MemoManager class has a method named $$addToTree$$ which takes a Memo object and a key $($the

type of key can be Date or String$)$ to add to the bTreeDate and bTreeTitle

MemoManager class has a method named $$findMemo$$ which takes a searching key and returns the

memo that matches the searching key by calling binaryTree. searchElement$($key$).$ If the memo does

not exist, it returns null.

MemoManager class has a method named $$getSortedMemoList$$ which takes a key $($the type of key

can be Date or String$)$ and returns a memo array. The elements in the memo array must be sorted.

MemoManager class has a method named $$reverseOrder$$ which calls the BinaryTree objects to

reverse the order of the trees.