Cyclic Tour                                                                                Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)                                                                            …

Cyclic Tour Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)Total Submission(s): 1688    Accepted Submission(s): 859 Problem Description There are N cities in our country, and M one-way roads connecting them. Now Li…

题目大概说给一张有向图,每条边都有权值,要选若干条边使其形成若干个环且图上各个点都属于且只属于其中一个环,问选的边的最少权值和是多少. 各点出度=入度=1的图是若干个环,考虑用最小费用最大流: 每个点拆成两点u和u' 源点向u连容量1费用0的边,表示这个点的出度最多为1 u'向汇点连容量1费用0的边,表示这个点的入度最多为1 对于原图上任何一条有向边<a,b,c>,a向b'连容量1费用c的边,选择这条边后a的出度+1,b的入度+1,费用+c 这样跑最小费用最大流,如果没满流就无解,否则MCMF…

最小权值环覆盖问题:用几个环把所有点覆盖,求所选取的边最小的权值之和. 拆点思想+求最小转求最大+KM算法 #include <cstdlib> #include <cstdio> #include <cmath> #include <cstring> #include <algorithm> #include <fstream> #include <iostream> #define rep(i, l, r) for(i…

题意: 给出n个城市和m条路,每个城市只能经过一次,想要旅游所有的城市,求需要的最小花费(路径的长度). 分析: 做题之前,首先要知道什么是完美匹配.不然题目做了却不知道为什么可以用这个方法来做.完美匹配{X,Y| E},X.Y集合都有n个点(必须相等),它们必须一对一的匹配,并且所有点都要匹配. 对于此题,每个点都有且只有走一次.把每个点都拆为 i与 i'两个点,i值负责出边(就是i点只有出度),i'负责入边.这样就有了两个集合.集合内的点不会有联系.集合之间的点有联系,但是最后只有是一一对应…

Cyclic Tour Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)Total Submission(s): 1399    Accepted Submission(s): 712 Problem Description There are N cities in our country, and M one-way roads connecting them. Now Li…

链接:http://acm.hdu.edu.cn/showproblem.php?pid=1853 Cyclic Tour Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others) Total Submission(s): 1904    Accepted Submission(s): 951 Problem Description There are N cities in our c…

Cyclic Tour Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)Total Submission(s): 1197    Accepted Submission(s): 626 Problem Description There are N cities in our country, and M one-way roads connecting them. Now Li…

Cyclic Tour Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/65535 K (Java/Others)Total Submission(s): 2399    Accepted Submission(s): 1231 Problem Description There are N cities in our country, and M one-way roads connecting them. Now L…

题目传送门 /* KM: 相比HDOJ_1533,多了重边的处理,还有完美匹配的判定方法 */ #include <cstdio> #include <cmath> #include <algorithm> #include <cstring> using namespace std; ; const int INF = 0x3f3f3f3f; int x[MAXN], y[MAXN]; int w[MAXN][MAXN]; int visx[MAXN],…