d.一颗树,选最少的点覆盖所有边 s. 1.可以转成二分图的最小点覆盖来做.不过转换后要把匹配数除以2,这个待细看. 2.也可以用树形dp c.匈牙利算法(邻接表,用vector实现): /* 用STL中的vector建立邻接表实现匈牙利算法 效率比较高 处理点比较多的效率很高.1500的点都没有问题 */ #include<iostream> #include<stdio.h> #include<algorithm> #include<string.h>…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1054 题目大意:给你一棵树,选取树上最少的节点使得可以覆盖整棵树. 解题思路: 首先树肯定是二分图,因为树可以奇偶分层,从而根据二分图染色的原理可以确定树是二分图.我们可以用染色法确定出两个集合求最大匹配,也可以将边补成双向的,然后将最大匹配/2. 代码: #include<iostream> #include<cstdio> #include<cstring> #incl…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 6586    Accepted Submission(s): 3066 Problem Description Bob enjoys playing computer games, especially strategic games, but some…

Problem Description Bob enjoys playing computer games, especially strategic games, but sometimes he cannot find the solution fast enough and then he is very sad. Now he has the following problem. He must defend a medieval city, the roads of which for…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 2925    Accepted Submission(s): 1222 Problem Description Bob enjoys playing computer games, especially strategic games, but somet…

 最小点覆盖概念:选取最小的点数覆盖二分图中的所有边. 最小点覆盖 = 最大匹配数. 证明:首先假设我们求的最大匹配数为m,那么最小点覆盖必然 >= m,因为仅仅是这m条边就至少需要m个点.然后假如我们已经求得最小覆盖点集,那么在点集中每个点必然有着这样的性质,在于它相连的边里面,一定有一条边的端点不在最小点集中,因为如果连一条这样的边都没有,那这个点完全没有在最小点集的必要,我们任意选取这样的一条边,一定可以形成一个匹配,匹配数与最小点集中的点的个数相等,但现在这仅仅是一个匹配,他必然小于最大…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 4061    Accepted Submission(s): 1791 Problem Description Bob enjoys playing computer games, especially strategic games, but some…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 4697    Accepted Submission(s): 2125 Problem Description Bob enjoys playing computer games, especially strategic games, but somet…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 3806    Accepted Submission(s): 1672 Problem Description Bob enjoys playing computer games, especially strategic games, but some…

Strategic Game Time Limit: 20000/10000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 8504    Accepted Submission(s): 4094 Problem Description Bob enjoys playing computer games, especially strategic games, but some…