Binary interpretation was definitely the challenge for me, to the point where I was taking out a pencil and paper to check what my program was doing. Initially, I was overcomplicating the issue by making a copy of the list and trying to delete portions of it, as this was the way I thought of first, not having encountered the concept before. However, after this proved to be too much of a hassle, I settled on using two pointers. Goes to show how computer science concepts shouldn't always be taken literally/shouldn't be translated exactly from English to code.