In this chapter, we discussed the hierarchical data structure and stored information in the form of a tree. We started our discussion by creating a tree from several TreeNodes, and then built a binary search tree where we can search for a given key easily. Sometimes, we can have a skewed tree in a binary search tree, and so we build an AVL tree, which can balance all of the elements itself, so that now we can have a balanced binary tree. Another tree data structure implementation is the binary heap, which we used to build a priority queue, where we can access an element based on its priority.
In the next chapter, we are going to discuss how to construct and implement the hash structure in algorithm design.