window

    (return a positive integer unless conditions are not fulfilled
    in which case return -1) ?

    Note

    You will admit that the ball can only be seen if the height
    of the rebouncing ball is stricty greater than the window parameter.

    Example:

    h = 3, bounce = 0.66, window = 1.5, result is 3

    h = 3, bounce = 1, window = 1.5, result is -1
    """
    if h <= 0 or bounce <= 0 or bounce >= 1 or window >= h:
        return -1
    count = 1
    while h * bounce > window:
        h *= bounce
        count += 2

    return count