题意:对一个带权有向图,将所有点纳入一个或多个环中,且每个点只出现一次,求其所有环的路径之和最小值. 分析:每个点都只出现一次,那么换个思路想,每个点入度出度都为1.将一个点拆成两个点,一个作为入度点,一个作为出度点.每个入度点都和一个出度点匹配,且不为自己.那么可以将问题转化为二分图最优匹配的问题,这里我们求得是最短路径,那么建图时,把权值取反.这样最优匹配后取反就是最短的路径. #include <cstdio> #include <vector> #include <a…

Tour(dp) 给定平面上n(n<=1000)个点的坐标(按照x递增的顺序),各点x坐标不同,且均为正整数.请设计一条路线,从最左边的点出发,走到最右边的点后再返回,要求除了最左点和最右点之外每个点恰好经过一次,且路径总长度最短.两点间的长度为它们的欧几里得距离. 首先转换一下题意,可以看作找到两条不相交(除了起点终点)且总长最短的路径.这种题型有一个套路,就是让两个点再路径上模拟前进.如果用\(d(i, j)\)表示第一个人走到i,第二个人走到j,那么就不能设计出转移方程,因为不能保证两个人…

Tour Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others) Total Submission(s): 2549    Accepted Submission(s): 1257 Problem Description In the kingdom of Henryy, there are N (2 <= N <= 200) cities, with M (M <= 3000…

Tour Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others) Total Submission(s): 2299    Accepted Submission(s): 1151 Problem Description In the kingdom of Henryy, there are N (2 <= N <= 200) cities, with M (M <= 3000…

http://acm.hdu.edu.cn/showproblem.php?pid=3488 题意: 给出n个点和m条边,每条边有距离,把这n个点分成1个或多个环,且每个点只能在一个环中,保证有解. 思路: 把一个点分成两部分,1~n和n+i~2*n. 连边的情况是这样的,(src,i,1,0),(i+n,dst,1,0). 如果两个点之间相同,则(i,j+n,1,d). 其实这道题目就是选n条边,如何使得权值之和最小. 具体请参考这http://blog.csdn.net/u013480600…

Tour Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 65535/65535 K (Java/Others)Total Submission(s): 4279    Accepted Submission(s): 2041 题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=3488 Description: In the kingdom of Henryy, there are N (…

Young naturalist Bill studies ants in school. His ants feed onplant-louses that live on apple trees. Each ant colony needsits own apple tree to feed itself.Bill has a map with coordinates of n ant colonies and napple trees. He knows that ants travel…

Assignment Problem Description Last year a terrible earthquake attacked Sichuan province. About 300,000 PLA soldiers attended the rescue, also ALPCs. Our mission is to solve difficulty problems to optimization the assignment of troops. The assignment…

奔小康赚大钱 Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 5865    Accepted Submission(s): 2589 Problem Description 传说在遥远的地方有一个非常富裕的村落,有一天,村长决定进行制度改革:重新分配房子. 这可是一件大事,关系到人民的住房问题啊.村里共有n间房间,刚好有n家老百姓,考…

Free DIY Tour Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 2735    Accepted Submission(s): 889 [题目链接]http://acm.hdu.edu.cn/showproblem.php?pid=1224 [题目意思]题目是说给你一个有环的图,结点之间有路径,每个结点都有个兴趣值,现在给你起…