Up until this chapter, data structures have only become faster for searching, and this chapter is no different. What makes it different is why and how data can be found in two higher-level data structures: maps and sets. While the former is also known as dictionary, associative array, object, or hash table, the latter commonly crosses people's minds as a mathematical concept. Both can rely on hashing, a technique that allows for constant (or close to constant) time retrieval of items, checking whether they are contained in a set, or routing requests in distributed hash tables.

These data structures are also one level higher than the previous ones, since all of them build on existing structures, such as dynamic arrays or trees, and to top things off, the chapter starts with an algorithm. Understanding this chapter will be great preparation heading into...