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由题意可知，本意要求的是二分图的最小点覆盖集问题，即最小的顶点集合，“覆盖”所有的边，可以转化成二分图的最大匹配问题。 二分图的最小点覆盖数 == 最大匹配数。

题意：有N个城市以及连接这些城市的M条无向边，其中城市1是啤酒产地。给出N-1个数字，分别表示每个城市里啤酒每桶的价格（城市1不算），我们可以认为这N-1个城市对啤酒的需求是没有限制的即 无限大。已知每条无向边最多可以运送啤酒的桶数 和运送每桶的花销，问你从城市1出发卖啤酒可以得到的最大收益。解析：算是比较好像的费用流了，但要注意。每次SPFA找到可以从源点到汇点的最长路后，我

MissileTime Limit: 2 Seconds      Memory Limit: 65536 KB You control N missile launching towers. Every tower has enough missiles, but for each tower only one missile can be launch at the s

Power NetworkTime Limit: 2000MS Memory Limit: 32768KTotal Submissions: 25108 Accepted: 13077DescriptionA power network consists of nodes (power stations, consum

Burning BridgesTime Limit: 5 Seconds      Memory Limit: 32768 KB Ferry Kingdom is a nice little country located on N islands that are connected by M bridges. All bridges are very beautiful

The Exchange of ItemsTime Limit: 2 Seconds      Memory Limit: 65536 KB Bob lives in an ancient village, where transactions are done by one item exchange with another. Bob is very clever an

Air RaidTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 7451 Accepted: 4434DescriptionConsider a town where all the streets are one-way and each stree

Girls and BoysTime Limit: 5000MS Memory Limit: 10000KTotal Submissions: 11134 Accepted: 4981DescriptionIn the second year of the university somebody started a s

How Many Shortest PathTime Limit: 10 Seconds      Memory Limit: 32768 KB Given a weighted directed graph, we define the shortest path as the path who has the smallest length among all the

NetworkingTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 7259 Accepted: 3941DescriptionYou are assigned to design network connections between certain

题目大意：给n个点，m条边。求一棵生成树，并且满足任意两点之间的距离的最大值最小。输出这个最大值，然后输出树的边的数量，最后输出树的每条边。题目思路：对于一个生成树来说，它的最大边满足在所有的生成树的最大边里最小，这其实就是一颗最小生成树。#include #include #include #include #define maxn 1010#define maxm 200

Building a Space StationTime Limit: 1000MS Memory Limit: 30000KTotal Submissions: 5655 Accepted: 2848DescriptionYou are a member of the space station engineerin

Uncle Tom's Inherited LandTime Limit: 2 Seconds      Memory Limit: 65536 KB Your old uncle Tom inherited a piece of land from his great-great-uncle. Originally, the property had been in th

COURSESTime Limit: 1000MS Memory Limit: 10000KTotal Submissions: 19581 Accepted: 7709DescriptionConsider a group of N students and P courses. Each student visit

Place the RobotsTime Limit: 5 Seconds      Memory Limit: 32768 KB Robert is a famous engineer. One day he was given a task by his boss. The background of the task was the following:Giv

题意：给你N个点、M条无向边以及边的权值，又给你源点A和汇点B。问你A到B的最小割是否唯一解析：1、我们先对原图求一次最大流2、对残留网络，我们从S开始，找到所有所有S能到达的点；再从T开始，找出所有能到达T的点。3、判断原网络中是否还有没有访问到的点，如果没有，则唯一，否者，不唯一！