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…

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…

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…

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<…

#include <iostream> #include<cstdio> #include<queue> #include<cstring> using namespace std; #define INF 0xfffffff #define N 210 int cap[N][N],flow[N][N]; int pre[N],dist[N]; int ek(int sta,int end){ int i,curr,sum=0; memset(flow,0,…

#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()…

http://poj.org/problem?id=1273 Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 62708   Accepted: 24150 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means…

http://poj.org/problem? id=1273 Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 55235   Accepted: 21104 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This mean…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 63924   Accepted: 24673 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…