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map, filter, reduce 是函数式编程的函数, 不再需要循环分支使得代码更加简洁。map/reduce 和google的map/reduce功能是类似的， filter有些类似shuffle, 当然shuffle更多的工作是将相同的key放到同一个reduce计算中 map 1 map(function_to_apply, list_of_inputs) 例如： 1 2 3 4 5 items = [1,2,3,4,5] squared = [] for i in items: squared.append(i**2) print(squared) <=> 等价于 1 2 3 items = [1,2,3,4,5] squared = list(map(lambda x: x**2, items)) print(squared) filter 1 filter(function_to_apply, list_of_inputs) 接着上面的代码继续 1 2 3 4 5 less_than_ten=[] for i in squared: if i < 10: less_than_ten.append(i) print(less_than_ten) <=> 等价于 1 2 3 less_than_ten=[] less_than_ten = list(filter(lambda x: x<10, squared)) print(less_than_ten) reduce 1 reduce(function_to_apply, list_of_inputs) 和上面两个函数不同， reduce将进行迭代合并操作 1 2 3 4 product = 0 for i in less_than_ten: product = product + i print(product) <=> 等价于 ...

本周在学习Trie数据结构的时候，看到了他的发明者 Edward Fredkin，他也在研究reversible computing 弗雷德金（Fredkin）对计算，硬件和软件一直很感兴趣。 在1960年代初期，他在BBN编写了第一台PDP-1汇编程序。 他是trie数据结构，Fredkin gate和Billiard-Ball计算机模型的可逆计算的发明者。 他的主要贡献包括他在可逆计算和元胞自动机方面的工作。 他还研究领域还包括计算机视觉，人工智能研究和计算机象棋。 ...

File Searching Using Variable Length Keys 最早提及Trie树的一篇文章 MANY computer applications require the storage of large amounts of information within the computer’s memory where it will be readily available for reference and updating. Quite commonly, more storage space is required than is available in the computer’s high-speed working memory. It is, therefore, a common practice to equip computers with magnetic tapes, disks, or drums, or a combination of these to provide additional storage. This additional storage is always slower in operation than the computer’s working memory and therefore care must be taken when using it to avoid excessive operating time. ...

题目： In English, we have a concept called root, which can be followed by some other word to form another longer word - let’s call this word successor. For example, when the root "an" is followed by the successor word "other", we can form a new word "another". Given a dictionary consisting of many roots and a sentence consisting of words separated by spaces, replace all the successors in the sentence with the root forming it. If a successor can be replaced by more than one root, replace it with the root that has the shortest length. ...

1 . 环境： cenos7(X86_64) + openssh 2 . 安装 配置镜像加速器, 尝试从Docker Hub下载, 速度太慢 /etc/docker/daemon.json 1 2 3 4 5 6 7 { "max-concurrent-downloads":1, "registry-mirrors": [ "https://hub-mirror.c.163.com", "https://mirror.baidubce.com" ] } 抓取zookeeper镜像 1 docker pull zookeeper 抓取dubbo-admin镜像 1 docker pull apache/dubbo-admin 启动zookeeper容器 1 docker run --name zookeeper -p 2181:2181 -d zookeeper 启动duboo-admin容器 1 2 3 4 5 6 docker run -d \ -p 8081:8080 \ -e dubbo.registry.address=zookeeper://192.168.37.201:2181 \ -e dubbo.admin.root.password=root \ -e dubbo.admin.guest.password=guest \ apache/dubbo-admin 验证 浏览器输入 1 http://192.168.37.201:8081/ 参考及引用 http://blog.csdn.net/zxl8899/article/details/107413063 Photo by Steve Johnson from Pexels

1 . 环境： cenos7(X86_64) + openssh 2 . 安装 配置镜像加速器, 尝试从Docker Hub下载, 速度太慢 /etc/docker/daemon.json 1 2 3 4 5 6 7 { "max-concurrent-downloads":1, "registry-mirrors": [ "https://hub-mirror.c.163.com", "https://mirror.baidubce.com" ] } 抓取tomcat镜像 1 docker pull tomcat 启动容器 1 docker run -d --name tongda-user -p 8082:8080 -v /root/log/user-log:/usr/local/tomcat/user-log tomcat 验证容器 http://xxx.xxx.xxx.xxx:8082 1 2 3 4 HTTP状态 404 - 未找到 类型 状态报告 描述 源服务器未能找到目标资源的表示或者是不愿公开一个已经存在的资源表示。 Apache Tomcat/9.0.41 调整 1 2 3 4 docker exec -it mytomcat /bin/bash mv webapps webapps2 mv webapps.dist/ webapps exit 验证成功 ...

环境： cenos7(X86_64) + openssh 安装工具yum 安装 1 检查更新 1 sudo yum check-update 2 安装依赖包 1 sudo yum install -y yum-utils device-mapper-persistent-data lvm2 3 增加docker repo地址 1 sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo 4 安装docker 1 sudo yum install docker 5 启动docker服务查看状态 1 sudo systemctl start docker 开机启动 1 sudo systemctl enable docker 查看状态 1 sudo systemctl status docker0 参考及引用 https://phoenixnap.com/kb/how-to-install-docker-centos-7 Photo by Steve Johnson from Pexels

spring boot + maven配置, 创建一个包含多个模块项目的步骤 项目创建 使用spring的initializr 选择一下就可以生成代码 项目: tongda (jar) 模块: user (war) order (war) common (jar) 配置: Project : Maven Project Language : Java Spring Boot : 2.4.1 Dependencies: Java : 11 Packaging :jar/war 调整 parent POM 修改tongda的pom.xml, 打包类型设置为pom 新增packaging 标签并设置为pom 1 <packaging>pom</packaging> 通知增加模块配置 1 2 3 4 5 <modules> <module>user</module> <module>order</module> <module>common</module> </modules> 各个模块中调整parent标签 order, user模块 pom.xml文件 1 2 3 4 5 6 <parent> <groupId>com.tongda</groupId> <artifactId>tongda</artifactId> <version>0.0.1-SNAPSHOT</version> <relativePath>../pom.xml</relativePath> </parent> 验证 1 2 3 4 5 6 7 8 9 10 11 12 > mvn clean package ... [INFO] Reactor Summary: [INFO] [INFO] tongda 0.0.1-SNAPSHOT .............................. SUCCESS [ 1.250 s] [INFO] user ............................................... SUCCESS [ 9.161 s] [INFO] order .............................................. SUCCESS [ 6.106 s] [INFO] common 0.0.1-SNAPSHOT .............................. SUCCESS [ 4.226 s] [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ ... 参考引用 https://www.baeldung.com/maven-multi-module https://github.com/bz51/SpringBoot-Dubbo-Docker-Jenkins Photo by Zaksheuskaya from Pexels

学习java, 尝试用了spring boot创建了一个项目， 使用是maven配置, spring boot 提供很多的模板， 创建项目非常方便， 这让我想起了visual studio 点击几下鼠标自动生成模板代码。 项目创建 使用spring的initializr 选择一下就可以生成代码 我的配置: Project : Maven Project Language : Java Spring Boot : 2.4.1 Dependencies: Spring Web 创建一个web项目 Spring Boot Actuator 提供健康检查功能 Lombok: 通过注释说明生成代码需要安装相关插件 Java : 11 Packaging :jar 相关代码 : 自动生成代码如下: 1 2 3 4 5 6 7 8 9 10 11 12 13 package com.garlicspace.demo; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication @RestController public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } } 通过"/hello"文根实现页面输出"hello World!" 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 package com.garlicspace.demo; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @SpringBootApplication @RestController public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } @RequestMapping("/hello") public String hello(){ return "hello World!"; } } cmd运行: ...

题目： Implement a MapSum class with insert, and sum methods. For the method insert, you’ll be given a pair of (string, integer). The string represents the key and the integer represents the value. If the key already existed, then the original key-value pair will be overridden to the new one. For the method sum, you’ll be given a string representing the prefix, and you need to return the sum of all the pairs’ value whose key starts with the prefix. ...