数据结构：对计算机内存中数据的一种安排。包括：数组、链表、栈、二叉树、哈希表等。

算法：对数据结构中的数据进行各种处理，例如查找特定项，排序等。

解决问题：现实世界中的数据存储，以前是用索引卡片（一叠卡片）来存储数据的，现在如果想用计算机来代替索引卡片（凡是用索引卡片的都可以用计算机代替），将会出现一些问题：

• How would youstore the datain your computer’s memory?                        --建模

• Would your method work for a hundred file cards? A thousand? A million?  --扩容

• Would your method permit quickinsertionof new cards anddeletionof old ones?

--插入、删除

• Would it allow forfast searchingfor a specified card?                                --查找

• Suppose you wanted to arrange the cards in alphabetical order. How would you sort them?                                                                                                                                                                                      --排序 

程序员的工具

有些数据结构只会在编程语言中用到，而不会被用户直接使用。

现实世界的建模

数据结构的特性（围绕查找、增加、删除的性能）

抽象数据结构：除了数组之外的数据结构。

算法的概述：插入删除查找，迭代查询、排序

Summary

• A data structure is the organization of data in a computer’s memory or in a disk file.

• The correct choice of data structure allows major improvements in program efficiency.

• Examples of data structures are arrays, stacks, and linked lists.

• An algorithm is a procedure for carrying out a particular task.

• In Java, an algorithm is usually implemented by a class method.

• Many of the data structures and algorithms described in this book are most often used to build databases.（数据库的原理看来不简单啊）

• Some data structures are used as programmer’s tools: They help execute an algorithm.

• Other data structures model real-world situations, such as telephone lines running between cities.(电话线网和数据结构有什么关系？也涉及到查询)

• A database is a unit of data storage composed of many similar records.

• A record often represents a real-world object, such as an employee or a car part.

• A record is divided into fields. Each field stores one characteristic of the object described by the record.

• A key is a field in a record that’s used to carry out some operation on the data.

For example, personnel records might be sorted by a LastName field.

• A database can be searched for all records whose key field has a certain value.

This value is called a search key.索引

关键字：当查询一条记录时，所使用的那个字段被称为(索引)关键字。