In the example graphic, I understand that each Entry has a right and left "child" Entry, or at least the potential to have them. I also understand that if you remove an Entry (such as in the example list.remove("3")) it removes all the child entries as well. But I do not understand the placement of the example list.add("16"). Why does it branch off of 9? Isn't the left child for entry 1 available again at this point? If the slots for entry children do not become available after they are emptied, would this imply that removing entry 1 and entry 2 would leave a root entry 0 that cannot have anything else added to it? Also, what happens if, instead of list.add("16") I used list.add("20")? Would it still go under the left child of entry 9, or would it place it where it would be if all the in-between entries had been placed first?
The intended design of this tree is not clear from the instructions