some books describe pumping lemma as this: Let L be a regular language. Then there exists an integer p ≥ 1 depending only on L such that every string w in L of length at least p (p is called the "pumping length"[4]) can be written as w = xyz (i.…

什么是有限状态机(Finite State Machine)? 什么是确定性有限状态机(deterministic finite automaton, DFA )? 什么是非确定性有限状态机(nondeterministic finite automaton, NDFA, NFA)? [1] wiki-en: Finite state machine [2] wiki-zh-cn: Finite state machine [3] brilliant: finite-state-machines…

1.问题概述 NFA 和 DFA浅析---要深入了解正则表达式,必须首先理解有穷自动机. 有穷自动机(Finite Automate)是用来模拟实物系统的数学模型,它包括如下五个部分: 有穷状态集States 输入字符集Input symbols 转移函数Transitions 起始状态Start state 接受状态Accepting state(s)(终止状态) 下图为一台有穷自动机…

catalog . 引论 . 构建一个编译器的相关科学 . 程序设计语言基础 . 一个简单的语法制导翻译器 . 简单表达式的翻译器(源代码示例) . 词法分析 . 生成中间代码 . 词法分析器的实现 . 词法分析器生成工具Lex . PHP Lex(Lexical Analyzer) . 语法分析 . 构造可配置词法语法分析器生成器 . 基于PHP Lexer重写一份轻量级词法分析器 . 在Opcode层面进行语法还原WEBSHELL检测 0. 引论 在所有计算机上运行的所有软件都是用某种程序设…

Difference of Languages Time Limit: 1000ms Memory Limit: 32768KB This problem will be judged on HDU. Original ID: 548764-bit integer IO format: %I64d      Java class name: Main A regular language can be represented as a deterministic finite automaton…

4.2 Context-Free Grammars Grammars were introduced in Section 2.2 to systematically describe the syntax of programming language constructs like expressions and statements. Using a syntactic variable stmt to denote statements and variable expr to deno…

http://www-igm.univ-mlv.fr/~lecroq/string/node14.html Main features performs the comparisons from right to left; preprocessing phase in O(m+) time and space complexity; searching phase in O(mn) time complexity; 3n text character comparisons in the wo…

首页:http://yuanjisuan.cn/ 有限元语言及其编译器(Finite Element Language And it’s Compiler),以下简称FELAC是中国科学院数学与系统科学研究院梁国平研究员于1983年开始研发的通用有限元软件平台,是具有国际独创性的有限元计算软件,是PFEPG系列软件三十年成果(1983年—2013年)的总结与提升,有限元语言语法比PFEPG更加简练,更加灵活,功能更加强大.目前已发展到2.0版本.其核心采用元件化思想来实现有限元计算的基本工序,采…

Basic concepts of speech Speech is a complex phenomenon. People rarely understand how is it produced and perceived. The naive perception is often that speech is built with words, and each word consists of phones. The reality is unfortunately very dif…

题目简述:给定$1 \leq l \leq r \leq 10^{800}$,求一个长度为$n \leq 2000$的数字串$s$,其含有最多的[好]子串.一个串$s$是[好]的,如果将其看做数字时无前导零且满足$l \leq s \leq r$.形式化的说,就是求 $$ \arg \max_{s \in \Sigma^n} \sum_{i=1}^n \sum_{j=i}^n [s[i] \neq 0 \land l \leq s[i \dots j] \leq r] , $$ 其中$\Sigm…

4.7.4 Constructing LALR Parsing Tables We now introduce our last parser construction method, the LALR (lookahead-LR) technique. This method is often used in practice, because the tables obtained by it are considerably smaller than the canonical LR ta…

什么是正则表达式? 正则表达式是一组由字母和符号组成的特殊文本, 当你想要判断许多字符串是否符合某个特定格式:当你想在一大段文本中查找出所有的日期和时间:当你想要修改大量日志中所有的时间格式,在这些情况下,正则表达式都能帮上忙. 简单来说,正则表达式描述了一系列规则,通过这些规则,可以在字符串中找到相关的内容,规则使得搜索的能力更加强大.匹配的过程由正则表达式引擎完成.开发者通常不需要关心正则表达式引擎的实现细节,直接使用其提供的能力即可. 大家可以先想象你正在写一个应用, 然后你想设定一个用户…

MySQL :: MySQL 8.0 Reference Manual :: 8.3.9 Comparison of B-Tree and Hash Indexes https://dev.mysql.com/doc/refman/8.0/en/index-btree-hash.html If you use ... LIKE '%string%' and string is longer than three characters, MySQL uses the Turbo Boyer-Moo…

Contents Tutorial Hello, World Command-Line Arguments Finding Duplicate Lines A Web Server Loose Ends Program Structure Names Declarations Variables Assignments Type Declarations Packages and Files Scope Basic Data Types Integers Floating-Point Numbe…

Lemma 21.2 (The sequence lemma) Let \(X\) be a topological space; let \(A \subset X\). If there is a sequence of points of \(A\) converging to \(x\), then \(x \in \bar{A}\); the converse holds if \(X\) is metrizable. Proof a) Sequence convergence \(\…

Speech and Natural Language Processing obtain from this link: https://github.com/edobashira/speech-language-processing A curated list of speech and natural language processing resources. Other lists can be found in this list. If you want to contribut…

最近代码写的少了,而leetcode一直想做一个python,c/c++解题报告的专题,c/c++一直是我非常喜欢的,c语言编程练习的重要性体现在linux内核编程以及一些大公司算法上机的要求,python主要为了后序转型数据分析和机器学习,所以今天来做一个难度为hard 的简单正则表达式匹配. 做了很多leetcode题目,我们来总结一下套路: 首先一般是检查输入参数是否正确,然后是处理算法的特殊情况,之后就是实现逻辑,最后就是返回值. 当编程成为一种解决问题的习惯,我们就成为了一名纯粹的程序…

A Pattern Language for Parallel Application Programming Berna L. Massingill, Timothy G. Mattson, Beverly A. Sanders Abstract Parallel computing has failed to attract significant numbers of programmers outside the specialized world of supercomputing.…

catalog . PCRE Introduction . pcre2api . pcre2jit . PCRE Programing 1. PCRE Introduction The PCRE library is a set of functions that implement regular expression pattern matching using the same syntax and semantics as Perl 5. PCRE has its own native…

D. Regular Bridge time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output An undirected graph is called k-regular, if the degrees of all its vertices are equal k. An edge of a connected graph is c…

Regular expressions are a language of their own. When you learn a new programming language, they're this little sub-language that makes no sense at first glance. Many times you have to read another tutorial, article, or book just to understand the "s…

http://docs.oracle.com/javase/tutorial/essential/regex/index.html This lesson explains how to use the java.util.regex API for pattern matching with regular expressions. Although the syntax accepted by this package is similar to the Perl programming l…

Regular expressions are a language of their own. When you learn a new programming language, they're this little sub-language that makes no sense at first glance. Many times you have to read another tutorial, article, or book just to understand the "s…

题目: Implement regular expression matching with support for '.' and '*'. '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). The function prototype shoul…

Regular expressions are a powerful language for matching text patterns. This page gives a basic introduction to regular expressions themselves sufficient for our Python exercises and shows how regular expressions work in Python. The Python "re"…

0x01 从判定问题到形式语言 这篇讲知识证明的wiki([1]): https://en.wikipedia.org/wiki/Proof_of_knowledge 里面有一句话: Let x be a language element of language L in NP 这篇讲NPC的文章([2]) http://www.cs.princeton.edu/courses/archive/spr11/cos423/Lectures/NP-completeness.pdf 里面提到Decis…

It's a very elegant summary of regular expression from The AWK Programming Language. 1. The regular expression metacharacters are: \ ^ $ . [ ] | ( ) * + ? 2. A basic regular expression is one of the following: a nonmetacharacter, such as A, that matc…

程序 C# 程序(program)由至少一个源文件(source files)组成,其正式称谓为编译单元(compilation units)[1].每个源文件都是有序的 Unicode 字符序列.源文件通常与文件系统内的相应文件具有一对一关系,但这种相关性并非必须因素.为尽最大可能确保可移植性,推荐文件系统中的文件编码为 UTF-8 编码规范. 从理论上来说,程序编译由三步骤组成: 转换(transformation),将文件中的特定字符编码方案转换为 Unicode 字符序列: 词法分析(l…

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-23.4 Draft Report Errors and Issues at: https://bugs.ecmascript.org Product: Draft for 6th Edition Component: choose an appropriate one Version: Rev 27, August 24, 2014 Draft Ecma/TC39/2014/0xx…

The Go Programming Language Specification go语言规范 Version of May 9, 2018 Introduction 介绍 Notation 符号 Source code representation 源代码表示形式 Characters 字符 Letters and digits 字母和数字 Lexical elements 词法元素 Comments 评论 Tokens 令 牌 Semicolons 分号 Identifiers 标识符 K…