Thank you, that solved my problem :)

Oh, sorry. The last trained language on your profile was JS, so that was consistent with the usual mutation trouble and the way the tests were written.

I just checked, and the expected result for this input is effectively 1... but the ref solution actually returns 1 too... So I guess you're not looking at the input that is making your solution fail.

done

edit: btw: don't forget to give the language when you open an issue (yeah, was JS, I know ;p )

pro tip: don't ever mutate the input... I'll update the tests, but keep in mind this is very bad practice.

Maybe this hint will be useful? https://www.codewars.com/kata/5ce399e0047a45001c853c2b/discuss#5f29266f664ae7001042a4d7

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

The bounce doesn't pass the window.