B. Margarite and the best present 题目链接:https://codeforces.com/contest/1080/problem/B 题意: 给出一个数列:an=(-1)n,之后有询问,问 [l,r] 之间的ai和为多少. 题解:这个分情况讨论一下就可以了,区间长度的奇偶数丶左端点的奇偶数. 代码如下: #include <cstdio> #include <cstring> #include <algorithm> #include…

Little girl Margarita is a big fan of competitive programming. She especially loves problems about arrays and queries on them. Recently, she was presented with an array aa of the size of 109109 elements that is filled as follows: a1=−1a2=2a3=−3a4=4a5…

Content 有 \(t\) 次询问,每次询问给定两个整数 \(l,r\),求 \(\sum\limits_{i=l}^r (-1)^i\times i\). 数据范围:\(1\leqslant t\leqslant 10^3,1\leqslant l\leqslant r\leqslant 10^9\). Solution 建议先去做 CF486A,然后我们可以得知 \(\sum\limits_{i=1}^n (-1)^i\times i=\begin{cases}\dfrac{i}{2}&…

A. Petya and Origamitime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputPetya is having a party soon, and he has decided to invite his n friends. He wants to make invitations in the form of origami. Fo…

A. Petya and Origami Water. #include <bits/stdc++.h> using namespace std; #define ll long long ll n, k; ll Get(ll x) { ? (x * n) / k : (x * n) / k + ; } int main() { while (scanf("%lld%lld", &n, &k) != EOF) { ll res = Get() + Get()…

A. Petya and Origami time limit per test  1 second   memory limit per test  256 megabytes input standard input output standard output Petya is having a party soon, and he has decided to invite his nn friends. He wants to make invitations in the form…

题解 CF1080A [Petya and Origami] 这道题其实要我们求的就是 \[\lceil 2*n/k \rceil + \lceil 5*n/k \rceil + \lceil 8*n/k \rceil\] 然后就做完了 # include <bits/stdc++.h> # define ll long long int main() { ll n, k; scanf("%lld%lld", &n, &k); ll ans = ((2 *…

这场比赛手速场+数学场,像我这样读题都读不大懂的蒟蒻表示呵呵呵. 第四题搞了半天,大概想出来了,但来不及(中途家里网炸了)查错,于是我交了两次丢了100分.幸亏这次没有掉rating. 比赛传送门:https://codeforces.com/contest/1080. A.Petya and Origami 题意:Petya要发出n张邀请函,每张请函需要2张红纸,5张绿纸,8张蓝纸.现在商店里有一些不同颜色的笔记本,每本中有k张颜色相同的纸,求最少要买几本笔记本. 这题就是一道模拟题,算出每种…

出现这种情况,例如:我在获取相册图片后,直接present到另一个页面,但是上一个页面可能还未dismiss,所以,要在获取相册图片的dismiss方法的complete的block里面写获取图片及跳转的方法!!!…

find your present (2) Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 21948    Accepted Submission(s): 8671 Problem Description In the new year party, everybody will get a "special present"…

HTTP Status 400 - Required String parameter 'userName' is not present 错误 先mark  有时间详细写 参考链接: https://yq.aliyun.com/articles/29107…

虚拟机Vmware上克隆了一个Red Hat Enterprise Linx启动时发现找不到网卡,如下所示,如果你在命令窗口启动网络服务就会遇到"Device eth0 does not seem to be present, delaying initialization"错误 关于这个错误,搜索了一下网上的资料,发现还蛮多人遇到过这类错误,了解了一下错误产生的原因和解决方案   错误原因: 克隆的Linux系统在新的机器上运行,新服务器网卡物理地址已经改变.而/etc/udev/r…

@RequestParam jQuery调用方式: deleteFile: function(filePath) { return ajax({ method: 'POST', url: '/cm/soft/package/package/deleteFile', data: { fileDir: filePath } }); }, 后台java controller形式 public BaseResultVO deleteFile(@RequestParam("fileDir") S…

Device eth0 does not seem to be present”解决办法 : 用ifconfig查看发现缺少eth0,只有lo:用ifconfig -a查看发现多出了eth1的信息. 解决办法1: # mv /etc/sysconfig/network-scripts/ifcfg-eth0  /etcsysconfig/network-scripts/ifcfg-eth1 将eth0的mac地址改为eth1的mac地址,同时改变其DEVICE名称为eth1,再重启网络即可. 解决…

问题: XMLHttpRequest cannot load http://v.xxx.com. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:63342' is therefore not allowed access. test.html:1 Resource interpreted as Script but transferred…

js跨域访问提示错误:XMLHttpRequest cannot load http://...... No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. 解决方法: 1.如果请求的url是aspx页面,则需要在aspx页面中添加代码:Response.AddHeader("Access-Contro…

sudo: no tty present and no askpass program specified 2012-11-30 09:30 5040人阅读 评论(1) 收藏 举报 修改sudo配置文件,直接键如visudo命令编辑配置文件: 1. 注释Defaults requirettyDefaults requiretty修改为 #Defaults requiretty, 表示不需要控制终端.否则会出现sudo: sorry, you must have a tty to run sudo…

Device eth0 does not seem to be present... 出现这个问题基本上是因为虚拟机是克隆的导致机器的mac网卡不一致,所以系统识别网卡失败:…

Device eth0 does not seem to be present,delaying initialization. 网上搜索后才发现原因所在:原来vmware在复制了虚拟机后会自动生成一个新的网卡设备供该虚拟机使用,比如 原先的网卡是eth0,复制虚拟机后后就会增加eth1.但是由于没有生成相应的/etc/sysconfig/network-scripts /ifcfg-eth1文件,导致网络连接失败,这个应该是vmware的一个bug. 查看网卡配置文件/etc/udev/rul…

系统安装Tomcat版本为:tomcat8,登录时报错"An invalid character [32] was present in the Cookie value" 处理方法将Tomcat降级为:tomcat7后登录正常.…

.nil? , .empty?, .blank? .present? 的区别 首先这三个都是判空的. 而 .nil? 和 .empty? 是ruby的方法. .blank? 是rails的方法 .nil?       判断对象是否存在(nil).不存在的对象都是nil的 .empty?  对象已经存在,判断是否为空字段,比如一个字符串是否为空串,或者一个数组中是否有值.有点像判断长度是否为零,呵呵 .blank?   相当于同时满足 .nil? 和 .empty? .railsAPI中的解释是如…

php调用shell脚本的svnup.php文件内容: <?set_time_limit(0);//$output = array();$ret = 0;exec("/usr/bin/sudo /data0/shell/svnvp.sh", $output, $ret);echo "Result:{$ret}";print_r($output);?> /data0/shell/svnvp.sh是更新的脚本,主要内容是svn up. 还需要修改sudo配置…

今天在复制vmware的时候 出现网卡无法启动 报错显示 Device eth0 does not seem to be present, delaying initialization. 这个错误原因是因为 复制的VM和源VM的mac一致,但是新VM并非这个mac了 查看/etc/udev/rules.d/70-persistent-net.rules 下的mac ,将eth0的mac手动修改一样但是并未生效 所以直接删除掉eth0下的mac的那一行配置 以及/etc/udev/rules.d…

当我想从一个VC跳转到另一个VC的时候,一般会用 - (void)presentViewController:(UIViewController *)viewControllerToPresent animated: (BOOL)flag completion:(void (^)(void))completion;当然也可以用导航push. 有时会遇到了此类警告:Warning: Attempt to present on whose view is not in the window hier…

今天做一个AJAX案例时,浏览器监控到如下错误: XMLHttpRequest cannot load http://54.169.69.60:8081/process_message. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://54.169.69.60' is therefore not allowed access. 网站地址是 http://54.…

Codeforces Round #262 (Div. 2) C C - Present C. Present time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Little beaver is a beginner programmer, so informatics is his favorite subject. Soon…

在给 tableViewCell 添加长按手势弹出一个 popViewController 的时候,遇到的这个变态问题: Warning: Attempt to present <UINavigationController: 0x15f259c00>  on <RepoDetailViewController: 0x160271400> which is already presenting (null) 我的solution : 不使用手势去运行此方法.换用了button的ad…

push与present都可以推出新的界面.present与dismiss对应,push和pop对应.present只能逐级返回,push所有视图由视图栈控制,可以返回上一级,也可以返回到根vc,其他vc.present一般用于不同业务界面的切换,push一般用于同一业务不同界面之间的切换. pop一共分为两类, pop是navigationController的方法.第一类就是,直接返回到上一层.[self.navigationController popViewControllerAnima…

转自:http://blog.sina.com.cn/s/blog_77126fa501018s3d.html vmlite虚拟机启动出错,就把这个虚拟机删除掉重新建立,系统虚拟硬盘使用之前的,启动系统后不能上网,通过ifconfig查看网卡没启动,遂启动网卡服务,但是出错,就是:device eth0 does not seem to be present, delaying initialization,然后想到是不是ifcfg-eth0的配置文件里保存了以前的MAC地址,就把这一行删除掉在…

ifconfig...没有看到eth0..然后重启网卡又报下面错误. 故障现象: service network restartShutting down loopback insterface:                                                                                                     [  OK  ]Bringing up loopback insterface:           …