-- exercise 3.1 (prove right-spine contains at most floor(log(n + 1)) elements)
-- - binary tree; observe that rightmost-weighted binary tree obeying leftist
--   property is balanced.
-- - right spine length is maximized in balanced case.
-- - tree has depth floor(log(n + 1)) in balanced case.
-- - right spine has at most floor(log(n + 1)) elements.

-- exercise 3.2 (define insert directly rather than by merge)
altInsert :: Ord a => a -> Heap a -> Heap a
altInsert e  Leaf            = singleton e
altInsert :: Ord a => a -> Heap a -> Heap a
altInsert e  Leaf            = singleton e
altInsert e  Leaf            = singleton e