There are now many last elements. By careful consideration of such restrictions, we can develop a number of different interesting structures. We can generalize search trees to develop a data structure commonly called trees . In binary trees , each node can have at most two children, often designated as left and right . A node stores a value.
All smaller values are in the left subtree.
All larger values are in the right subtree. The left and right subtrees are also heaps. The tree is nearly-complete. Trees are good for hierarchical structures, like advising relationships in graduate school. A Tree ADT Purposefully left open.