Balanced tree, advanced data structures, a powerful tool for maintaining a prefix successor, variety. Treap which because of its relatively simple code to write, to become one of the major competitions balanced tree; splay with a strong range of modifications, and a relatively small amount of code to be another contest balanced tree.
In this chapter, we will continue to learn the balance of the tree pre --BST, Treap, Splay. Of course, we'll dabble FHQ.
The future may also have a wider variety of balanced tree, such as: scapegoat tree, red-black tree, SBT ...... Interested readers can look online.