#include <iostream> #include <queue> using namespace std; ][]; ]; //路径上每个节点的前驱节点 ]; int n,m; //m是顶点数目,顶点编号从1开始 1是源,m是汇, n是 边数 int Augment() { int v; int i; deque<int> q; memset(Prev,,sizeof(Prev)); memset(Visited,,sizeof(Visited)); Prev[…

                                                         Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 69983   Accepted: 27151 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorit…

Description 给图,求最大流 最大流模板题,这里用dinic Code #include <cstdio> #include <cstring> #include <algorithm> #define Inf 0x7fffffff #define N 210 using namespace std; int g[N][N],d[N],q[N*10],h,t; int n,m,Ans,tmp; bool Bfs(){ memset(d,-1,sizeof(d)…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 76000   Accepted: 29530 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 78671   Accepted: 30687 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by…

题目链接: Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 67475   Accepted: 26075 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is cover…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 68414   Accepted: 26487 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by…

Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time to regrow. Thus, Farmer John has built a set of drainage…

A - Drainage Ditches Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u   Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by wa…

一.题面 Drainage Ditches 二.分析 网络流的裸题. 1 Edmonds-Karp算法 求解网络流其实就是一个不断找增广路,然后每次找到一条增广路后更新残余网络的一个过程. EK算法主要就是用bfs去找增广路,然后不断更新残余网络得到最终答案. 2 Dinic算法 对于Ford-Fulkerson和Edmonds-Karp算法,求解网络流都是一次次用DFS或者BFS,这其实是很费时的,Dinic相当于就是一次BFS然后DFS求解出多条增广路. 3 ISAP 三.AC代码 1 //…

Drainage Ditches Time Limit: 1000MS Memory Limit: 10000K Total Submissions: 65146 Accepted: 25112 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by wate…

Drainage Ditches Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 65536/32768K (Java/Other) Total Submission(s) : 5   Accepted Submission(s) : 3 Font: Times New Roman | Verdana | Georgia Font Size: ← → Problem Description Every time it rains on…

Drainage Ditches Time Limit: 1000MS Memory Limit: 10000K Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time…

http://poj.org/problem?id=1273 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time to regrow. Thus, Farmer Jo…

网络流一直没学,来学一波网络流. https://vjudge.net/problem/POJ-1273 题意:给定点数,边数,源点,汇点,每条边容量,求最大流. 解法:EK或dinic. EK:每次增广用bfs选择一条从源到汇具有最少边数的增广路径,然后找出该路径容量最小的边,就是此次增加的流量,然后沿该路径增加反向边,同时修改每条边的容量,重复上述过程直到找不到增广路(即minFlow = 0)为止. dinic: 每次bfs从源点到汇点分层(层数是源点到它最少要经过的边数),然后dfs从源…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1532 思路分析:问题为最大网络流问题,给定一个有向图,需要求解该有向图的最大网络流,使用EdmondsKarp算法求解: 需要注意输入的边中可能有重边的存在: 代码如下: #include <queue> #include <vector> #include <cstdio> #include <climits> #include <cstring>…

题目链接 网络流入门@_@,此处本人用的刘汝佳的Dinic模板 #include<bits/stdc++.h> using namespace std; const int INF = 0x3f3f3f3f; struct Edge { int from,to,cap,flow; }; int n,s,t,m; struct Dinic { , M = ; //N对应点数 vector<Edge> edges; vector<int> G[N]; bool vis[N]…

一直不明白为什么我的耗时几百毫秒,明明差不多的程序啊,我改来改去还是几百毫秒....一个小时后:明白了,原来把最大值0x3f(77)取0x3f3f3f3f就把时间缩短为16ms了.可是为什么原来那样没有WA呢?哦,明白了,因为最大值写小了,dicnic会多跑几遍.嗯顺便:0x3f3f3f3f也就是1061109567,也就是10^9级别的,是一个很大的数,而且加上一个10^9级别以下的数字也不会溢出.所以很多时候最大值取这个会比较好.最大的int是0x7fffffff,可以用常量INT_MAX…

POJ 1273给出M条边,N个点,求源点1到汇点N的最大流量. 本文主要就是附上dinic的模板,供以后参考. #include <iostream> #include <stdio.h> #include <algorithm> #include <queue> #include <string.h> /* POJ 1273 dinic算法模板 边是有向的,而且存在重边,且这里重边不是取MAX,而是累加和 */ using namespace…

解题关键:最大流裸题 #include<cstdio> #include<cstring> #include<algorithm> #include<cstdlib> #include<cmath> #include<iostream> #include<queue> #include<vector> #define inf 0x3f3f3f3f #define MAX_V 252 using namespac…

http://poj.org/problem?id=1273 Dinic算法 这是一道最大流的经典题 最大流尽量应该用边表,优于邻接矩阵(所以我写了邻接矩阵版的之后又写了个边表) 用了新学的Dinic算法 在每次找增广路之前先跑一遍bfs,把所有点的深度标记,按bfs记下的顺序找增广路,这条增广路上最小的边容量就是这条增广路的最大费用 跑出一条增广路之后,就开始更新现在的边剩余的容量,并建立反向边. #include<iostream> #include<cstdio> #incl…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 67387   Accepted: 26035 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by…

题目链接:poj1273 Drainage Ditches 呜呜,今天自学网络流,看了EK算法,学的晕晕的,留个简单模板题来作纪念... #include<cstdio> #include<vector> #include<queue> #include<cstring> #include<set> #include<algorithm> #define CLR(a,b) memset((a),(b),sizeof((a))) usi…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 59176   Accepted: 22723 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by…

Drainage Ditches 自己拉的专题里面没有这题,网上找博客学习网络流的时候看到闯亮学长的博客然后看到这个网络流入门题!随手一敲WA了几发看讨论区才发现坑点! 本题采用的是Edmonds-Karp算法求增广路.小白书上只介绍了这个算法,确实对于数据不刁钻的题目这个算法足以应对.大白书上的Dinic及SAP.ISAP还没有去看,以后慢慢攻克吧! 回到这个题:n条水渠,m个交点,每条水渠有一个最大容量cap,求1号交点到m号交点的最大流. 学了EK算法这题就可以裸引用了,只是注意一个坑点:…

Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time to regrow. Thus, Farmer John has built a set of drainage…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 63339   Accepted: 24434 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by…

Drainage Ditches Problem Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time to regrow. Thus, Farmer John has…

Drainage Ditches 题目抽象:给你m条边u,v,c.   n个定点,源点1,汇点n.求最大流.  最好的入门题,各种算法都可以拿来练习 (1):  一般增广路算法  ford() #include <iostream> #include <cstdio> #include <cstring> #include <cmath> #include <algorithm> #include <string> #include…

Drainage DitchesHal Burch Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time to regrow. Thus, Farmer John has built a se…