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<a class="post-title-link" href="/2018/05/06/初步搭建开源PT程序NexusPHP/" itemprop="url">初步搭建开源PT程序NexusPHP</a></h1>
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2018-05-06
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<p>本学期开学，宿舍里最大的变化就是学校正式开通了LCU-Wifi宿舍无线，属于教育网双栈，30M/s ipv4，100M/s ipv6。<br>比较坑的是，我校ipv6使用也需要登陆，还好没有v4的流量限制。使用ipv6去TUNA镜像网站下载速度能跑满网速。前期听老师们说v6可以高速PT下载，自己就在网上找了找资料。</p>
<blockquote>
<p>PT（Private Tracker）下载其实也是Bt下载的一种，但有两个明显的改进：<br>一是私密的小范围下载，二是进行流量统计，根据上载量决定你的权限。 BT下载时，软件会分析.torrent种子文件得到Tracker地址，然后连接Tracker服务器，服务器返回其他下载者的IP，下载者再与这些IP联系进行下载，从而减轻了服务器的负担，BT下载的Tracker是公开的，而Private Tracker 下载(PT下载)的Tracker则是私有的，每个人的Tracker是不同的，即passkey不同，passkey对PT下载者很重要，所以不要轻易泄露出去。</p>
</blockquote>
<p>购买了校园网无线以后，为了更好的利用ipv6，我使用我校的.edu.cn邮箱，注册了一个西工大蒲公英pt，第一次体验下载了个视频，果然速度美滋滋。</p>
<p>目前在实验室我有一台自己使用的电脑，与宿舍的无线基本上共属于同一台局域网，并且可以指定教育网ip，v6的ip也是重启后才会更换，了解到浙大在2010年开源了一个PT程序————NexusPHP，我就开始在实验室的电脑上初步搭建。</p>
<p>以下记录了我这三天来的搭建实例，可复现。</p>
<p>开始之前先科普一下上述中的基本知识。</p>
<blockquote>
<p>Ubuntu：世界有名的Linux桌面版，采用的最新版16.04.4LTS。</p>
<p>Nginx： 采用Ubuntu apt 安装方式安装的1.13.3版本。</p>
<p>MySQL：也是用的Ubuntu apt安装方式，版本为5.7.21。</p>
<p>Php：安装方式同上，版本为5.6。<strong><em>注意，必须使用5.6版本，新版7.X与本项目不兼容。</em></strong></p>
<p>nexusPHP:这是NexusPHP由来自浙江大学的Nexus团队发起并开发完成。它的目标是代替TBSource项目，提供一个完整的、有序的、重视用户信誉和知识的资源分享社区的解决方案。 这是一个比较老的BT开源项目，2010年开源的。</p>
</blockquote>
<hr>
<p>介绍完毕，开始干活！</p>
<h2 id="安装MySQL"><a href="#安装MySQL" class="headerlink" title="安装MySQL"></a>安装MySQL</h2><p>1、启动终端，输入以下代码安装：</p>
<pre><code>sudo apt update
sudo apt-get install mysql-server
sudo apt install libmysqlclient-dev
</code></pre><ul>
<li>安装过程会提示设置mysql root用户的密码，设置完成后等待自动安装即可。默认安装完成就启动了mysql。</li>
<li>安装成功后可以通过下面的命令测试是否安装成功：<br><code>sudo netstat -tap | grep mysql</code></li>
</ul>
<p>2、更改mysql字符集为utf8:</p>
<pre><code>#分别用编辑器打开两个文件#
sudo gedit /etc/mysql/mysql.conf.d/mysqld.cnf
sudo gedit /etc/mysql/conf.d/mysql.cnf
</code></pre><ul>
<li>在[mysqld]下添加一行 <code>character_set_server=utf8</code></li>
<li>在[mysql]下添加一行 <code>default_character_set=utf8</code></li>
<li>使用 <code>service mysql restart</code>重启mysql服务。</li>
</ul>
<h2 id="安装Nginx"><a href="#安装Nginx" class="headerlink" title="安装Nginx"></a>安装Nginx</h2><p>启动终端，输入以下代码安装：</p>
<pre><code>sudo apt install nginx
</code></pre><ul>
<li>浏览器输入 <code>localhost</code>，出现 nginx 欢迎界面则表示成功</li>
</ul>
<h2 id="安装PHP5-6"><a href="#安装PHP5-6" class="headerlink" title="安装PHP5.6"></a>安装PHP5.6</h2><p>1、添加PPA。</p>
<pre><code>sudo apt install python-software-properties software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt update
</code></pre><p>2、安装PHP5.6以及扩展。</p>
<pre><code>sudo apt install php5.6-fpm php5.6-mysql php5.6-common php5.6-curl php5.6-cli php5.6-mcrypt php5.6-mbstring php5.6-xml
</code></pre><p>3、配置PHP5.6：</p>
<pre><code>sudo gedit /etc/php/5.6/fpm/php.ini
</code></pre><ul>
<li><p>找到cgi.fix_pathinfo选项，去掉注释;，然后将值设置为0:</p>
<p> <code>cgi.fix_pathinfo = 0</code></p>
</li>
</ul>
<p>4、再次配置Nginx：</p>
<pre><code>sudo gedit /etc/nginx/sites-available/default
</code></pre><p>去掉 <code>location ~ \.php</code> 整个闭包的注释，并将其修改为：</p>
<pre><code>location ~ \.php$ {
# include snippets/fastcgi-php.conf;
#
# # With php7.0-cgi alone:
# fastcgi_pass 127.0.0.1:9000;
# # With php7.0-fpm:
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_pass unix:/run/php/php5.6-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;
}
</code></pre><p>5、重启Nginx 和 PHP5.6并测试：</p>
<pre><code>sudo service php5.6-fpm restart
sudo service nginx restart
</code></pre><ul>
<li>使用 <code>echo "<?php phpinfo(); ?>" >> /var/www/html/phpinfo.php</code> 生成测试文件。</li>
<li>从浏览器打开 <code>localhost/phpinfo.php</code>，出现 php的一系列信息则表示配置成功。</li>
</ul>
<h2 id="开始NexusPHP安装实战"><a href="#开始NexusPHP安装实战" class="headerlink" title="开始NexusPHP安装实战"></a>开始NexusPHP安装实战</h2><h2 id="安装MemCache-MemCached"><a href="#安装MemCache-MemCached" class="headerlink" title="安装MemCache/MemCached"></a>安装MemCache/MemCached</h2><p>1、启动终端，输入以下代码安装：</p>
<pre><code>sudo apt install memcached
sudo apt install php-memcache
sudo apt install php-memcached
</code></pre><p>2、配置php.ini。</p>
<ul>
<li>寻找 扩展目录 :<br> <code>find /usr -name "memcache*</code></li>
</ul>
<p>示例输出:</p>
<pre><code>/usr/lib/php/20131226/memcache.so
/usr/lib/php/20131226/memcached.so
</code></pre><ul>
<li>根据以上输出，修改php.ini文件。<br>①把php.ini中的 <code>extension_dir = "./"</code> 修改为 <code>extension_dir = "/usr/lib/php/20131226/"</code>并去掉注释。②添加两行来载入memcache/memcached扩展：<code>extension=memcache.so</code> <code>extension=memcached.so</code> </li>
</ul>
<p>3、Memcache环境测试： </p>
<ul>
<li>在/var/www/html/下创建以下面为内容的memcached.php文件。创建完毕后使用浏览器访问 <code>localhost/memcache.php</code> ，如果有输出 <code>This is a test!</code> ，就表示环境搭建成功。</li>
</ul>
<h2 id="安装Pear和HTTP-Request2"><a href="#安装Pear和HTTP-Request2" class="headerlink" title="安装Pear和HTTP_Request2"></a>安装Pear和HTTP_Request2</h2><p>启动终端，输入以下代码安装:</p>
<pre><code>sudo apt install php-pear
sudo pear config-set preferred_state alpha
pear install HTTP_Request2
</code></pre><h2 id="安装-phpmyadmin-并配置"><a href="#安装-phpmyadmin-并配置" class="headerlink" title="安装 phpmyadmin 并配置"></a>安装 phpmyadmin 并配置</h2><p>启动终端，输入以下代码安装并配置:</p>
<pre><code>sudo apt install phpmyadmin
cd /var/www/html && ln -s /usr/share/phpmyadmin
sudo service nginx restart
</code></pre><p>然后打开浏览器访问 <code>localhost/phpmyadmin/index.php</code> 出现 <code>欢迎使用phpmyadmin</code> ye’mian则表示成功。</p>
<h2 id="开始正式安装nexusPHP"><a href="#开始正式安装nexusPHP" class="headerlink" title="开始正式安装nexusPHP"></a>开始正式安装nexusPHP</h2><p>1、首先从sourceforge官网下载NexusPHP源码镜像并解压至网站目录。</p>
<pre><code>wget https://nchc.dl.sourceforge.net/project/nexusphp/nexusphp.v1.5.beta5.20120707.zip
unzip -o nexusphp* -d /var/www/html/
</code></pre><p>2、恢复原网站msyqldump文件。</p>
<pre><code>mysql -u root -p password
# 输入密码 #
mysql > create database nexusphp;
mysql > use nexusphp;
mysql > source /var/www/html/_db/dbstructure.sql;
</code></pre><ul>
<li>打开 localhost/phpmyadmin/index.php 确认数据表是否添加成功。</li>
</ul>
<p>3、修改配置文件allconfig.php。</p>
<pre><code>gedit /var/www/html/config/allconfig.php
</code></pre><p>修改 <code>$BASIC=array</code> 闭包为以下内容：</p>
<pre><code>$BASIC=array(
'SITENAME' => 'NexusPHP',
'BASEURL' => 'localhost',
'announce_url' => 'localhost/announce.php',
'mysql_host' => 'localhost',
'mysql_user' => 'root',
'mysql_pass' => '数据库密码',
'mysql_db' => 'nexusphp',
</code></pre><p>);</p>
<ul>
<li>请用正确密码匹配以上信息。</li>
</ul>
<p>4、设置管理员。</p>
<ul>
<li>首先自己访问网站然后注册一个用户名，接着进入数据库管理（phpMyAdmin），在users表里面找到你注册的用户，编辑它的class属性为16，完成。</li>
</ul>
<p><strong>到这里PT基本上就架设完毕了，现在只需要利用管理员帐号对站点进行设置和调整就可以了。</strong></p>
<p>浏览器输入localhost/nexusphp/login.php 出现登陆页面则表示成功。</p>
<hr>
<p>部分信息来自：</p>
<ul>
<li><a href="http://blog.csdn.net/Mikeoperfect/article/details/78868185" target="_blank" rel="noopener">http://blog.csdn.net/Mikeoperfect/article/details/78868185</a></li>
<li><a href="https://www.zhihu.com/question/27344154/answer/105577094" target="_blank" rel="noopener">https://www.zhihu.com/question/27344154/answer/105577094</a></li>
</ul>
<p><strong>著作权归作者所有。</strong></p>
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<a class="post-title-link" href="/2018/05/06/斐波那契数列问题的非递归实现/" itemprop="url">斐波那契数列问题的非递归实现</a></h1>
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<time title="创建于" itemprop="dateCreated datePublished" datetime="2018-05-06T17:27:33+08:00">
2018-05-06
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<h2 id="问题引入"><a href="#问题引入" class="headerlink" title="问题引入"></a>问题引入</h2><p>有一对兔子，从出生后第3个月起每个月都生一对兔子，小兔子长到第三个月后每个月又生一对兔子，假如兔子都不死，问每个月的兔子对数为多少？ </p>
<h2 id="程序分析"><a href="#程序分析" class="headerlink" title="程序分析"></a>程序分析</h2><p>兔子的规律为数列1，1，2，3，5，8，13，21 … ，属于斐波那契数列问题。该数列有一个规律: F(0) = 1 , F(1) = 1, F(n) = F(n-1) + F(n-2)(n>=2) …</p>
<p>由此可以用递归的方法实现，这样写出的代码比较简洁.</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Prog1</span> </span>{</span><br><span class="line"> <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">main</span><span class="params">(String[] args)</span> </span>{</span><br><span class="line"> <span class="keyword">int</span> n = <span class="number">50</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">int</span> i = <span class="number">1</span>; i <= n; i++) {</span><br><span class="line"> System.out.println(<span class="string">"After "</span> + i + <span class="string">" mouths, the number of rabbit is "</span> + fun2(i));</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> </span><br><span class="line"> <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">long</span> <span class="title">fun2</span><span class="params">(<span class="keyword">int</span> n)</span> </span>{</span><br><span class="line"> <span class="keyword">if</span> (n == <span class="number">1</span> || n == <span class="number">2</span>)</span><br><span class="line"> <span class="keyword">return</span> <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">else</span> {</span><br><span class="line"> <span class="keyword">return</span> fun(n-<span class="number">1</span>) + fun(n-<span class="number">2</span>);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<p>这样的递归算法虽然只有简单的几行，但是效率却很低。为什么呢？我们可以分析其递归调用的时间复杂度： </p>
<p><strong>时间复杂度</strong> —– O(2^N) </p>
<p>由于使用递归时，其执行步骤是：要得到后一个数之前必须先计算出之前的两个数，即在每个递归调用时都会触发另外两个递归调用，例如：要得到F(10)之前得先得到F(9)、F(8)，那么得到F(9)之前得先得到F(8)、F(7)……如此递归下去 。</p>
<p>这样的计算是以 2 的次方在增长的。</p>
<p>除此之外，我们也可以看到，F(8)和F(7)的值都被多次计算，如果递归的深度越深，那么F(8)和F(7)的值会被计算更多次，但是这样计算的结果都是一样的，除了其中之一外，其余的都是浪费，可想而知，这样的开销是非常恐怖的 。</p>
<p>所以，如果在时间复杂度和空间复杂度都有要求的话，我们可以用以下的非递归算法来实现。</p>
<h2 id="非递归算法"><a href="#非递归算法" class="headerlink" title="非递归算法"></a>非递归算法</h2><p><strong>时间复杂度为<em>O(N)</em>，空间复杂度为<em>O(1)</em> </strong></p>
<p><strong>思路</strong>：借助两个变量 first 和 second ，每次将 first 和 second 相加后赋给 third ，再将 second 赋给 first ，third 赋给 second，如此循环。 </p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">Prog1</span> </span>{</span><br><span class="line"> <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">main</span><span class="params">(String[] args)</span> </span>{</span><br><span class="line"> <span class="keyword">int</span> n = <span class="number">50</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">int</span> i = <span class="number">1</span>; i <= n; i++) {</span><br><span class="line"> System.out.println(<span class="string">"After "</span> + i + <span class="string">" mouths, the number of rabbit is "</span> + fun2(i));</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> </span><br><span class="line"> <span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">long</span> <span class="title">fun</span><span class="params">(<span class="keyword">int</span> n)</span> </span>{</span><br><span class="line"> <span class="keyword">long</span> first = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">long</span> second = <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">long</span> third = <span class="number">1</span>;</span><br><span class="line"> <span class="keyword">for</span> (<span class="keyword">int</span> i = <span class="number">2</span>; i <= n; i++) {</span><br><span class="line"> third = first + second;</span><br><span class="line"> first = second;</span><br><span class="line"> second = third;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> third;</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
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