lol for sure!

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

That's in the description.

For what i undestood if the ball jumps just to the height of the window, then the mom should see it either zero or once. I think it's counted as zero since it doesn't pass her laser eyes

It means the correct answer is -1.

Language? The test in C++ is like this:

testequal(Bouncingball::bouncingBall(2, 0.5, 1), 1);