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…

模板题:POJ1273 EK: #include <queue> #include <cstdio> #include <cstring> #include <algorithm> using namespace std; int n,m,jy,map[305][305],c[305][305],a[305],p[305]; bool vis[305]; int M(int e) { int f=0; queue<int>q; while(1){…

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…

http://poj.org/problem?id=1273 Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions:87219   Accepted: 33916 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means…

isap模板核心代码: //d[]为距离标号数组,d[i]表示节点i到汇点的距离 //gap[]为GAP优化数组,gap[i]表示到汇点距离为i的节点个数 int dfs(int k,int flow){//flow为当前剩余流量 int i; if(k==t)return flow; ; for(i=head[k];i;i=e[i].nxt){ int v=e[i].to; ){//判断能否通过流量以及走的是否为最短路 int f=dfs(v,min(flow-sum,e[i].f));//注…

之前自己写的,以后当一个模板的基础吧,不管是最大流,最小割,二分图匹配 下面是POJ1273的一个裸题.. 1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <vector> 5 #include <queue> 6 using namespace std; 7 struct node{ 8 int to,cap,rev; 9 node(int _t…

你不能把数据规模改大点吗= =我优化都不加都过了 #include <cstdio> #define INF 2147483647 int n,m,ans,x,y,z,M; ],l[],fir[],nex[],to[],wei[]; int min(int a,int b){if(a<b) return a;else return b;} void add(int x,int y,int z){to[++M]=y;wei[M]=z;nex[M]=fir[x];fir[x]=M;} int…

基于残留网络与FF算法的改进-EK算法,核心是将一条边的单向残留容量的减少看做反向残留流量的增加. //网络流 //EK算法 //Time:16Ms Memory:348K #include<iostream> #include<cstring> #include<cstdio> #include<algorithm> #include<queue> using namespace std; #define MAX 205 #define INF…

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…

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…