What are some situations where hash maps are useful?
Hash maps can be used to solve many problems that require the need to associate things (key-value pairs) and to quickly assign and retrieve them.
Hash maps apply to many important areas such as databases, where user id’s map to their information. For companies with tens of millions of users, it is important to be able to perform quick lookups.
Because of its fast speed for doing assignment and retrieval, hash maps are a popular data structure used by many programmers when trying to solve certain problems. For example, how might you keep track of how many times each letter of the alphabet appears in a book? We can use a hash map with each index corresponding to a letter, with the values being their count.