Constructing Roads Time Limit:2000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Practice POJ 2421 Appoint description:  System Crawler  (2015-05-27) Description There are N villages, which are numbered from 1 to N, and y…

There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each other. We say two village A and B are connected, if and only if there is a road between A and B, or there exists a…

最小生成树-普利姆(Prim)算法 最小生成树 概念:将给出的所有点连接起来(即从一个点可到任意一个点),且连接路径之和最小的图叫最小生成树.最小生成树属于一种树形结构(树形结构是一种特殊的图),或者说是直链型结构,因为当n个点相连,且路径和最短,那么将它们相连的路一定是n-1条. 可以利用参考一个问题理解最小生成树,有n个村庄,每个村庄之间距离不同,要求村庄之间修路,每一个村庄必须与任意一个村庄联通,如何修路最省钱(修的最短) 普利姆算法介绍 利姆(Prim)算法求最小生成树,也就是在包含n个…

Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 26694   Accepted: 11720 Description There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each other. We say two…

算法描述 lazy普利姆算法的步骤: 1.从源点s出发,遍历它的邻接表s.Adj,将所有邻接的边(crossing edges)加入优先队列Q: 2.从Q出队最轻边,将此边加入MST. 3.考察此边的两个端点,对两个端点重复第1步. 示例 从顶点0开始,遍历它的邻接表:边0-7.0-2.0-4.0-6会被加入优先队列Q. 顶点0的邻接表搜索完毕后,边0-7是最轻边,所以它会出队,并加入MST. 如下图: 边0-7出队后,开始考察边的两个端点: 顶点0已经访问过了,跳过: 顶点7还未探索,开始探索…

普利姆(Prim)算法 1. 最小生成树(又名:最小权重生成树) 概念:将给出的所有点连接起来(即从一个点可到任意一个点),且连接路径之和最小的图叫最小生成树.最小生成树属于一种树形结构(树形结构是一种特殊的图),或者说是直链型结构,因为当n个点相连,且路径和最短,那么将它们相连的路一定是n-1条. 可以利用参考一个问题理解最小生成树,有n个村庄,每个村庄之间距离不同,要求村庄之间修路,每一个村庄必须与任意一个村庄联通,如何修路最省钱(修的最短). 2. 普利姆算法介绍 利姆(Prim)算法求最…

算法描述 在普利姆算法的lazy实现中,参考:普利姆算法的lazy实现 我们现在来考虑这样一个问题: 我们将所有的边都加入了优先队列,但事实上,我们真的需要所有的边吗? 我们再回到普利姆算法的lazy实现,看一下这个问题: 当顺着顶点0的邻接表考察顶点7时,边7-2和边7-1被加入了优先队列Q. 然而,当我们开始对顶点2进行考察时: 边2-3是最轻边,我们显然不需要对边7-2和边7-1进行再次考察. 但是,由于边7-2和边7-1在对顶点2进行考察之前已经加入了优先队列Q,似乎我们对之前发生的事无…

Constructing Roads 题目链接: http://acm.hust.edu.cn/vjudge/contest/124434#problem/D Description There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each other. We say two villa…

Constructing Roads Description There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each other. We say two village A and B are connected, if and only if there is a road betw…

Constructing Roads Time Limit: 2000MS   Memory Limit: 65536K Total Submissions: 19884   Accepted: 8315 Description There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each…