Bouncing Balls.py

# A child is playing with a ball on the nth floor of a tall building. The height of this floor above ground level, h, is known.

# He drops the ball out of the window. The ball bounces (for example), to two-thirds of its height (a bounce of 0.66).

# His mother looks out of a window 1.5 meters from the ground.

# How many times will the mother see the ball pass in front of her window (including when it's falling and bouncing)?

# Three conditions must be met for a valid experiment:
# Float parameter "h" in meters must be greater than 0
# Float parameter "bounce" must be greater than 0 and less than 1
# Float parameter "window" must be less than h.
# If all three conditions above are fulfilled, return a positive integer, otherwise return -1.

# Note:
# The ball can only be seen if the height of the rebounding ball is strictly greater than the window parameter.

# Examples:
# - h = 3, bounce = 0.66, window = 1.5, result is 3

# - h = 3, bounce = 1, window = 1.5, result is -1 

# (Condition 2) not fulfilled).

def bouncing_ball(h, bounce, window):
    # h is height above ground floor
    # bounce is how high the ball bounces after dropping
    # window is height that the ball is seen at. 
    # trying to get the range until bounceback height is less than window
    if h <= 0 or bounce <= 0 or bounce >= 1 or window >= h:
        return -1

    height = h
    count = 0
    while height > window:
        height *= bounce
        count += 1
        if height > window:
                count += 1
    return count