Problem Description Are you interested in pets? There is a very famous pets shop in the center of the ACM city. There are totally m pets in the shop, numbered from 1 to m. One day, there are n customers in the shop, which are numbered from 1 to n. In…

Description Are you interested in pets? There is a very famous pets shop in the center of the ACM city. There are totally m pets in the shop, numbered from 1 to m. One day, there are n customers in the shop, which are numbered from 1 to n. In order t…

Are you interested in pets? There is a very famous pets shop in the center of the ACM city. There are totally m pets in the shop, numbered from 1 to m. One day, there are n customers in the shop, which are numbered from 1 to n. In order to sell pets…

这道题的建模真的非常的秀, 非常牛逼. 先讲建模过程.源点到每一行连一条弧, 容量为这一行的和减去列数, 然后每一列到汇点连一条弧, 容量为这一列 的和减去行数, 然后每一行和列之间连一条弧, 容量为19.然后求最大流, 最后矩阵中每一个元素的值就是其所在 列和行所连的弧的容量加1. 让我来解释一下.设每一个行为xi, 每一列为yi.在网络流中, 每一个xi都有多条弧连到所有的yi, 在矩形当中 每一行的每一个元素都是每一列的一部分.在网络流中,对于一个yi来说,  所有的xi都有一条弧连到这个…

题目链接 有一个n*m的图, 里面有q个人, 每个点只能走一次, 问这q个人是否都能够走出这个图. 对于每个人, 建边(s, u, 1), 对于每个边界的格子, 建边(u', t, 1), 对于其他格子, 建边(u, u', 1), 以及(u', v, 1), v是它四周的格子. 对于求出的最大流, 如果等于人数, 则可以走出. #include<bits/stdc++.h> using namespace std; #define pb(x) push_back(x) #define ll…

题意:n个插座,m个设备及其插头类型,k种转换器,没有转换器的情况下插头只能插到类型名称相同的插座中,问最少剩几个不匹配的设备 lrj紫书里面讲得挺好的. 先跑一遍floyd,看看插头类型a能否转换为b 然后构造网络 源点为0, 汇点为n + m + 1,源点连插头 容量为1,插座连汇点,容量为1 插头和插座能互相转换的容量为INF,跑一遍最大流 m - 最大流就是答案 顺便粘一下dinic的板子 #include <bits/stdc++.h> using namespace std; in…

这道题改了两天-- 因为这道题和节点有关, 所以就用拆点法解决节点的容量问题. 节点拆成两个点, 连一条弧容量为1, 表示只能经过一次. 然后图中的弧容量无限. 然后求最小割, 即最大流, 即为答案. 固定一个源点, 然后枚举汇点, 然后求最小的最小割就ok了. 这里的拆点法连边的时候是拆出来的点连上原来的点. 同时起点是起点拆出来的点终点是原来的点, 因为这起点和终点是可以经过很多次 的. 所以总结一下拆点法(解决每个节点只能经过一次的问题) (1)开始初始化每个点拆成两个点, 连一条弧, 容…

设一个源点, 到所有设备连一条弧, 容量为1, 然后设一个汇点, 所有插座到汇点连弧, 容量为1, 然后 转换器也连一条弧, 容量为1. 最后最大流就是答案.其中注意节点数要开大一些. #include<cstdio> #include<queue> #include<iostream> #include<vector> #include<algorithm> #include<cstring> #define REP(i, a, b…

UVA 10480 Sabotage (网络流,最大流,最小割) Description The regime of a small but wealthy dictatorship has been abruptly overthrown by an unexpected rebel-lion. Because of the enormous disturbances this is causing in world economy, an imperialist military super…

POJ 1087 A Plug for UNIX / HDU 1526 A Plug for UNIX / ZOJ 1157 A Plug for UNIX / UVA 753 A Plug for UNIX / UVAlive 5418 A Plug for UNIX / SCU 1671 A Plug for UNIX (网络流) Description You are in charge of setting up the press room for the inaugural meet…