2018-06-10

Joel Spolsky的七个建议

毕业前练好写作表达能力->影响力
毕业前学好C语言
- C语言仍然是当前程序员的共同语言
- 你能解释为什么while (*s++ = *t++)；这句代码的作用是复制字符串吗？
毕业前学好微观经济学商业领域所有重要理论的基础
你一定要去学微观经济学，因为你必须搞懂供给和需求，你必须明白竞争优势，你必须理解什么是净现值（NPV），什么是贴现，什么是边际效用。只有这样，你才会懂得为什么生意是现在这种做法。
- 从经营一家公司的角度来看，比起那些不懂的程序员，一个理解基本商业规则的程序员将会更有价值。
- 别忘了，在编程工作中也有很枯燥的东西。每一项工作都有枯燥难耐的时刻。我不想雇用那些只想干有趣事情的人。
选修有大量编程实践的课程
- 计算机科学与软件开发不是一回事。
别担心所有工作都被印度人抢走
找一份好的暑期实习工作

2018-06-10

Java点点

Java语法

final域
final域一旦赋值后将永远不变，因此非常适合用来定义常量。值得注意的是：如果final域是一个基本类型，那么表明改域的值是不能改变的。若final域是一个对象的引用，则仅仅表明改引用不能被改变，也就是永远指向同一个对象，但是被引用的对象自身却是可以改变的。这跟c++中的常量指针很像（不是指向常量的指针）。初始化final域有着特殊的要求：非静态final域要求在构造函数执行后必须被明确赋值，而静态final域在类初始化完成后必须要被明确赋值。
JAR地狱（JAR hell）：JAR文件不同版本或路径带来的问题，通常是由于不懂类加载模型导致的。指类路径里JAR包太多这个问题。另外一个“JAR地狱”的解释是“反模式”中的一个概念。DLL地狱（DLL hell）：不同版本带来的问题，DLL可见性和多版本问题，在微软的Windows上尤为突出
ThreadLocal
A ThreadLocal can be used to avoid the creation of a new SimpleDateFormat for each call.
It is needed in a multithread context since the SimpleDateFormat is not thread safe

Spring

Jackson Annotations

@JsonIgnoreProperties one of the most common annotations in Jackson – is used to mark a property or a list of properties to be ignored at the class level.如果是代理类，由于无法标记在属性或方法上，所以，可以标记在类声明上；也作用于反序列化时的字段解析。作用在类上，用来说明有些属性在序列化/反序列化时需要忽略掉，可以将它看做是@JsonIgnore的批量操作，但它的功能比@JsonIgnore要强，比如一个类是代理类，我们无法将将@JsonIgnore标记在属性或方法上，此时便可用。标注在类声明上，它还有一个重要的功能是作用在反序列化时解析字段时过滤一些未知的属性，否则通常情况下解析到我们定义的类不认识的属性便会抛出异常。
@JsonIgnore The @JsonIgnore annotation is used to mark a property to be ignored at the field level.一般标记在属性或方法上；作用于序列化与反序列化。作用在字段或方法上，用来完全忽略被注解的字段和方法对应的属性，即便这个字段或方法可以被自动检测到或者还有其他的注解
@JsonPropertyOrder，注释在类声明中
@JsonAutoDetect 看上面自动检测，不再重复
@JsonProperty 作用在字段或方法上，用来对属性的序列化/反序列化，可以用来避免遗漏属性，同时提供对属性名称重命名，比如在很多场景下Java对象的属性是按照规范的驼峰书写，但是实际展示的却是类似C-style或C++/Microsolft style
@JsonUnwrapped 作用在属性字段或方法上，用来将子JSON对象的属性添加到封闭的JSON对象
@JsonIdentityInfo 2.0+版本新注解，作用于类或属性上，被用来在序列化/反序列化时为该对象或字段添加一个对象识别码，通常是用来解决循环嵌套的问题，比如数据库中的多对多关系，通过配置属性generator来确定识别码生成的方式，有简单的，配置属性property来确定识别码的名称，识别码名称没有限制。
@JsonNaming jackson 2.1+版本的注解，作用于类或方法，注意这个注解是在jackson-databind包中而不是在jackson-annotations包里，它可以让你定制属性命名策略，作用和前面提到的@JsonProperty的重命名属性名称相同。

多态类型处理

jackson允许配置多态类型处理，当进行反序列话时，JSON数据匹配的对象可能有多个子类型，为了正确的读取对象的类型，我们需要添加一些类型信息。可以通过下面几个注解来实现：

@JsonTypeInfo 作用于类/接口，被用来开启多态类型处理，对基类/接口和子类/实现类都有效

工具

9 tools to help you with Java Performance Tuning
http://blog.idrsolutions.com/2014/06/java-performance-tuning-tools/

JWT

JWT是 Json Web Token 的缩写。它是基于 RFC 7519 标准定义的一种可以安全传输的小巧和自包含的JSON对象。由于数据是使用数字签名的，所以是可信任的和安全的。JWT可以使用HMAC算法对secret进行加密或者使用RSA的公钥私钥对来进行签名。

JWT是由三段组成的，按官方的叫法分别是header（头）、payload（负载）和signature（签名）：

header.payload.signature

一个比较成熟的JWT类库，叫 jjwt ( https://github.com/jwtk/jjwt )。这个类库可以用于Java和Android的JWT token的生成和验证。

Java JWT: JSON Web Token for Java and Android
https://github.com/jwtk/jjwt

JWTs are incredibly cool for authentication because they let us implement reliable Single Sign-On (SSO) with low overhead on any platform (native, web, VR, whatever…) and across domains. JWTs are a strong alternative to pure cookie or session based auth with simple tokens or SAML, which can fail miserably in native app implementations. We can even use cookies with JWTs if we really want.

For our purposes, we just need to know how to use JWTs within our authentication workflow. When a user logs into our app, the server will check their email and password against the database. If the user exists, we’ll take their {email: , password: } combination, turn it into a lovely JWT, and send it back to the client. The client can store the JWT forever or until we set it to expire.

Whenever the client wants to ask the server for data, it’ll pass the JWT in the request’s Authorization Header (Authorization: Bearer ). The server will decode the Authorization Header before executing every request, and the decoded JWT should contain {email: , password: }. With that data, the server can retrieve the user again via the database or a cache to determine whether the user is allowed to execute the request.

The Expired Password Problem
We still have one last thing that needs modifying in our authorization setup. When a user changes their password, we issue a new JWT, but the old JWT will still pass verification! This can become a serious problem if a hacker gets ahold of a user’s password. To close the loop on this issue, we can make a clever little adjustment to our UserModel database model to include a version parameter, which will be a counter that increments with each new password for the user. We’ll incorporate version into our JWT so only the newest JWT will pass our security.

2018-06-10

IBM developerWorks

算法

随机数生成器

使您的软件运行起来
摆弄数字
真正安全的软件需要精确的随机数生成器
https://www.ibm.com/developerworks/cn/security/playing/index.html

java

Java 编程的动态性，第 1 部分
类和类装入
研究类以及 JVM 装入类时所发生的情况
https://www.ibm.com/developerworks/cn/java/j-dyn0429/

class类文件
cafe babe 任何 Java 二进制类（甚至是文件系统中没有出现的类）都需要以这四个字节作为开始
0000 次版本 0
002e 主版本 46
001a 常量池中项的总数
后面是实际的常量池数据常量池往往占到二进制类大小的一半或更多，但平均下来可能要少一些。

方法的可执行代码用 JVM 的指令形式表示该代码，一般称为字节码
构成类文件可执行部分的字节码实际上是针对特定类型的计算机 ― JVM ― 的机器码
JVM被称为虚拟机，因为它被设计成用软件来实现，而不是用硬件来实现。每个用于运行 Java 平台应用程序的 JVM 都是围绕该机器的实现而被构建的。
JVM使用堆栈体系结构，这意味着在使用指令操作数之前要先将它们装入内部堆栈。
早期的（第一代）JVM 基本上是虚拟机字节码的解释器。这些虚拟机实际上的确相对简单，但存在严重的性能问题 ― 解释代码的时间总是会比执行本机代码的时间长。
第二代 JVM 添加了即时（just-in-time，JIT）转换。在第一次执行 Java 字节码之前，JIT 技术将它编译成本机代码，从而对于重复执行提供了更好的性能。
当代 JVM 的性能甚至还要好得多，因为使用了适应性技术来监控程序的执行并有选择地优化频繁使用的代码。

JAR 只是类文件的容器

增加环境变量 JAVA_OPTS -verbose 可以查看类加载过程

C 和 C++ 这些编译成本机代码的语言通常在编译完源代码之后需要链接这个步骤

使用 Java 语言，由编译器生成的类在被装入到 JVM 之前通常保持原状

链接类不是一个独立步骤，它是在 JVM 将这些类装入到内存时所执行作业的一部分

能装入独立的类集合这一灵活性是 Java 平台的一个重要特性。尽管这个特性很有用，但是它在某些情况中会产生混淆。

一个令人混淆的方面是处理 JVM 类路径这样的老问题。

使用多个类装入器还可能引起其它类型的混淆。身份危机（class identity crisis）

JDK5.0以后不需要配classpath了，只要把path配好就行

敏捷开发中高质量 Java 代码开发实践
https://www.ibm.com/developerworks/cn/java/j-lo-agile/

步骤一：统一编码规范、代码样式
步骤二：静态代码分析
步骤三：单元测试
步骤四：持续集成（Continuous Integration）
步骤五：代码评审和重构（Code Review）

使用原汁原味的 Java 语言
非 Java 原生程序员的语言流畅性
https://www.ibm.com/developerworks/cn/java/j-noaccent.html

Java 的惯例中 main()方法的参数名为 args，而不是 argv：public static void main(String[] args)

深入探讨 Java 类加载器
https://www.ibm.com/developerworks/cn/java/j-lo-classloader/

常用 Java 静态代码分析工具的分析与比较
https://www.ibm.com/developerworks/cn/java/j-lo-statictest-tools/

使用 Java 开源工具建立一个灵活的搜索引擎
揭示开源的力量
https://www.ibm.com/developerworks/cn/java/j-lo-sefrmk/

几种任务调度的 Java 实现方法与比较
https://www.ibm.com/developerworks/cn/java/j-lo-taskschedule/index.html

用 Quartz 进行作业调度
Quartz API 采用多面方式在 Java 应用程序中进行任务调度
https://www.ibm.com/developerworks/cn/java/j-quartz/

在 Web 项目中应用 Apache Shiro
https://www.ibm.com/developerworks/cn/java/j-lo-shiro/

从虚拟机视角谈 Java 应用性能优化
https://www.ibm.com/developerworks/cn/java/j-lo-jvm-perf/

使用 VisualVM 进行性能分析及调优
https://www.ibm.com/developerworks/cn/java/j-lo-visualvm/

优化 Java 垃圾收集器改进系统性能
https://www.ibm.com/developerworks/cn/java/j-lo-optimize-gc/

Java的内存泄漏
https://www.ibm.com/developerworks/cn/java/l-JavaMemoryLeak/

Java 性能优化之 String 篇
https://www.ibm.com/developerworks/cn/java/j-lo-optmizestring/

Java Web 高性能开发，第 1 部分
前端的高性能
https://www.ibm.com/developerworks/cn/java/j-lo-javawebhiperf1/

您不知道的 5 件事……
JVM 命令行标志
调优 JVM 性能和 Java 运行时
https://www.ibm.com/developerworks/cn/java/j-5things11/index.html

Java.next, Common ground in Groovy, Scala, and Clojure, Part 1
Explore how these next-generation JVM languages handle operator overloading
https://www.ibm.com/developerworks/java/library/j-jn2/index.html

Java.next, Common ground in Groovy, Scala, and Clojure, Part 3
Rethinking exceptions, expressions, and emptiness
https://www.ibm.com/developerworks/java/library/j-jn4/index.html

使用JMeter进行性能测试
https://www.ibm.com/developerworks/cn/java/l-jmeter/

使用 JMeter 完成常用的压力测试
https://www.ibm.com/developerworks/cn/opensource/os-pressiontest/

启用动态 HTTP 压缩
在各种 Web 服务器上通过动态压缩节省带宽
https://www.ibm.com/developerworks/cn/web/wa-httpiis/

最佳实践：更好的设计你的 REST API
https://www.ibm.com/developerworks/cn/web/1103_chenyan_restapi/

NIO 入门
https://www.ibm.com/developerworks/cn/education/java/j-nio/j-nio.html

Merlin 给 Java 平台带来了非阻塞 I/O
新增的功能大幅降低了线程开销
https://www.ibm.com/developerworks/cn/java/j-javaio/

深入分析 Java 中的中文编码问题
https://www.ibm.com/developerworks/cn/java/j-lo-chinesecoding/

Java SSL/TLS 安全通讯协议介绍
Java 的安全通讯
https://www.ibm.com/developerworks/cn/java/j-lo-ssltls/

Java 安全套接字编程以及 keytool 使用最佳实践
https://www.ibm.com/developerworks/cn/java/j-lo-socketkeytool/

开源规则流引擎实践
https://www.ibm.com/developerworks/cn/opensource/os-drools/index.html

使用 Drools 规则引擎实现业务逻辑

如果你的业务场景中有很多复杂的业务逻辑/业务策略，而这些业务策略又经常发生变化，那么你就可以引入规则引擎技术。

开发 Spring Redis 应用程序
使用 Redis 作为数据存储来构建基于 Spring 的应用程序
https://www.ibm.com/developerworks/cn/java/os-springredis/index.html

Java 编程中的 OAuth 2.0 客户端，第 1 部分
资源所有者密码凭据授权
https://www.ibm.com/developerworks/cn/java/se-oauthjavapt1/index.html

Java 编程中的 OAuth 2.0 客户端，第 2 部分
客户端凭据授权
https://www.ibm.com/developerworks/cn/java/se-oauthjavapt2/index.html

Java 编程中的 OAuth 2.0 客户端，第 3 部分
认证码授权
https://www.ibm.com/developerworks/cn/java/se-oauthjavapt3/index.html

Java 开发 2.0
现实世界中的 Redis
Redis 如何在包含大量读取操作的应用程序中战胜 memcached
https://www.ibm.com/developerworks/cn/java/j-javadev2-22/

全面分析 Spring 的编程式事务管理及声明式事务管理
https://www.ibm.com/developerworks/cn/education/opensource/os-cn-spring-trans/

Spring 事务管理高级应用难点剖析
第 1 部分
https://www.ibm.com/developerworks/cn/java/j-lo-spring-ts1/index.html

Spring 事务管理高级应用难点剖析
第 2 部分
https://www.ibm.com/developerworks/cn/java/j-lo-spring-ts2/

Spring 事务管理高级应用难点剖析
第 3 部分
https://www.ibm.com/developerworks/cn/java/j-lo-spring-ts3/index.html

使用 Spring 进行单元测试
https://www.ibm.com/developerworks/cn/java/j-lo-springunitest/

使用 Apache JMeter 测试基于云的应用程序
学习使用 JMeter 进行 RESTful API 测试的有效技术和最佳实践
https://www.ibm.com/developerworks/cn/cloud/library/cl-jmeter-restful/

让开发自动化
用 Eclipse 插件提高代码质量
在 Eclipse 中使用 5 个有用的插件来自动化代码质量分析
https://www.ibm.com/developerworks/cn/java/j-ap01117/

常用 Java Profiling 工具的分析与比较
https://www.ibm.com/developerworks/cn/java/j-lo-profiling/

Java Web 高性能开发，第 2 部分
前端的高性能
https://www.ibm.com/developerworks/cn/java/j-lo-javawebhiperf2/

在 Java 应用程序中使用 Elasticsearch
高性能 RESTful 搜索引擎和文档存储快速入门指南
https://www.ibm.com/developerworks/cn/java/j-use-elasticsearch-java-apps/index.html

Java 应用性能调优实践
让 Java 应用运行更快：性能调优工具及实践
https://www.ibm.com/developerworks/cn/java/j-lo-performance-tuning-practice/

通过零拷贝实现有效数据传输
零拷贝，零开销
https://www.ibm.com/developerworks/cn/java/j-zerocopy/

Java 性能分析工具 , 第 1 部分
操作系统工具
https://www.ibm.com/developerworks/cn/java/j-lo-performance-analysissy-tools/

Java 性能测试的四项原则
https://www.ibm.com/developerworks/cn/java/j-lo-java-performance-testing/

Groovy 使 Spring 更出色，第 1 部分: 集成的基础知识

Java 8 Annotation 新特性在软件质量和开发效率方面的提升

使用 Groovy 构建 DSL

Groovy：Java 程序员的 DSL

SQL

SQL 语句性能调优
初级篇 —— 简单查询语句的调优
https://www.ibm.com/developerworks/cn/data/library/techarticles/dm-1002limh/index.html

SQL 在常用报表业务中的归并、转换与信息汇总中的应用技巧
https://www.ibm.com/developerworks/cn/data/library/techarticles/dm-1008yangxy/

JavaScript

Understand memory leaks in JavaScript applications
Detect and address memory issues
https://www.ibm.com/developerworks/library/wa-jsmemory/index.html

拥抱原型面向对象编程
https://www.ibm.com/developerworks/cn/web/wa-protoop/index.html

浅谈 JavaScript 编程语言的编码规范
https://www.ibm.com/developerworks/cn/web/1008_wangdd_jscodingrule/

使用 Chrome 开发者工具进行 JavaScript 问题定位与调试
https://www.ibm.com/developerworks/cn/web/1410_wangcy_chromejs/index.html

JavaScript 中的类

用 Maven 做项目构建

POM 即 Project Object Module，项目对象模型，在 pom.xml 文件中定义了项目的基本信息、源代码、配置文件、开发者的信息和角色、问题追踪系统、组织信息、项目授权、项目的 url、以及构建项目所用的插件，依赖继承关系。

Maven 本质上是一个插件框架，它的核心并不执行任何具体的构建任务，仅仅定义了抽象的生命周期，所有这些任务都交给插件来完成的。每个插件都能完成至少一个任务，每个任务即是一个功能，将这些功能应用在构建过程的不同生命周期中。这样既能保证拿来即用，又能保证 maven 本身的繁杂和冗余。

可以用去除这种依赖的传递

可以在当前的 POM 文件中使用元素声明排除依赖，exclusions 可以包含一个或者多个 exclusion 子元素，因此可以排除一个或者多个传递性依赖。

Nexus是Maven仓库管理器，用来搭建一个本地仓库服务器，这样做的好处是便于管理，节省网络资源，速度快，还有一个非常有用的功能就是可以通过项目的SNAPSHOT版本管理，来进行模块间的高效依赖开发

ES6

新 JavaScript 中的变量声明等功能

React

React：创建可维护、高性能的 UI 组件
使用 React JavaScript 库创建可维护的 Web UI，超越浏览器 DOM
https://www.ibm.com/developerworks/cn/web/wa-react-intro/index.html

React 介绍及实践教程
https://www.ibm.com/developerworks/cn/web/1509_dongyue_react/

redux

Redux 简介

状态管理是软件开发的最困难方面之一，这使得状态管理错误成为了几乎所有 bug 的源头。

Redux，这是一个针对 JavaScript 应用程序的可预测的状态容器。
Redux 不仅有助于状态管理，还使得实现一些高级特性变得很简单，比如无限撤销/重做和实时编辑时间旅行 (live-editing time travel)。

尽管 Redux 来自 React 社区，但它并不依赖于 React。

Redux 是 Facebook 的 Flux 架构的一种简化实现。

Flux 在本质上采用了模型-视图-控制器 (MVC) 的结构

Redux 有 3 条原则：

应用程序状态存储在单个对象中。
应用程序状态不可变，只能通过描述状态更改的操作彻底替换。
缩减程序根据当前状态和某个操作来创建下一个状态。

Redux 简介

结合使用 Redux 和 React

Unix

对话 UNIX，第 4 部分
UNIX 所有权和权限管理
共享信息
https://www.ibm.com/developerworks/cn/aix/library/au-speakingunix4/index.html

UNIX 文件的权限位表示了三类用户（您本人、您的一个组和其他用户）的某一种特定的权限
10 个字符组成的序列
每个字符都是一个开/关设置或位

起始位表示该文件是否为目录（通常，起始位表示该文件是否为特殊文件。如果该文件是特殊文件，起始字符 d 表示目录、l 表示符号链接，等等）。这个设置是无法改变的。

接下来的三位（用蓝色表示的）分别表示您对该文件的读、写和执行权限。您可以禁用写权限位，例如要防止删除文件。（是的，要删除一个文件，您需要写权限。）

接下来的三位（用绿色表示的）表示组对该文件的读、写和执行权限。

最后的三位（用橙色表示的）表示所有其他用户（即除了您自己以及您的组中的成员之外的所有用户）的权限。

您可以使用 chmod（更改模式 change mode）命令修改相应的权限（除了目录位之外）。您可以使用 chgrp（更改组 change group）命令来修改文件所属的组。（超级用户 root 也可以使用 chown 或 change owner 命令来更改文件所有权。）

find . -type f -print | sort | uniq

您可以使用符号 ~（波浪符号）引用您的 home 目录。您还可以使用 $HOME 环境变量引用您的 home 目录

许多程序可以从一个名为 .netrc（读做 net-r-c）的文件中读取您的凭据，该文件通常位于 ~/.netrc 目录中。

Linux 新用户的基本任务
Linux 安装好后，下一步该做什么？
https://www.ibm.com/developerworks/cn/linux/tutorials/l-basics/

学习 Linux，101
LPIC-1 路线图
关于 LPIC-1 考试准备的 developerWorks 文章指南
https://www.ibm.com/developerworks/cn/linux/l-lpic1-v3-map/

学习 Linux，101
创建和更改硬链接和符号链接
为同一文件使用多个名称
https://www.ibm.com/developerworks/cn/linux/l-lpic1-v3-104-6/

学习 Linux，101
管理文件权限和所有权
在您的文件上设置正确的安全性
https://www.ibm.com/developerworks/cn/linux/l-lpic1-v3-104-5/index.html

学习 Linux，101
RPM 和 YUM 包管理
添加新软件并及时更新系统
https://www.ibm.com/developerworks/cn/linux/l-lpic1-v3-102-5/

Bash 实例，第一部分
Bourne again shell (bash) 基本编程
https://www.ibm.com/developerworks/cn/linux/shell/bash/bash-1/

Bash 实例，第 2 部分
更多的 bash 基本编程
https://www.ibm.com/developerworks/cn/linux/shell/bash/bash-2/

Bash 实例，第 3 部分
探讨 ebuild 系统
https://www.ibm.com/developerworks/cn/linux/shell/bash/bash-3/

系统管理员工具包
充分利用 bash
https://www.ibm.com/developerworks/cn/aix/library/au-satbash.html

LPI 102 考试准备，主题 109
Shell、脚本、编程和编译
初级管理（LPIC-1）主题 109
https://www.ibm.com/developerworks/cn/education/linux/l-lpic1109/index.html

Linux 编程和系统管理新手入门
https://www.ibm.com/developerworks/cn/linux/newto/index.html

Windows 到 Linux 之旅: 系列文章概述
指引开发者走向 Linux 的路线图
https://www.ibm.com/developerworks/cn/linux/l-roadmap/index.html

Windows 到 Linux 之旅: 第 4 部分. 用户管理

Windows 到 Linux 之旅: 第 6 部分. 使用分区和文件系统

数据库

超越 MySQL
对流行数据库进行分支
https://www.ibm.com/developerworks/cn/opensource/os-beyondmysql/

LAMP 系统性能调优，第 3 部分
MySQL 服务器调优
利用服务器的几个调优技巧，让 MySQL 服务器飞速运行
https://www.ibm.com/developerworks/cn/linux/l-tune-lamp-3.html

Web

响应式 Web 设计技巧
https://www.ibm.com/developerworks/cn/web/1506_zhangqun_responsiveweb/

利用 Sass 改善 CSS 预处理

Syntactically awesome stylesheets (Sass) 是一种元语言和层叠式样式表 (CSS) 预处理程序

Sass 主要使用 Ruby 来实现

html5

使用 HTML 5 创建移动 Web 应用程序

第 1 部分: 联合使用 HTML 5、地理定位 API 和 Web 服务来创建移动混搭程序

第 2 部分: 使用 HTML 5 开启移动 Web 应用程序的本地存储

localStorage API

第 3 部分: 使用 HTML 5 支持移动 Web 应用程序离线工作

第 4 部分: 使用 Web Workers 来加速您的移动 Web 应用程序

Web Worker 规范

从 Android 2.0 开始，Android 浏览器就拥有了对 HTML 5 Web Worker 规范的全面支持。

第 5 部分: 使用 HTML 5 开发新的可视化 UI 特性

所有基于 Webkit 的浏览器都能实现 Canvas 并极大地优化其性能。

工具类

ImageMagick 魔咒
面向用户和程序员等受众的图像处理
https://www.ibm.com/developerworks/cn/opensource/os-imagemagick/index.html

其它

利用 squid 反向代理提高网站性能
https://www.ibm.com/developerworks/cn/linux/l-cn-squid/

MQ 遥测传输 (MQTT) V3.1 协议规范
https://www.ibm.com/developerworks/cn/webservices/ws-mqtt/index.html

使用 Nginx 提升网站访问速度
https://www.ibm.com/developerworks/cn/web/wa-lo-nginx/

管理移动云套接字连接
云提供商如何管理移动应用程序与云之间的连接
https://www.ibm.com/developerworks/cn/cloud/library/cl-mobilesockconnect/

配置 Tomcat 和 Wireshark 来获取并解码 SSL 通信
调试安全通信
https://www.ibm.com/developerworks/cn/web/tutorials/wa-tomcat/

使用 OpenSSL API 进行安全编程
创建基本的安全连接和非安全连接
https://www.ibm.com/developerworks/cn/linux/l-openssl.html

利用物联网 (IoT)
探索 IoT 的 7 个重要概念和开始使用它的 4 个步骤
https://www.ibm.com/developerworks/cn/iot/iot-key-concepts/index.html

了解 IT 即流程
如何自动化企业中的 IT 操作
https://www.ibm.com/developerworks/cn/websphere/techjournal/1510_brown-trs/1510_brown.html

使用访问令牌保护微服务

量子计算

量子计算入门
棘手问题的简便解法指南
https://www.ibm.com/developerworks/cn/linux/other/quant/

LLVM

使用 LLVM 框架创建一个工作编译器，第 1 部分

使用 LLVM 框架创建有效的编译器，第 2 部分

LLVM 拥有自己的前端：名为 clang 的一种工具（恰如其分）。Clang 是一种功能强大的 C/C++/Objective-C 编译器，其编译速度可以媲美甚至超过 GNU Compiler Collection (GCC) 工具（参见参考资料中的链接，获取更多信息）。更重要的是，clang 拥有一个可修改的代码基，可以轻松实现定制扩展。

blockchain

区块链技术基础：商业账本简介

区块链技术基础：术语和用例

Docker

Docker：带给现代开发人员的福利

Docker 就像是用于 DevOps 的一把瑞士军刀，这一点已得到充分证明。但 Docker 托管的应用程序容器的用途不仅是在云中部署服务器。Docker 容器还可以在许多常见的开发场景中帮助开发和显著提高生产力。

2018-06-10

quotes

The gap between the best software engineering practice and the average practice is very wide—perhaps wider than in any other engineering discipline. A tool that disseminates good practice would be important. — Fred Brooks

The laws of nature are but the mathematical thoughts of God. — Euclid

“Stop being so negative, Steven!”, “Why do you always assume the worst?”, “You’re such a ‘glass half empty’ person, Steven.”

我能召唤遥远的精灵。
那又怎么样，我也可以，谁都可以，问题是你真的召唤的时候，它们会来吗？ - 莎士比亚，《亨利四世》，第一部分

I can call spirits from the vasty deep.
Why, so can I, or so can any man; but will they come when you do call for them? - SHAKESPEARE, KING HENRY IV, Part I

GLENDOWER: I can call spirits from the vasty deep.
HOTSPUR: Why, so can I, or so can any man; But will they come when you do call for them?

William Shakespeare, King Henry IV, Part 1

他过去所做的许诺，是非凡的；
而他今天的执行，则什么也不是。
莎士比亚，《亨利八世》

只能根据过去判断将来。 - 帕特里克·亨利
然而永远无法根据过去规划将来。 - 埃德蒙·伯克
I know no way of judging the future but by the past. - PATRICK HENRY
You can never plan the future by the past. - EDMUND BURKE

普遍的做法是，选择一种方法，试试看；如果失败了，没关系，再试试别的。不管怎么样，重要的是先去尝试。 - 富兰克林 D. 罗斯福
It is common sense to take a method and try it. If it fails, admit it frankly and try another. But above all, try something. - FRANKLIN D. ROOSEVELT

Donald Knuth 曾经指出，“提前优化是万恶之源”。
“premature optimization is the root of all evil,” as Donald Knuth once put it

Cliff Click expressed the same sentiment this way:
Premature optimization is the root of all evil is more true today than ever before.

Hope for the best and prepare for the worst

Fear not the future ,Weep not for the past

Men are judged by what they do

There is no time like the present

We are all slaves of opinion

Practice is the best master

The language of truth is simple

A man must take the consequence of his own deeds

Great hopes makes great men

Life is short and time is swift

Example is better than precept

Practice what you preach

Practice makes perfect

Easier said than done

It is never too late to mend

Look not too high, lest something fall into your eye.

Plain living and high thinking

A good heart conquers ill fortune

A little body often harbors a great soul

2018-06-09

期刊摘句

你以为买到的是“知识”，其实只是“知道”。你以为买到的是“掌握”，其实只是囤积了一堆“知道”。 —— 学者方绍伟谈网络时代的“知识囤积症”

囤书如山倒，读书如抽丝，我早已经囤下后半辈子都读不完的书，但出于占有欲，我还是不断在买书。（摘自《读者》2018年08期）

一个人好像是一个分数，他的实际才能好比分子，而他对自己的估价好比分母，分母越大则分数值愈小。（托尔斯泰《人生论》）

HALT(hungry, angry, lonely, tired)

手中事和身边人。 —— 对一个人的价值最准确的考量标准

人工智能时代对人类最大的威胁是，它让我们将虚拟社群的联系与真实事物混为一谈。 —— 哈佛大学教授桑德尔谈技术对人类社会的改变

盯住领域里最牛的那几个人，他们就是方向。— 杨振宁

2018-06-09

Linux常用知识点

命令

最常用

man 帮助（按q退出man）
ls
pwd 输出工作目录
cd
mkdir
find 和 locate
cp
mv 改名、移动
more
kill 使用ps进程ID，kill进程
sudo
passwd 更改密码

sudo su

查看日志：tail -n 100 catalina.out

复制文件：
sudo cp kaopurServer.war /opt/apache-tomcat-8.0.24/webapps/

查看目录
ll

cat /etc/passwd

cat -n song.txt

给sh脚本增加执行权限：chmod +x yourshfile.sh

mkdir kaopurServer

cd kaopurServer

tar -zxvf ../kaopurServer.tar.gz

sudo \cp -rf kaopurServer/* /opt/apache-tomcat-8.0.24/webapps/kaopurServer

rm -f index.jsp

rm -rf WEB-INF/

如此才会覆盖：
sudo \cp -rf kaopurServer/* /opt/apache-tomcat-8.0.24/webapps/kaopurServer

sudo tar -zxf /home/hl/apache-activemq-5.9.1-bin.tar.gz

cat activemq.xml

linux下载文件：
curl -O http://mirrors.hust.edu.cn/apache/tomcat/tomcat-8/v8.0.28/bin/apache-tomcat-8.0.28.tar.gz

curl -O -L http://dev.mysql.com/get/Downloads/MySQL-5.6/mysql-5.6.27.tar.gz

xshell中文乱码：修改Terminal的字符集

$ ps -ef|grep tfs

curl -o emqttd-centos64-0.13.0-beta-20151108.zip -L http://emqtt.io/downloads/centos

cat /etc/redhat-release

linux常用命令
在 Linux 中用的是正斜杠 (/)，而不是您所熟悉的反斜杠 ()。反斜杠也用到了，但只是用来说明命令需要换行继续，这样可以提高比较长的命令的可读性。

ls -l 以长格式列出文件，包括文件大小、日期和时间、属性
ls -t 对文件以时间排序
ls -S 对文件以大小排序
ls -r 与一个排序开关组合起来使用，逆序排列。 ls -t 将最新的文件显示在列表的顶部。 ls -t 将最新的文件显示在底部。
ls -h 易读格式。使用 k、M、G 等来标识文件的大小，而不是以字节为单位。
ls -a 显示目录中所有的文件，包括隐藏文件

cp -R 递归地复制文件；当需要复制整个目录时会用到
cp -f 强制复制并覆盖已有的文件，不询问用户
cp -l 链接文件，而不是复制

使用 mv 命令来移动和重命名文件。这个命令的工作方式基本上与 DOS 中的 move 命令一样，不过它可以移动整个目录结构及所有文件。

cat
使用 cat 命令来查看文件的内容。它相当于 DOS 中的 type 命令。它将把文件的内容转储到另一个文件、屏幕或者其他命令。 cat 是concatenate 的简写，还可以将一系列的文件合并为一个大文件。

more
使用命令 more 可以以分页的方式查看文件。它基本上与 DOS 中的 more 命令相同。

less
less 命令也是用来查看文件，但是它支持上下滚屏以及在文档中进行文本搜索。

man
使用 man 命令来查看命令的文档。man 是 manual 的缩写。几乎每一个命令都有相应的文档。要深入了解 man ，请输入以下命令：

man man

info
info 命令与 man 命令类似，不过它提供了超链接文本，可以更方便地浏览文档。

curl -O -L http://dev.mysql.com/get/Downloads/MySQL-5.6/mysql-5.6.27.tar.gz

md5sum mysql-5.6.27.tar.gz

md5sum apache-tomcat-8.0.28.tar.gz

sudo tar -zxvf ~/apache-tomcat-8.0.28.tar.gz

sudo rm -r apache-tomcat-8.0.28/

/usr/apache-tomcat-8.0.28/webapps>sudo rm -r examples/

/usr>sudo rm -fr emqttd/

/home/hzg>sudo unzip emqttd-centos64-0.13.0-beta-20151108.zip -d /usr/

/usr/emqttd/bin>sudo ./emqttd console

/usr/emqttd/bin>./emqttd_ctl status

/opt/apache-tomcat-8.0.28/bin>ps -ef | grep tomcat

停止tomcat：
kill -9 2250

查看tomcat日志
/opt/apache-tomcat-8.0.28/logs>tail -n 50 catalina.out

curl -O -L http://download.redis.io/releases/redis-3.0.5.tar.gz

/home/hzg>sudo tar zxf redis-3.0.5.tar.gz -C /opt/

redis的java client
Jedis
lettuce
Redisson

/home/hzg>netstat -tnl | grep 3306

[root@instance-dqg4v0wr-3 ~]# du -sh
36K .

more /etc/passwd

lscpu

free -m

使用 su 或者 sudo -s 命令变为另一个用户
可以使用 whoami 命令来检查您当前有效的 id
可以使用 groups 命令找出您在什么组中

Linux 中的所有用户都存放于 /etc/passwd 文件中。您可以使用 more 命令来分页查看这个文件：
more /etc/passwd

who
功能：列出当前系统注册的用户
$who am i 列出当前系统使用者身份

ps
功能：显示后台进程的有关信息。单独使用ps将显示由
当前终端启动的后台进程的PID、终端号、进程已执行时间以及启动该进程的命令
语法：ps -options
参数说明：
-e：显示系统内当前运行的所有后台进程
-f：除ps所提供的信息外，还显示用户名、PPID（父进程ID）及启动时间
-l：除ps所提供的信息外，还显示 User ID, PPID 和进程优先级

kill
功能：杀死后台进程
语法：kill -num PID

find
功能：在一个或多个目录中查找符合指定条件的文件，
显示文件名或对这些文件进行特定的操作
语法：find path expression

find . –name ‘unix’ –print
find . –name ‘m*’ –exec ls –l {} ;
find . -perm 644 -mtime +4 –print

grep
功能：在文件或标准输入中搜索与指定格式相匹配的行
语法：grep [options] pattern [file1 file 2..]
grep –v mail .profile
grep “^a[0-9]z$” filename
grep a websm.log

vi

：w ：保存当前文件
：x：保存当前文件并退出
：q：退出vi
:q! 放弃所做修改直接退出到shell
:q 不退出
ZZ / :x 如果需要保存则保存，之后退出到shell
:w newfile / :w!
:wq 先保存文件，再退出到shell
回车后进行命令模式
在命令模式按a（光标之后）/ A（光标所在行的最后） / i（光标处）/I（光标所在行的开头） / o / O ，进入文本输入模式
在文本输入模式下，按Esc，回到命令模式
末行模式，Ex转义模式：在命令模式下按:进行末行模式，末行命令执行后自动回到命令模式

插入文本类命令

i ：在光标前
I ：在当前行首
a：光标后
r：替换当前字符

删除命令

x或X：删除一个字符，x删除光标后的，而X删除光标前的
ndd：删除当前行及其后n-1行
dd 删除当前行

搜索及替换命令

/pattern：从光标开始处向文件尾搜索pattern
?pattern：从光标开始处向文件首搜索pattern
:g/p1/s//p2/g：将文件中所有p1均用p2替换

2018-06-09

P vs NP Problem

If it is easy to check that a solution to a problem is correct, is it also easy to solve the problem? This is the essence of the P vs NP question. Typical of the NP problems is that of the Hamiltonian Path Problem: given N cities to visit (by car), how can one do this without visiting a city twice? If you give me a solution, I can easily check that it is correct. But I cannot so easily (given the methods I know) find a solution.

Suppose that you are organizing housing accommodations for a group of four hundred university students. Space is limited and only one hundred of the students will receive places in the dormitory. To complicate matters, the Dean has provided you with a list of pairs of incompatible students, and requested that no pair from this list appear in your final choice. This is an example of what computer scientists call an NP-problem, since it is easy to check if a given choice of one hundred students proposed by a coworker is satisfactory (i.e., no pair taken from your coworker’s list also appears on the list from the Dean’s office), however the task of generating such a list from scratch seems to be so hard as to be completely impractical. Indeed, the total number of ways of choosing one hundred students from the four hundred applicants is greater than the number of atoms in the known universe! Thus no future civilization could ever hope to build a supercomputer capable of solving the problem by brute force; that is, by checking every possible combination of 100 students. However, this apparent difficulty may only reflect the lack of ingenuity of your programmer. In fact, one of the outstanding problems in computer science is determining whether questions exist whose answer can be quickly checked, but which require an impossibly long time to solve by any direct procedure. Problems like the one listed above certainly seem to be of this kind, but so far no one has managed to prove that any of them really are so hard as they appear, i.e., that there really is no feasible way to generate an answer with the help of a computer. Stephen Cook and Leonid Levin formulated the P (i.e., easy to find) versus NP (i.e., easy to check) problem independently in 1971.

Image credit: on the left, Stephen Cook by Jiří Janíček (cropped). CC BY-SA 3.0

Problem Statement. Does Ｐ = ＮＰ?

$ \mathcal{P} $ = {L | L = L(M) for some Turing machine M that runs in polynomial time}.

The notation $ \mathcal{NP} $ stands for “Nondeterministic Polynomial time”, since originally ＮＰ was defined in terms of nondeterministic machines (that is, machines that have more than one possible move from a given configuration).

To put it more briefly, $ \mathcal{P} $ is the set of easy decision problems. $ \mathcal{NP} $ is the class of decision problems for which it is easy to check the correctness of a claimed answer, with the aid of a little extra information. So we aren’t asking for a way to find a solution, but only to verify that an alleged solution really is correct.

In Ｐ are the problems where it’s easy to find a solution, and in ＮＰ are the problems where it’s easy to check a solution that may have been very tedious to find.

$\huge \mathbf{\mathbb{P}} \subset \mathbf{\mathbb{NP}} \tt{?}$

The crucial question related to Ｐ and ＮＰ is whether the subset relation is proper?

很显然的是Ｐ类都属于ＮＰ类（$ \displaystyle {\mathsf {P}}\subseteq {\mathsf {NP}} $），这样问题就变成：是否某些NP类问题（比如旅行推销员问题）不存在多项式时间过程算法? 问题难在如何证明这一点？如何从逻辑上排除旅行推销员问题存在多项式时间过程算法的可能性？这跟黎曼假设的严格数学证明要排除临界线外有复零点的可能性一样困难。

复杂性范畴之间的包含关系：

$\mathrm{LOGSPACE} \subseteq \mathbf{P} \subseteq \mathbf{NP} \subseteq \mathrm{PSPACE} $
$\mathrm{LOGSPACE} \subset \mathrm{PSPACE} $

LOGSPACE ⊆ P ⊆ NP ⊆ PSPACE，用简单的对角化论证法能够证明 LOGSPACE 是 PSPACE 的真子集，其余的包含关系是否为真包含关系？无人能够证明。

很多研究复杂性理论的专家都认为Ｐ≠ＮＰ，Scott Aaronson 从哲学角度发表了他的看法：“如果P = NP，那么我们就会处于一个截然不同的世界中，创造性飞跃将失去其难能可贵的价值，解决一个问题和认识到问题有解没什么分别。任何一个能欣赏交响乐的人都能成为莫扎特，任何一个能理解数学证明的人都能成为高斯…”。（If P = NP, then the world would be a profoundly different place than we usually assume it to be. There would be no special value in “creative leaps,” no fundamental gap between solving a problem and recognizing the solution once it’s found. Everyone who could appreciate a symphony would be Mozart; everyone who could follow a step-by-step argument would be Gauss…）。按 Stephen Cook 在白皮书中的说法，如果P = NP，那么机器就能给出克雷数学研究所七大难题的形式化证明，尽管证明会很繁琐很冗长。( If P = NP, …. For example, it would transform mathematics by allowing a computer to find a formal proof of any theorem that has a proof of reasonable length, since formal proofs can easily be recognized in polynomial time. Such theorems may well include all of the CMI prize problems. Although the formal proofs may not be initially intelligible to humans, the problem of finding intelligible proofs would be reduced to that of finding a recognition algorithm for intelligible proofs. Similar remarks apply to diverse creative human endeavors, such as designing airplane wings, creating physical theories, or even composing music. The question in each case is to what extent an efficient algorithm for recognizing a good result can be found. This is a fundamental problem in artificial intelligence, and one whose solution itself would be aided by the NP-solver by allowing easy testing of recognition theories. )

在克雷数学研究所的官方资料中，此问题由 Stephen Cook （创造性地提出ＮＰ-complete 概念并证明The satisfiability problem是NP-完全问题）作出权威解读。

数学元素

图灵机（Turing Machine）
可计算性
NP-完全：如果图论中的哈密顿回路有类似欧拉回路那样的多项式判定算法，则所有其它NP类问题也都能用多项式时间过程解决

ＮＰ-hard 问题

哈密顿回路判定 (Hamiltonian Circuit )
旅行推销员问题 (The Traveling Salesman problem)
背包问题 (The Bin Packing problem)
数独(Sudoku)

专家评论

Richard Karp: (Berkeley, unsure, P!=NP) My intuitive belief is that P is unequal to NP,but the only supporting arguments I can offer are the failure of all efforts to place specific NP-complete problems in P by constructing polynomial-time algorithms.I believe that the traditional proof techniques will not suffice. Something entirely novel will be required. My hunch is that the problem will be solved by a young researcher who is not encumbered by too much conventional wisdom about how to attack the problem.
Donald Knuth: (Retired from Stanford) It will be solved by either 2048 or 4096. I am currently somewhat pessimistic. The outcome will be the truly worst case scenario: namely that someone will prove “P=NP because there are only finitely many obstructions to the opposite hypothesis”; hence there will exists a polynomial time solution to SAT but we will never know its complexity!
Alexander Razborov: (Institute for Advanced Study) Well, this problem is (at the moment) very unique since we seem to be missing even the most basic understanding of the nature of its difficulty. Neither we currently have any ideas of what approach might turn out to be viable and lead us to the solution (or at least to a better understanding of the problem). All approaches tried so far probably (in some cases, provably) have failed. In this sense P=NP is different from many other major mathematical problems on which a gradual progress was being constantly done (sometimes for centuries) whereupon they yielded, either completely or partially. Perhaps, although, the key word in this difference is “century”, and the P=NP problem has simply not aged enough yet (by mathematical standards).
Bob Tarjan: (Princeton) In my view, there is no way to even make intelligent guesses about the answer to any of these questions. If I had to bet now, I would bet that P is not equal to NP. I estimate the half-life of this problem at 25 - 50 more years, but I wouldn’t bet on it being solved before 2100. Its solution will require unforeseen new techniques.
Avi Wigderson: (Institute of Advanced Study) I think this project is a bit premature. I think we know too little of what is relevant to even guess answers to your questions, certainly if “we” is replaced by “I.”The only thing I can definitely say, is that it is one of the most important and interesting questions ever asked by humans, and more people and resources should participate in filling up the holes that would allow better guesses of answers to your questions.
Andrew Yao（姚期智）: It’s hard to say when the question will be resolved. I don’t have even an educated guess. Probably the resolution is that P is not equal to NP. I think the mathematical techniques used will be beautiful.
Scott Aaronson: Look, this question of whether P=NP, what can I say? People like to describe it as “probably the central unsolved problem of theoretical computer science.” That’s a comical understatement. P vs. NP is one of the deepest questions that human beings have ever asked. And not only that: it’s one of the seven million-dollar prize problems of the Clay Math Institute! What an honor! Imagine: our mathematician friends have decided that P vs. NP is as important as the Hodge Conjecture, or even Navier-Stokes existence and smoothness! (Apparently they weren’t going to include it, until they asked around to make sure it was important enough.) Dude. One way to measure P vs. NP’s importance is this. If NP problems were feasible, then mathematical creativity could be automated. The ability to check a proof would entail the ability to find one. Every Apple II, every Commodore, would have the reasoning power of Archimedes or Gauss. So by just programming your computer and letting it run, presumably you could immediately solve not only P vs. NP, but also the other six Clay problems. (Or five, now that Poincaré is down.) Well, we certainly believe P≠NP. Indeed, we don’t even believe there’s a general way to solve NP problems that’s dramatically better than brute-force search through every possibility. The central challenge any P≠NP proof will have to overcome is to separate the NP problems that really are hard from the ones that merely look hard.

观点

P vs. NP 问题的解决可能有赖于大幅度创新的证明技术
- Cantor’s diagonal argument: a mathematical proof that there are infinite sets which cannot be put into one-to-one correspondence with the infinite set of natural numbers. Turing’s proof for the insolubility of the halting problem uses diagonal arguments as well.
- How Yuri Matiyasevitch & Martin Davis, Hilary Putnam, and Julia Robinson solved Hilbert’s tenth problem? Any instance of the halting problem can be encoded as a system of Diophantine equations, so there is no general algorithm for deciding whether Diophantine equations can be solved.
- Gödel numbering: Gödel’s incompleteness theorems
- Forcing (mathematics): first used by Paul Cohen in 1963, to prove the independence of the axiom of choice and the continuum hypothesis from Zermelo–Fraenkel set theory.
堵丁柱 & 葛可一的《计算复杂性导论》前言：
- 人们在七十年代开始对NP-完全问题的研究主要是横向发展，也就是以许多不同的计算模型来分析难解问题的本质。这些新的计算模型包括了平行计算模型、概率计算模型、布尔线路、判断树、平均复杂性、交互证明系统以及程式长度复杂性等等。对这些新的计算模型的研究一方面使我们对难解问题有了更深一层的认识，一方面也产生了一些预想不到的应用。最显著的一个例子就是计算密码学的革命性突破：基于 NP 问题的公钥密码体系。另一个有名的例子是线性规划的多项式时间解的发现。
- 到了八十年代中，对NP-完全问题的研究有了纵向的突破，在许多表面看来并不相关的计算模型之间发现了深刻的刻划关系。这些刻划关系不但解决了几个令人困扰多年的未解问题，同时也刺激了其它相关领域的发展。其中之一是对线路复杂性的研究发现了一些问题在某种有限制的线路模型中必有指数下界。这些结果使用了组合数学与概率方法等新的数学工具，并且解决了一个有名的有关多项式分层的未解问题。另一个更重大的结果是以概率可验证明对 NP 类的刻划。由此得出了许多组合优化问题近似解的NP-完全性，从而刺激了算法界对近似算法研究的新热潮。这个结果来自于对交互证明系统这个概念的扩展，并且使用了线性代数与编码理论等数学证明技巧。
1993年 Razborov 和 Rudich 证明的一个结果表明，给定一个特定的可信的假设，在某种意义下「自然」的证明不能解决 P vs NP 问题。这表明一些现在似乎最有希望的方法不太可能成功。随着更多这类的定理得到证明，该定理的可能证明有越来越多的陷阱要规避。
In 1994, Alexander Razborov and Steven Rudich discovered the natural proofs barrier, which explained why previous attempts to prove P ≠ NP had failed.
Razborov and Rudich then proved their main result: A natural proof of P ≠ NP would require a very comprehensive understanding of how easy-to-compute and hard-to-compute functions differ, and that knowledge could also fuel a fast algorithm for spotting easy-to-compute functions even if they’re superficially complicated. If complexity theorists had succeeded in a natural proof of P ≠ NP, they would have discovered a nearly infallible way to glance at an arbitrary truth table and determine whether the corresponding function had high or low circuit complexity — a much stronger and more general result than they had set out to prove.
The first attempts at determining the relationship between P and NP used an elegant trick called diagonalization that had been essential for other major results in computer science. But researchers soon realized that any diagonalization-based solution to the P versus NP problem would be self-contradictory. Researchers concluded that they’d need new techniques to make progress.

2018-06-08

Substring versus Subsequence

Substring : A pattern P is called a substring of Text T if the pattern appears in the Text in a continuous fashion.
Subsequence : A pattern P is called a subsequence of Text T if the pattern preserves the relative ordering of characters within the text T and it might not appear in a continuous fashion. e.g., the prime numbers are a subsequence of the positive integers.

Subsequence is a generalisation of substring, suffix, and prefix. Finding the longest string which is a subsequence of two or more strings is known as the longest common subsequence problem.

Example: The string “anna” is a subsequence of the string “banana”:

1
2
3

banana
 || ||
 an na

Substring

A substring of a string is a prefix of a suffix of the string, and equivalently a suffix of a prefix. If one string is a substring of another, it is also a subsequence, which is a more general concept.

Example: The string “ana” is a substring (and subsequence) of banana at two different offsets:

banana
 |||||
 ana||
   |||
   ana

2018-06-05

蘭亭集序

書法家王羲之所作

永和九年，岁在癸(guǐ)丑。暮春之初，会于会(kuài)稽山阴之兰亭，修禊(xì)事也。群贤毕至，少长(zhǎng)咸集。此地有崇山峻岭，茂林修竹，又有清流激湍，映带左右，引以为流觞(shāng)曲水，列坐其次。虽无丝竹管弦之盛，一觞一咏，亦足以畅叙幽情。

是日也，天朗气清，惠风和畅。仰观宇宙之大，俯察品类之盛。所以游目骋(chěng)怀，足以极视听之娱，信可乐也。

夫(fú)人之相与，俯仰一世。或取诸怀抱，悟言一室之内; 或因寄所托，放浪形骸之外。虽趣(qǔ)舍万殊，静躁不同，当其欣于所遇，暂得于己，快然自足，不知老之将至; 及其所之既倦，情随事迁，感慨系之矣。向之所欣，俯仰之间，已为陈迹，犹不能不以之兴怀，况修短随化，终期于尽!古人云：“死生亦大矣”，岂不痛哉!

每览昔人兴感之由，若合一契，未尝不临文嗟悼，不能喻之于怀。固知一死生为虚诞，齐彭殇(shāng)为妄作。后之视今，亦犹今之视昔，悲夫!故列叙时人，录其所述，虽世殊事异，所以兴怀，其致一也。后之览者，亦将有感于斯文。

由林语堂翻译的英文版

Preface to the Poems Collected from the Orchid Pavilion

by Lin Yutang

It is the ninth year of Yonghe (A.C.353), also known as the year of Guichou in terms of the Chinese lunar calendar.

On one of those late spring days, we gather at the Orchid Pavilion, which is located in Shanyin County, Kuaiji Prefecture, for dispelling bad luck and praying for good fortune.

The attendees of the gathering are all virtuous intellectuals, varying from young to old.

Endowed with great mountains and lofty peaks, Orchid Pavilion has flourishing branches and high bamboo bushes all around, together with a clear winding brook engirdled, which can thereby serve the guests by floating the wine glasses on top for their drinking.

Seated by the bank of brook, people will still regale themselves right by poetizing their mixed feelings and emotions with wine and songs, never mind the absence of melody from string and wind instruments.

It is such a wonderful day, with fresh air and mild breeze. Facing upwards to the blue sky, we behold the vast immensity of the universe; when bowing our heads towards the ground, we again satisfy ourselves with the diversity of species.

Thereby we can refresh our views and let free our souls, with luxuriant satisfaction done to both ears and eyes. How infinite the cheer is!

People keep coming and going, and life soon rushes to its end. Some people prefer to share their proud aspiration and lofty goals with close friends indoors, while some others choose to follow their interest and free their minds wherever and whenever they like.

May characters vary from person to person, or some would rather stay peaceful while others like to live restlessly, they will all become delighted and satisfied once they meet something pleasant, so cheerful that they get unaware of their imminent old age.

However, when they get tired of their old fancies that they’ve already experienced, and sentiment correspondingly accompanies the change of situation, all sorts of complicated feelings will well up in the heart, too.

Isn’t it thought-provoking that the happiness we used to enjoy passes by without leaving a single trace, let alone that the length of life is subject to the fate, and death is inevitable for anybody in the end?

Just as some ancient man once put it, “Death also deserves our attention, like what life does.”, so how can we restrain ourselves from grieving?

Every time I ponder about the reasons why our predecessors would produce works with such inenarrable emotions, I find there seem some similarities between our minds.

Yet I cannot help lamenting their literary masterpieces while I am struggling for the very cause in my innermost world. Now I come to realize that it has been ridiculous for me to equate death with life, long life with short life.

The descendents view us just the way we look at our predecessors, and how woeful it is! Hence I write down all the names of the attendees and put their poetry into record.

Conditions may go with the changes of time, but people’s emotions shall stay the same. I believe the following readers will still have much to mediate about life and death when appreciating this poetry anthology.

2018-06-03

General Service List

69975 the
39175 be
36432 of
28872 and
26800 a
26190 to
21338 in
20033 he
12458 have
11247 it
10790 that
9495 for
8555 they
8516 I
7289 with
7254 as
6976 not
6742 on
6164 she
5377 at
5307 by
5146 this
4931 we
4695 you
4389 do
4383 but
4371 from
4204 or
3560 which
3480 one
3062 would
3002 all
2903 will
2851 there
2793 say
2678 who
2378 make
2333 when
2218 can
2203 more
2199 if
2149 no
2132 man
2099 out
2035 other
1986 so
1965 what
1940 time
1895 up
1849 go
1816 about
1794 than
1790 into
1782 could
1773 state
1751 only
1698 new
1673 year
1618 some
1586 take
1577 come
1575 these
1531 know
1520 see
1512 use
1488 get
1430 like
1377 then
1361 first
1348 any
1315 work
1314 now
1307 may
1303 such
1270 give
1239 over
1225 think
1203 most
1179 even
1086 find
1077 day
1070 also
1070 after
1036 way
1030 many
1022 must
1021 look
1018 before
1018 great
1017 back
987 through
957 long
949 where
937 much
915 should
906 well
905 people
903 down
895 own
889 just
883 because
879 good
878 each
864 those
853 feel
853 seem
849 how
847 high
835 too
835 place
833 little
832 world
797 very
792 still
789 nation
784 hand
780 old
774 life
771 tell
768 write
768 become
761 here
755 show
745 house
731 both
730 between
723 need
719 mean
711 call
710 develop
707 under
705 last
704 right
703 move
702 thing
700 general
697 school
697 never
690 same
690 another
681 begin
680 while
678 number
672 part
668 turn
664 real
662 leave
660 might
654 want
645 point
639 form
639 off
638 child
634 few
632 small
629 since
627 against
614 ask
611 late
611 home
605 interest
605 large
601 person
600 end
596 open
590 public
589 follow
588 during
584 present
583 without
580 again
577 hold
568 govern
567 around
565 possible
564 head
563 consider
560 word
560 program
560 problem
552 however
552 lead
548 system
546 set
539 order
539 eye
538 plan
534 run
534 keep
534 face
534 fact
534 group
533 play
531 stand
529 increase
529 early
528 course
527 change
523 help
522 line
521 city
513 put
511 close
506 case
504 force
501 meet
501 once
501 water
498 upon
496 war
496 build
496 hear
496 light
495 unite
493 live
492 every
491 country
490 bring
490 center
489 let
488 side
487 try
486 provide
484 continue
482 name
481 certain
480 power
479 pay
473 result
473 question
471 study
468 woman
464 member
463 until
461 far
460 night
458 always
458 service
458 away
457 report
454 something
453 company
452 week
451 church
451 toward
451 start
449 social
445 room
443 figure
441 nature
440 though
438 young
437 less
434 enough
433 almost
432 read
426 include
424 president
423 nothing
419 yet
418 better
417 big
413 boy
412 cost
412 business
411 value
409 second
407 why
406 clear
405 expect
405 family
401 complete
401 act
401 sense
400 mind
399 experience
396 art
395 next
395 near
394 direct
393 car
393 law
387 industry
386 important
381 girl
379 god
378 several
377 matter
376 usual
373 rather
371 per
369 often
369 kind
369 among
368 white
365 reason
365 action
364 return
364 foot
360 care
360 simple
359 within
358 love
358 human
355 along
353 appear
353 doctor
353 believe
352 speak
351 active
351 student
350 month
349 drive
348 concern
348 best
348 door
346 hope
345 example
345 inform
344 body
344 ever
343 least
343 probable
343 understand
342 reach
340 effect
339 different
337 idea
337 whole
335 control
333 condition
333 field
333 pass
333 fall
332 note
332 special
332 talk
331 particular
330 today
329 measure
328 walk
328 teach
327 low
327 hour
326 type
326 carry
324 rate
324 remain
324 full
323 street
323 easy
323 although
321 record
321 sit
320 determine
315 level
313 local
312 sure
312 receive
311 thus
309 moment
308 spirit
308 train
308 college
307 religion
307 perhaps
306 music
306 grow
305 free
304 cause
302 serve
302 age
302 book
302 board
302 recent
301 sound
301 office
300 cut
299 step
297 class
297 true
297 history
296 position
296 above
295 strong
294 friend
293 necessary
292 add
292 court
291 deal
290 tax
289 support
286 party
286 whether
285 either
285 land
285 material
285 happen
285 education
284 death
284 agree
283 arm
282 mother
282 across
281 quite
281 anything
281 town
281 past
281 view
281 society
280 manage
280 answer
280 break
279 organize
277 half
276 fire
276 lose
275 money
275 stop
275 actual
274 already
274 effort
273 wait
273 department
273 able
272 political
271 learn
271 voice
269 air
269 together
269 shall
269 cover
269 common
268 subject
266 draw
265 short
265 wife
265 treat
263 limit
262 road
262 letter
260 color
260 behind
258 produce
258 send
258 term
257 total
256 university
254 rise
254 century
253 success
253 minute
251 remember
250 purpose
250 test
248 fight
247 watch
247 situation
246 south
246 ago
245 difference
245 stage
244 father
243 table
242 rest
242 bear
240 entire
240 market
240 prepare
240 explain
239 offer
239 plant
238 charge
238 ground
238 west
237 picture
237 hard
234 front
233 lie
232 modern
231 dark
230 surface
230 rule
230 regard
229 dance
229 peace
227 observe
227 future
227 wall
225 farm
225 claim
225 firm
223 operation
223 further
223 pressure
222 property
222 morning
222 amount
221 top
221 outside
221 piece
221 sometimes
220 beauty
220 trade
220 fear
220 demand
220 wonder
219 list
219 accept
218 judge
218 paint
217 mile
217 soon
215 responsible
214 allow
214 secretary
214 heart
213 union
213 slow
213 island
213 enter
213 drink
212 story
211 experiment
211 stay
210 paper
210 space
210 apply
209 decide
208 share
207 desire
207 spend
207 sign
206 therefore
206 various
206 visit
205 supply
205 officer
205 doubt
204 private
204 immediate collins merriam-webster
204 wish
204 contain
204 feed
204 raise
204 describe
203 ready
203 horse
202 son
202 exist
202 north
201 suggest
200 station
200 effective
199 food
199 deep
198 wide
197 alone
196 character
195 english
196 happy
196 critic collins merriam-webster
195 unit
195 product
195 respect
195 drop
195 nor
195 fill
194 cold
193 represent collins merriam-webster
193 sudden
192 basic
192 kill
191 fine
191 trouble
191 mark
191 single
190 press
189 heavy
189 attempt
189 origin collins merriam-webster
189 standard
188 everything
188 committee
188 moral
187 black
186 red
186 bad
186 earth
185 accord
185 else
185 mere
184 die
184 remark
184 basis
184 except
183 equal
183 east
183 event
183 employ
183 defense
183 smile
183 river
183 improve
182 game
181 detail
181 account
181 cent
181 sort
180 reduce
180 club
180 buy
180 attention
180 ship
179 decision
178 wear
178 inside
178 win
178 suppose
178 ride
177 operate
177 realize
177 sale
177 choose
177 park
177 square
176 vote
176 price
176 district
175 dead
175 foreign
175 window
175 beyond
174 direction
174 strike
174 instead
173 trial
173 practice
173 catch
172 opportunity
172 likely
170 recognize
170 permit
170 serious
170 attack
170 floor
168 association
168 spring
167 lot
167 stock
167 lack
167 hair
167 science
166 relation
166 profession
166 pattern
165 quick
164 medical
165 influence
165 occasion
165 machine
164 compare
163 husband
163 blue
163 international
162 fair
162 especially
162 indeed
162 imagine
162 surprise
162 average
161 official
161 temperature
161 difficult
160 sing
160 hit
160 tree
160 race
160 police
160 touch
159 relative
159 throw
159 quality
159 former
158 pull
157 chance
157 prove
157 argue
157 settle
156 growth
156 date
156 heat
155 save
155 performance
155 count
155 production
154 listen
152 main
154 pick
154 size
152 cool
152 army
152 patient
151 combine
151 summer
151 hall
151 slight
151 command
151 enjoy
151 length
150 proper
150 express
150 health
150 chief
149 evening
149 store
149 language
148 degree
148 lay
147 current
147 gun
147 dog
147 hotel
147 strange
147 separate
146 boat
146 fail
146 clean
146 dress
146 anyone
146 gain
146 pain
145 object
145 knowledge
145 depend
145 relate
145 below
144 dollar
144 advance
144 shape
144 arrange
144 population
144 yes
144 sell
144 mention
144 dry
144 check
144 poet
143 sleep
143 join
143 hot
143 bed
143 electric
143 dream
142 due
142 season
142 manner
142 fit
142 left
141 progress
141 neither
141 strength
140 notice
140 finish
140 opinion
140 bill
140 western
140 truth
138 wrong
138 travel
138 suit
137 bank
137 exact
137 honor
137 brother
136 quiet
136 marry
136 corner
135 handle
135 danger
135 hospital
135 pool
135 promise
135 blood
135 shoot
135 scene
134 literature
134 arrive
134 film
133 base
133 freedom
133 bar
133 maybe
133 hang
133 suffer
133 manufacture
132 frequent
132 rock
132 loss
131 burn
131 sun
131 audience
130 essential
130 glass
130 prevent
130 poem
130 poor
130 inch
129 song
129 skill
129 post
129 popular
129 radio
129 animal
128 conscious
128 worth
128 eat
128 election
128 faith
128 wave
128 murder
128 model
128 forget
127 extend
127 edge
127 distance
127 memory
127 recommend
126 division
126 staff
126 leg
126 discussion
126 address
126 fly
125 dependent
125 ball
125 shake
125 frame
125 extreme
124 engineer
124 thick
124 comfort
124 latter
124 camp
124 oil
124 discover
124 examine
123 difficulty
123 tooth
123 middle
123 choice
123 refer
123 enemy
123 practical
122 marriage
122 bridge
122 declare
122 lady
122 cross
122 daily
122 afternoon
121 attend
121 director
121 balance
121 wash
121 capital
120 speed
120 block
120 citizen
119 mouth
119 hill
118 green
118 please
118 motor
118 agency
118 encourage
118 governor
117 worry
117 affair
117 shoulder
117 bright
116 mass
116 sample
116 pretty
116 repeat
115 roll
115 push
115 trip
115 council
115 clothe
115 parent
115 forward
114 sharp
114 straight
113 gas
113 weight
113 discuss
113 fix
113 load
112 master
112 whatever
112 round
112 rapid
112 laugh
111 finger
111 spot
110 propose
110 shop
110 broad
110 replace
110 reply
110 extent
109 lock
109 employee
109 ahead
109 sight
109 spread
109 wind
109 approve
109 destroy
108 none
108 pound
108 fame
108 importance
107 reflect
107 advantage
107 match
107 regular
107 wage
107 refuse
107 existence
106 hardly
106 perform
106 title
105 tend
105 exercise
105 thin
105 coat
105 bit
105 mountain
105 youth
104 behavior
104 newspaper
104 secret
104 ability
104 sea
104 soft
104 justice
104 reasonable
104 circle
104 solid
104 page
103 weapon
103 fast
103 representative
103 search
103 pure
103 escape
102 crowd
102 stick
101 telephone
101 avoid
101 garden
101 favor
101 news
101 unless
100 dinner
100 someone
100 signal
100 yard
100 ideal
100 warm
100 miss
100 shelter
100 soldier
99 article
99 cry
99 captain
99 familiar
99 seat
99 guest
98 weak
98 excite
98 king
98 everyone
98 wine
97 hole
97 duty
97 beat
97 perfect
97 bottom
97 compose
97 battle
97 expense
97 cattle
96 flow
95 kitchen
95 dust
95 bottle
94 admit
94 tear
94 tire
94 expression
93 exception
93 application
93 belong
93 rich
93 failure
93 struggle
93 instrument
93 variety
93 narrow
92 theater
92 collection
92 rain
92 review
92 preserve
92 leadership
91 clay
91 daughter
91 fellow
91 swing
91 thank
90 library
90 fat
90 reserve
89 tour
89 nice
89 warn
89 ring
89 bitter
89 chair
89 yesterday
89 scientific
88 flower
88 wheel
88 solution
88 aim
88 gather
88 invite
88 moreover
88 fresh
88 forest
87 winter
87 box
87 belief
87 ordinary
87 impossible
87 print
87 gray
87 taste
87 lip
87 speech
87 reference
86 stain
86 connection
86 otherwise
86 stretch
86 knife
86 village
86 blow
85 mistake
85 sweet
85 shout
85 divide
85 guard
85 worse
85 exchange
85 rare
84 commercial
84 request
84 appoint
84 agent
83 dependence
83 bird
83 wild
83 motion
83 guess
83 neighbor
82 seed
82 fashion
82 loan
82 correct
81 plain
81 mail
81 retire
81 opposite
81 prefer
81 safe
81 evil
81 double
81 wood
80 empty
80 baby
80 advise
80 content
80 sport
80 lift
80 literary
80 curious
80 tie
80 flat
80 message
80 neck
79 hate
79 dirt
79 delight
79 trust
79 nobody
79 valley
79 tool
78 presence
78 cook
78 railroad
78 minister
78 coffee
78 brush
78 beside
78 collect
77 guide
77 luck
77 profit
77 lord
77 everybody
77 prison
77 cloud
77 slave
77 chairman
76 soil
76 distinguish
76 introduce
76 urge
76 blind
75 arise
75 upper
75 curve
75 membership
75 key
75 entertain
75 soul
75 neighborhood
74 friendly
74 pair
74 stone
74 lean
74 protect
74 advertise
74 mystery
73 welcome
73 knee
73 jump
73 snake
73 stream
73 avenue
73 brown
73 disease
73 hat
73 excellent
72 formal
72 snow
72 sheet
72 somehow
72 unity
72 sky
72 rough
72 smooth
72 weather
72 steady
72 threaten
72 depth
71 oppose
71 deliver
71 ancient
71 pray
71 adopt
71 birth
71 appearance
71 universe
71 busy
71 hurry
71 coast
71 forth
70 smell
70 furnish
70 female
70 hide
70 wire
70 proposal
70 ought
70 victory
69 quarter
69 engine
69 customer
69 waste
69 fool
69 intend
69 intention
69 desk
69 politics
69 passage
69 lawyer
68 root
68 climb
68 metal
68 gradual
68 hunt
68 protection
68 satisfy
68 roof
68 branch
68 pleasure
68 witness
68 loose
67 nose
67 mine
67 band
67 aside
67 risk
67 tomorrow
67 remind
67 ear
67 fish
67 shore
66 operator
66 civilize
66 being
66 silent
66 screen
66 bind
66 earn
66 pack
66 colony
66 besides
66 slip
66 cousin
66 scale
66 relief
66 explore
66 stem
65 brain
65 musician
65 defend
65 bend
65 somebody
65 shadow
64 mix
64 smoke
64 description
64 fruit
64 guilt
64 yield
64 sensitive
64 salt
64 pale
64 sweep
64 completion
64 throat
64 agriculture
64 admire
63 gentle
63 dozen
63 particle
63 pleasant
63 bay
63 cup
63 competition
63 moon
63 terrible
63 strip
63 mechanic
63 shock
63 conversation
63 angle
62 tall
62 plenty
62 star
62 yellow
62 sick
62 thorough
62 absolute
62 succeed
61 surround
61 proud
61 dear
61 card
61 lake
61 breath
61 afraid
61 silence
61 onto
60 shoe
60 somewhere
60 chain
60 slide
60 copy
60 machinery
60 wake
60 severe
60 pocket
60 bone
59 honest
59 freeze
59 dictionary
59 calm
59 swim
59 ice
59 male
59 skin
59 crack
59 rush
59 wet
58 meat
58 commerce
58 joint
58 gift
58 host
58 suspect
58 path
58 uncle
58 afford
58 instant
58 satisfactory
58 height
58 track
58 confidence
58 grass
57 suggestion
57 favorite
57 breakfast
57 apart
57 chest
57 entrance
57 march
57 sink
57 northern
57 iron
57 alive
57 ill
57 bag
57 disturb
57 native
57 bedroom
57 violent
57 beneath
57 pause
57 tough
56 substance
56 threat
56 charm
56 absence
56 factory
56 spite
56 meal
56 universal
56 accident
56 highway
56 sentence
56 liberty
55 wise
55 noise
55 discovery
55 tube
55 flash
55 twist
55 fence
55 childhood
55 joy
55 sister
54 sad
54 efficiency
54 disappear
54 defeat
54 extensive
54 rent
54 comparison
54 possess
54 grace
54 flesh
54 liquid
54 scientist
54 ease
53 heaven
53 milk
53 sympathy
53 rank
53 restaurant
53 frequency
53 angry
53 shade
53 accuse
53 necessity
53 knock
53 loud
53 permanent
53 row
53 lovely
53 confuse
52 gold
52 frighten
52 solve
52 grave
52 salary
52 photograph
52 advice
52 abroad
51 wound
51 virtue
51 dare
51 queen
51 extra
51 attract
50 numerous
50 pink
50 gate
50 expensive
50 shut
50 chicken
50 forgive
50 holy
50 wooden
49 prompt
49 crime
49 sorry
49 republic
49 anger
49 visitor
49 pile
49 violence
49 steel
49 wing
49 stair
49 partner
49 delay
49 gentleman
48 pour
48 confusion
48 damage
48 kick
48 safety
48 burst
48 network
48 resistance
48 screw
48 pride
48 till
47 hire
47 verb
47 preach
47 clerk
47 everywhere
47 anyway
47 fan
47 connect
47 egg
47 efficient
47 grain
46 calculate
46 drag
46 opposition
46 worship
46 arrest
46 discipline
46 string
46 harbor
46 camera
46 mechanism
46 cow
46 grand
46 funny
46 insurance
46 reduction
46 strict
46 lesson
46 tight
45 sand
45 plate
45 qualify
45 elsewhere
45 mad
45 interference
45 pupil
45 fold
45 royal
45 valuable
45 whisper
45 anybody
45 hurt
45 excess
44 quantity
44 fun
44 mud
44 extension
44 recognition
44 kiss
44 crop
44 sail
44 attractive
44 habit
44 relieve
44 wisdom
44 persuade
43 certainty
43 cloth
43 eager
43 deserve
43 sympathetic
43 cure
43 trap
43 puzzle
43 powder
43 raw
43 mankind
43 glad
43 blame
43 whenever
43 anxiety
42 bus
42 tremble
42 sacred
42 fortunate
42 glory
42 golden
42 neat
42 weekend
42 treasury
42 overcome
42 cat
42 sacrifice
42 complain
42 elect
41 roar
41 sake
41 temple
41 self
41 compete
41 nurse
41 stuff
41 stomach
41 peculiar
41 repair
41 storm
41 ton
41 desert
41 allowance
41 servant
41 hunger
41 conscience
41 bread
41 crash
40 tip
40 strengthen
40 proof
40 generous
40 sir
40 tonight
40 whip
40 tongue
40 mill
40 merchant
40 coal
40 ruin
40 introduction
40 courage
40 actor
40 belt
39 stir
39 package
39 punish
39 reflection
39 breathe
39 anywhere
39 amuse
39 dull
39 fate
39 net
39 fellowship
39 fault
39 furniture
39 beam
39 pencil
39 border
39 disappoint
38 flame
38 joke
38 bless
38 corn
38 shell
38 tempt
38 supper
38 destruction
38 dive
38 anxious
38 shine
38 cheap
38 dish
38 distant
38 greet
37 flood
37 excuse
37 insect
37 ocean
37 ceremony
37 decrease
37 prize
37 harm
37 insure
37 verse
37 pot
37 sincere
36 cotton
36 leaf
36 rub
36 medicine
36 stroke
36 bite
36 lung
36 lonely
36 admission
36 stupid
36 scratch
36 composition
36 broadcast
36 drum
36 resist
36 neglect
35 absent
35 passenger
35 adventure
35 beg
35 pipe
35 beard
35 bold
35 meanwhile
35 devil
35 cheer
35 nut
35 split
35 melt
35 swear
35 sugar
35 bury
35 wipe
35 faint
35 creature
35 tail
35 wealth
34 earnest
34 translate
34 suspicion
34 noble
34 inquiry
34 journey
34 hesitate
34 extraordinary
34 borrow
34 owe
34 funeral
34 ambition
34 mixture
34 slope
34 criminal
34 seldom
34 map
34 spin
34 praise
34 spare
33 plow
33 telegraph
33 barrel
33 straighten
33 scarce
33 lunch
33 slavery
33 creep
33 sweat
33 gay
33 stiff
33 brave
33 seize
33 convenient
33 horizon
33 moderate
33 complicate
33 dig
33 curse
33 weigh
33 priest
33 excessive
33 quarrel
32 widow
32 modest
32 dine
32 politician
32 custom
32 educate
32 salesman
32 nail
32 tap
32 eastern
32 possession
32 satisfaction
32 behave
32 mercy
31 scatter
31 objection
31 silver
31 tent
31 saddle
31 wrap
31 nest
31 grind
31 spell
31 plaster
31 arch
31 swell
31 friendship
31 bath
30 bundle
30 grateful
30 crown
30 boundary
30 nowhere
30 asleep
30 clock
30 boil
30 altogether
30 lend
30 holiday
30 precious
30 wander
30 ugly
30 reputation
30 ticket
30 pretend
30 dismiss
30 delicate
29 despair
29 awake
29 tea
29 FALSE
29 fortune
29 cap
29 thread
29 haste
29 bare
29 shirt
29 bargain
28 leather
28 rail
28 butter
28 dot
28 inquire
28 warmth
28 decisive
28 vessel
28 pity
28 steam
28 pin
28 bound
28 companion
28 toe
28 reward
28 forbid
28 wherever
28 tower
27 bathe
27 lodge
27 swallow
27 multiply
27 bow
27 kingdom
27 garage
27 permission
27 pump
27 prevention
27 urgent
27 aunt
27 zero
27 idle
27 fever
27 christmas
27 regret
26 jaw
26 soap
26 pronounce
26 empire
26 bowl
26 outline
26 organ
26 imitation
26 caution
26 mineral
26 disagree
26 blade
26 trick
26 treasure
26 immense
25 convenience
25 disapprove
25 destructive
25 fork
25 noon
25 ownership
25 tune
25 polish
25 poison
25 shame
25 loyalty
25 cottage
25 astonish
25 shave
25 feather
25 sauce
25 lid
25 debt
25 fade
25 confess
25 classification
24 descend
24 cape
24 mild
24 clever
24 envelope
24 invention
24 sheep
24 splendid
24 stamp
24 float
24 brick
24 rice
24 businessman
24 backward
24 qualification
24 artificial
24 attraction
24 lamp
24 curl
23 shower
23 elder
23 bunch
23 bell
23 steer
23 flavor
23 spit
23 rob
23 cream
23 interrupt
23 pen
23 weave
23 orange
23 rescue
23 crush
23 humble
23 fancy
23 decay
23 polite
23 tribe
22 bleed
22 coin
22 fond
22 autumn
22 classify
22 omit
22 loyal
22 needle
22 lessen
22 complaint
22 pad
22 steep
22 skirt
22 curtain
22 calculation
22 laughter
22 solemn
22 grease
22 interfere
22 explode
22 fasten
21 flag
21 resign
21 postpone
21 patience
21 boast
21 rope
21 envy
21 airplane
21 rid
21 shield
21 veil
21 kneel
21 tray
21 explosive
21 brass
21 taxi
21 wax
21 duck
21 button
21 invent
20 remedy
20 bush
20 thunder
20 weaken
20 poverty
20 scrape
20 arrow
20 tender
20 cruel
20 soften
20 mouse
20 hay
20 anyhow
20 alike
20 circular
20 juice
20 shelf
20 bake
20 hatred
20 cautious
19 basket
19 wreck
19 width
19 confident
19 log
19 heap
19 suck
19 ladder
19 gap
19 obey
19 hut
19 axe
19 translation
19 collar
19 delivery
19 reproduce
19 confession
19 pan
19 prejudice
19 voyage
19 tobacco
18 simplicity
18 paste
18 cake
18 elephant
18 ribbon
18 harvest
18 ashamed
18 cave
18 customary
18 thief
18 damp
18 sew
18 rust
18 separation
18 waiter
18 pet
18 straw
18 upset
18 towel
18 refresh
17 essence
17 fur
17 ambitious
17 defendant
17 daylight
17 dip
17 suspicious
17 imaginary
17 ash
17 carriage
17 educator
17 saw
17 stove
17 rubber
17 rug
17 misery
17 awkward
17 rival
16 roast
16 deed
16 preference
16 explosion
16 theatrical
16 cultivate
16 collector
16 miserable
16 wrist
16 rabbit
16 accustom
16 tide
16 insult
16 thumb
16 lump
16 annoy
16 toy
16 heal
16 shallow
16 repetition
16 soup
15 whistle
15 scenery
15 apple
15 offense
15 cork
15 ripe
15 temper
15 sore
15 pinch
15 diamond
15 razor
15 imaginative
15 hook
15 copper
15 landlord
14 influential
14 rot
14 hollow
14 enclose
14 harden
14 wicked
14 stiffen
14 silk
14 upright
14 selfish
14 stripe
14 pig
14 inward
14 excellence
14 rake
14 purple
14 hasten
14 shorten
14 applause
14 ache
14 apology
14 knot
14 nephew
14 cushion
14 drown
14 nursery
14 pint
14 fierce
13 imitate
13 aloud
13 gaiety
13 robbery
13 tighten
13 perfection
13 scorn
13 whoever
13 trunk
13 wool
13 sailor
13 competitor
13 moonlight
13 deer
13 bean
13 everyday
13 drawer
13 disregard
12 nowadays
12 patriotic
12 tin
12 penny
12 cage
12 pardon
12 lately
12 offend
12 coarse
12 spoil
12 horizontal
12 sting
12 ditch
12 librarian
12 meantime
12 cough
12 deaf
12 sword
12 messenger
12 vain
12 castle
12 elastic
12 comb
12 rod
11 widen
11 sorrow
11 inventor
11 cliff
11 umbrella
11 interruption
11 merry
11 gallon
11 conquest
11 headache
11 tailor
11 bucket
11 scent
11 signature
11 cart
11 darken
11 sometime
11 applaud
11 underneath
11 hello
11 pretense
11 descent
11 conquer
11 framework
11 confidential
11 adoption
11 disgust
11 waist
11 momentary
11 receipt
10 pearl
10 ray
10 lazy
10 limb
10 grammatical
10 beast
10 monkey
10 jewel
10 persuasion
10 obedience
10 sock
10 vowel
10 hammer
10 inn
10 chimney
10 dissatisfaction
10 annoyance
10 ornament
10 honesty
10 outward
10 sharpen
10 handkerchief
9 greed
9 heavenly
9 thirst
9 niece
9 spill
9 loaf
9 wheat
9 worm
9 secrecy
9 rude
9 heighten
9 flatten
9 loosen
9 cheese
9 rivalry
9 royalty
9 discontent
9 complication
9 fright
9 indoor
9 flour
9 actress
8 congratulation
8 ounce
8 fry
8 everlasting
8 goat
8 ink
8 disappearance
8 reproduction
8 thicken
8 avoidance
8 spoon
8 strap
8 deceive
7 lengthen
7 revenge
7 correction
7 descendant
7 hesitation
7 spade
7 basin
7 weed
7 omission
7 old-fashioned
7 bicycle
7 breadth
7 photography
7 coward
7 mat
7 rejoice
7 cheat
7 congratulate
7 discomfort
7 enclosure
7 attentive
7 paw
6 overflow
6 dissatisfy
6 multiplication
6 whichever
6 tidy
6 bribe
6 mend
6 stocking
6 feast
6 nuisance
6 thorn
6 tame
5 inclusive
5 homemade
5 handwriting
5 chalk
5 sour
5 slippery
5 procession
5 ripen
5 jealous
5 jealousy
5 liar
5 homecoming
5 barber
5 whiten
5 berry
5 lighten
5 pigeon
5 hinder
4 bravery
4 baggage
4 noun
4 amongst
4 grammar
4 cultivation
4 companionship
4 rubbish
4 modesty
4 woolen
4 deepen
4 pastry
4 cupboard
4 quart
4 canal
4 notebook
4 deceit
3 parcel
3 brighten
3 moderation
3 punctual
3 hurrah
3 lipstick
3 uppermost
3 fatten
3 conqueror
2 hindrance
2 cowardice
2 obedient
2 saucer
2 madden
2 scold
2 weekday
2 rotten
2 disrespect
1 widower
1 deafen
1 donkey
1 businesslike
1 motherhood
1 sadden
1 handshake
1 calculator
1 headdress
1 scissors
1 translator
1 possessor
1 shilling
1 redden
1 motherly
0 whose
0 cultivator
0 whom
0 homework
0 electrician
0 oar
0 bribery
0 sweeten
0 sow
0 pronunciation
0 beak
0 plural

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Preface to the Poems Collected from the Orchid Pavilion