go

2018 ACM-ICPC World Finals

由 久未见 提交于 2021-01-04 08:50:07
2018 ACM-ICPC World Finals - Beijing A. Catch the Plane $dp[v_i,t_i]$表示时刻$t_i$在$v_i$点，到达终点的最大概率，那么转移方程为： $dp[(v_i,t_i)] = max(P_{ij}*dp[(v_{j+1},t_{j+1})] + (1-Pij)*dp[(v_{i+1},t_{i+1})])$ $dp[(v_i,t_i)] = max(dp[v_{i+1},t_{i+1}])$ 其中$(v_i,t_i)$的一个后继状态为$(v_j,t_j)$两个状态之间的转移概率为$P_{ij}$，第一种转移：沿$P_{ij}$这个方向转移，以及继续留在这个点等待下次转移($(v_{i+1},t_{i+1})$为同一位置下与$t_i$最接近的下一个时间)；第二种转移是：直接选择继续等待的概率。想出这些后，以为可以愉快的ac了。然而调到早上7点。。。才弄好 问题一：%I64d读1e18，蜜汁爆了，换了几个编译器才发现。。。 问题二：为简化代码省略了讨论，导致后面一个点wa 问题三：起点和终点要单独加进去，导致后面一个点wa #include <bits/stdc++.h> #define rep(i,a,b) for(int i=a;i<=b;++i) #define pb push_back typedef long

Setting os.Mkdir permissions

由 梦想的初衷 提交于 2021-01-04 06:28:06
问题 I'm trying to create directories with certain permissions using os.Mkdir but I cannot make it work, for some reason. My test program is: package main import ( "log" "os" ) func main() { err := os.Mkdir("testdir", 0775) if err != nil { log.Print(err) } } However, the created directory has the default 0755 permissions: drwxr-xr-x 2 user user 4096 Jan 10 10:14 testdir A chmod from the shell works just fine, so I'm not sure why the Go program is not working. 回答1: When creating a file, Unix-like

Setting os.Mkdir permissions

由 半腔热情 提交于 2021-01-04 06:26:29
问题 I'm trying to create directories with certain permissions using os.Mkdir but I cannot make it work, for some reason. My test program is: package main import ( "log" "os" ) func main() { err := os.Mkdir("testdir", 0775) if err != nil { log.Print(err) } } However, the created directory has the default 0755 permissions: drwxr-xr-x 2 user user 4096 Jan 10 10:14 testdir A chmod from the shell works just fine, so I'm not sure why the Go program is not working. 回答1: When creating a file, Unix-like

Setting os.Mkdir permissions

由 不羁的心 提交于 2021-01-04 06:25:50
问题 I'm trying to create directories with certain permissions using os.Mkdir but I cannot make it work, for some reason. My test program is: package main import ( "log" "os" ) func main() { err := os.Mkdir("testdir", 0775) if err != nil { log.Print(err) } } However, the created directory has the default 0755 permissions: drwxr-xr-x 2 user user 4096 Jan 10 10:14 testdir A chmod from the shell works just fine, so I'm not sure why the Go program is not working. 回答1: When creating a file, Unix-like

Setting os.Mkdir permissions

由 女生的网名这么多〃 提交于 2021-01-04 06:24:52
问题 I'm trying to create directories with certain permissions using os.Mkdir but I cannot make it work, for some reason. My test program is: package main import ( "log" "os" ) func main() { err := os.Mkdir("testdir", 0775) if err != nil { log.Print(err) } } However, the created directory has the default 0755 permissions: drwxr-xr-x 2 user user 4096 Jan 10 10:14 testdir A chmod from the shell works just fine, so I'm not sure why the Go program is not working. 回答1: When creating a file, Unix-like

What is Edge Computing

由 我们两清 提交于 2021-01-03 17:21:17
What is Edge Computing The contribution of Edge Computing 推动边缘计算快速发展的四大因素： • 低时延 – 为满足低时延的要求，靠近业务现场的边缘构建解决方案，减少业务处理时延 • 海量数据 – 物联网时代边缘数据爆炸性增长，全部上云成本高昂，数据在本地进行分析和过滤，节省带宽 • 隐私安全 – 数据涉及到企业生产和经营活动安全，在边缘处理企业保密信息和个人隐私 • 本地自治 – 不依赖云端的离线处理能力和自我恢复能力 What is KubeEdge 1. 基于k8s构建边缘计算平台 2. 云端基于k8s master，边缘节点对k8s进行裁剪，轻量化kubelet，去掉其内置的存储驱动，同时选用生命周期管理的模块 3. 致力于将Kubernetes的能力拓展到边缘 4. 基于Kubernetes构建，100%兼容k8s API Core Idea 云边协同 • 云、边采用双向多路复用消息通道，支持边缘节点位于私有网络 • 采用Websocket + 消息封装，大幅减少通信压力，高时延下仍可正常工作 边缘离线自治 • 节点元数据持久化，实现节点级离线自治 • 节点故障恢复无需List-watch，降低网络压力，快速ready 极致轻量 • 重组Kubelet功能模块，极致轻量化（约10mb内存占用） 移除内嵌存储驱动

“12306”是如何支撑百万QPS的？

由 陌路散爱 提交于 2021-01-03 15:42:42
点击 上方“ 程序猿技术大咖 ”，选择“ 关注公众号 ”， 一起共进步！ 每到节假日期间，一二线城市返乡、外出游玩的人们几乎都面临着一个问题：抢火车票！ 来源:http://rrd.me/eE8ty 12306 抢票，极限并发带来的思考 虽然现在大多数情况下都能订到票，但是放票瞬间即无票的场景，相信大家都深有体会。 尤其是春节期间，大家不仅使用 12306，还会考虑“智行”和其他的抢票软件，全国上下几亿人在这段时间都在抢票。 “12306 服务”承受着这个世界上任何秒杀系统都无法超越的 QPS，上百万的并发再正常不过了！ 笔者专门研究了一下“12306”的服务端架构，学习到了其系统设计上很多亮点，在这里和大家分享一下并模拟一个例子：如何在 100 万人同时抢 1 万张火车票时，系统提供正常、稳定的服务。 Github代码地址： https: //github.com/GuoZhaoran/spikeSystem 大型高并发系统架构 高并发的系统架构都会采用分布式集群部署，服务上层有着层层负载均衡，并提供各种容灾手段（双火机房、节点容错、服务器灾备等 ） 保证系统的高可用，流量也会根据不同的负载能力和配置策略均衡到不同的服务器上。 下边是一个简单的示意图： 负载均衡简介 上图中描述了用户请求到服务器经历了三层的负载均衡，下边分别简单介绍一下这三种负载均衡。 ①OSPF

GORM create record that might already exist

由 ▼魔方 西西 提交于 2021-01-03 05:30:06
问题 I'm using gorm with postgres in my Go app. I want to create a new user in the database, but there is a good chance that that user will already exist. If so, I want to not do anything with the database, but I want know about it so I can tell the user. The good news is, that's already what gorm.Create(..) does. Trying to create a record with a duplicate unique key will return an error. There are two problems: I want better error messages. I want to write custom user-facing error messages that

Convert a byte array to a string array [duplicate]

由 那年仲夏 提交于 2021-01-02 18:43:37
问题 This question already has answers here : Convert a byte to a string in Go (5 answers) Closed 2 years ago . In the following method, I attempted to redefine the string method on the IPAddr type by appending bytes to an array of string type IPAddr [4]byte func (ip IPAddr) String() string { var s []string for _, i := range ip { s = append(s, i) } return fmt.Sprintf(strings.Join(s, ".")) } cannot use i (type byte) as type string in append playground 回答1: Since your type is an array with a small

Convert a byte array to a string array [duplicate]

由 久未见 提交于 2021-01-02 18:27:11
问题 This question already has answers here : Convert a byte to a string in Go (5 answers) Closed 2 years ago . In the following method, I attempted to redefine the string method on the IPAddr type by appending bytes to an array of string type IPAddr [4]byte func (ip IPAddr) String() string { var s []string for _, i := range ip { s = append(s, i) } return fmt.Sprintf(strings.Join(s, ".")) } cannot use i (type byte) as type string in append playground 回答1: Since your type is an array with a small
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