题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1532 Drainage Ditches Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 18864    Accepted Submission(s): 8980 Problem Description Every time it rain…

题目网址:http://acm.hdu.edu.cn/showproblem.php?pid=1532 思路: 网络流最大流的入门题,直接套模板即可~ 注意坑点是:有重边!!读数据的时候要用“+=”替换“=”. 对网络流不熟悉的,给一篇讲解:http://www.cnblogs.com/ZJUT-jiangnan/p/3632525.html. ✧(≖ ◡ ≖✿)我是看这篇博客才入门的. 代码: #include <cstdio> #include <cstring> #inclu…

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 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 17065    Accepted Submission(s): 8066 Problem Description Every time it rains on Farmer John's fields, a pond forms over Bessie'…

题目链接:http://poj.org/problem?id=1273 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…

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…

Drainage Ditches Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 16314    Accepted Submission(s): 7748 Problem Description Every time it rains on Farmer John's fields, a pond forms over Bessie'…

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:…

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 DitchesHal Burch Time Limit 1000 ms Memory Limit 65536 kb 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…

Drainage Ditches Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 9580    Accepted Submission(s): 4541 Problem Description Every time it rains on Farmer John's fields, a pond forms over Bessie's…

题目链接:http://poj.org/problem?id=1273 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 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 9715    Accepted Submission(s): 4623 Problem Description Every time it rains on Farmer John's fields, a pond forms over Bessie's…

描述 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 ditches s…

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   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 f…

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…

题目大意:最大流的模板题...源点是0,汇点是n-1. 代码如下: # include<iostream> # include<cstdio> # include<cmath> # include<string> # include<vector> # include<list> # include<set> # include<map> # include<queue> # include<…

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…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1532 题目大意: 给出有向图以及边的最大容量,求从1到n的最大流 思路: 传送门:最大流的增广路算法 直接套用模板,用水流来理解网络流 #include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<vector> #include<queu…

这道题用dinic会超时 用E_K就没问题 注意输入数据有重边.POJ1273 dinic的复杂度为O(N*N*M)E_K的复杂度为O(N*M*M)对于这道题,复杂度是相同的. 然而dinic主要依靠Dfs寻找增广路,故而使用了太多次递归,而利用bfs寻找增广路(使用队列而不用递归)的EK等于用栈的方式实现了dinic的递归,所以 大幅提高了效率. 最大流算法的核心就是找到增广路并且增加反向边流量,理解了这个,最大流算法就很简单了. #include<iostream> #include<…

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…

最大流的第一道题,刚开始学这玩意儿,感觉好难啊!哎····· 希望慢慢地能够理解一点吧! #include<stdio.h> #include<string.h> #include<queue> using namespace std; #define inf 1000000 #define min(a,b) a<b?a:b int map[210][210],pre[210],maxf[210]; int n,m; int bfs()//搜索,截止找不到增广路…

最大流模板题 今天补最大流,先写道模板题,顺便写点对它的理解 最大流问题就是给一个幽香有向图,每一条边有容量,问若从$s$点放水,最多会有多少水流到$t$ 为了解决整个问题,第一步我们当然要找到一条路径让它达到满流的状态,这里直接xjbdfs即可 比如我们找到一条路径$1\to2\to3\to4$,流量为$2$ 但是我们有可能需要“反悔”,比如不走$2\to3$而走$2\to4$ 这时我们可以使用一些小技巧:添加反向边并更新正向边的容量 以后如果我们走了反向边就相当于是在“反悔” 我们把上述找一…

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…

练一下最大流 #include <iostream> #include <cstring> #include <cstdio> #include <queue> using namespace std; int n, m, ron[205][205], pre[205], uu, vv, ww, vis[205]; queue<int> d; int ek(){ int maxFlow=0; while(1){ memset(vis, 0, si…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1532 感觉题意不清楚,不知道是不是个人英语水平问题.本来还以为需要维护入度和出度来找源点和汇点呢,看讨论才知道1就是起点,m就是汇点..好想把代码写的工程化一点. #include <stdio.h> #include <string.h> #include <queue> #include <algorithm> using namespace std; c…

#include<cstdio> #include<algorithm> #include<cstring> #include<queue> #define N 250 #define M 250 #define INF 100000000 using namespace std; int head[N],cur[N],lev[N],ecnt=1,S,T,n,m; queue <int> q; struct adj { int nxt,v,w;…

#include<cstdio> #include<cstring> #include<algorithm> using namespace std; int n, m, S, T; ;//点数的最大值 ;//边数的最大值 const int INF = 0x3f3f3f3f; struct Edge { int to,next,cap,flow; } edge[MAXM]; //注意是MAXM int tol; int head[MAXN]; void init()…

题目背景 在农夫约翰的农场上,每逢下雨,贝茜最喜欢的三叶草地就积聚了一潭水.这意味着草地被水淹没了,并且小草要继续生长还要花相当长一段时间.因此,农夫约翰修建了一套排水系统来使贝茜的草地免除被大水淹没的烦恼(不用担心,雨水会流向附近的一条小溪).作为一名一流的技师,农夫约翰已经在每条排水沟的一端安上了控制器,这样他可以控制流入排水沟的水流量. 题目描述 农夫约翰知道每一条排水沟每分钟可以流过的水量,和排水系统的准确布局(起点为水潭而终点为小溪的一张网).需要注意的是,有些时候从一处到另一处不只有…