上下文无关文法（Context-Free Grammar, CFG）是一个4元组G=(V, T, S, P)，其中，V和T是不相交的有限集，S∈V，P是一组有限的产生式规则集，形如A→α，其中A∈V，且α∈(V∪T)*。V的元素称为非终结符，T的元素称为终结符，S是一个特殊的非终结符，称为文法开始符。 设G=(V, T, S, P)是一个CFG，则G产生的语言是所有可由G产生的字符串组成的集合，即L(G)={x∈T* | Sx}。一个语言L是上下文无关语言（Context-Free Language, CFL），当且仅当存在一个CFG G，使得L=L(G)。 *⇒ 例如，设文法G：S→AB A→aA|a B→bB|b 则L(G)={a^nb^m | n,m>=1} 其中非终结符都是大写字母，开始符都是S，终结符都是小写字母。
标签： Context-Free Grammar CFG
上传时间： 2013-12-10
上传用户：gaojiao1999
关于C++的一个PPT教程C++语言概述，包括介绍 2.2 基本数据类型和表达式 2.3 数据的输入与输出 2.4 算法的基本控制结构 2.5 自定义数据类型
上传时间： 2014-10-30
上传用户：zuozuo1215
We have a group of N items (represented by integers from 1 to N), and we know that there is some total order defined for these items. You may assume that no two elements will be equal (for all a, b: a<b or b<a). However, it is expensive to compare two items. Your task is to make a number of comparisons, and then output the sorted order. The cost of determining if a < b is given by the bth integer of element a of costs (space delimited), which is the same as the ath integer of element b. Naturally, you will be judged on the total cost of the comparisons you make before outputting the sorted order. If your order is incorrect, you will receive a 0. Otherwise, your score will be opt/cost, where opt is the best cost anyone has achieved and cost is the total cost of the comparisons you make (so your score for a test case will be between 0 and 1). Your score for the problem will simply be the sum of your scores for the individual test cases.
标签： represented integers group items
上传时间： 2016-01-17
上传用户：jeffery
The XML Toolbox converts MATLAB data types (such as double, char, struct, complex, sparse, logical) of any level of nesting to XML format and vice versa. For example, >> project.name = MyProject >> project.id = 1234 >> project.param.a = 3.1415 >> project.param.b = 42 becomes with str=xml_format(project, off ) "<project> <name>MyProject</name> <id>1234</id> <param> <a>3.1415</a> <b>42</b> </param> </project>" On the other hand, if an XML string XStr is given, this can be converted easily to a MATLAB data type or structure V with the command V=xml_parse(XStr).
标签： converts Toolbox complex logical
上传时间： 2016-02-12
上传用户：a673761058
Javascript网页脚本编程基础的，介绍了Javascript语言的概况、基本数据结构，程序构成
标签： Javascript 页 脚本 编程
上传时间： 2016-06-12
上传用户：363186
这是一个c++程序，实现了诸如堆栈，链表，二叉树之类的基本数据结构
标签： 程序
上传时间： 2013-12-06
上传用户：tianjinfan
嵌入式linux 设备驱动程序，控制开关输出，是写驱动最基本的结构显示。
上传时间： 2013-12-17
上传用户：tfyt
介绍了QNX实时操作系统和多线程编程技术，包括线程间同步的方法、多线程程序的分析步骤、线程基本程序结构以及实用编译方法
上传时间： 2014-12-21
上传用户：498732662
汉诺塔！！！ Simulate the movement of the Towers of Hanoi puzzle Bonus is possible for using animation eg. if n = 2 A→B A→C B→C if n = 3 A→C A→B C→B A→C B→A B→C A→C
标签： the animation Simulate movement
上传时间： 2017-02-11
上传用户：waizhang
伸展树，基本数据结构，The tree is drawn in such a way that both of the edges down from a node are the same length. This length is the minimum such that the two subtrees are separated by at least two blanks.
标签： 树
上传时间： 2017-05-07
上传用户：JIUSHICHEN
