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…

dinic版本 感觉dinic算法好帅,比Edmonds-Karp算法不知高到哪里去了 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. Th…

题意:1是源点,m是汇点,求出来最大流量,没什么好说的就是练习最大流的模板题 ************************************************************** 先用Edmonds-Karp的算法做一下试试吧重边贡献了 1W,要加上所有的重边才算是两点间最大流量 *************************************************************************************************…

#include<stdio.h> #include<string.h> #define N 300 #define inf 0x7fffffff #include<queue> using namespace std; struct node {   int u,v,w,next; }bian[N*4]; int head[N],yong,d[N],s,t; void addedge(int u,int v,int w) {    bian[yong].u=u;  …

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…

链接: http://poj.org/problem?id=1273 代码: //Dinic #include<stdio.h> #include<string.h> #include<queue> #include<algorithm> using namespace std; ; ; struct Edge { int v, flow, next; }edge[MAXN]; int Head[MAXN], cnt; int Layer[MAXN]; vo…

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…

Description 现在小朋友们最喜欢的"喜羊羊与灰太狼",话说灰太狼抓羊不到,但抓兔子还是比较在行的, 而且现在的兔子还比较笨,它们只有两个窝,现在你做为狼王,面对下面这样一个网格的地形: 左上角点为(1,1),右下角点为(N,M)(上图中N=4,M=5).有以下三种类型的道路  1:(x,y)<==>(x+1,y)  2:(x,y)<==>(x,y+1)  3:(x,y)<==>(x+1,y+1)  道路上的权值表示这条路上最多能够通过的兔子…

找了好久这两个的区别...UVA820 WA了 好多次.不过以后就做模板了,可以求任意两点之间的最大流. UVA 是无向图,因此可能有重边,POJ 1273是有向图,而且是单源点求最大流,因此改模板的时候注意一下. 而且我居然犯了更愚蠢的错误,以为重边的时候需要选最大的,正解应该是累加.... #include<stdio.h> #include<queue> #include<string.h> #define INF 999999 using namespace s…

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…

Language: Default Dual Core CPU Time Limit: 15000MS   Memory Limit: 131072K Total Submissions: 19321   Accepted: 8372 Case Time Limit: 5000MS Description As more and more computers are equipped with dual core CPU, SetagLilb, the Chief Technology Offi…

http://poj.org/problem?id=1273 这道题很值得反思,弄了一下午,交上去先是一直编译错误,而在本地运行没有问题, 原因可能是oj的编译器版本老旧不支持这样的写法 G[from].push_back((edge){to,cap,G[to].size()}); G[to].push_back((edge){from,0,G[from].size() - 1}); 这两句交上去是不能通过的,不知道网上很多人这样子贴出代码是怎样通过的(‘白书’的模板有问题的) 如果是照着‘白书…

网络流模板题. ========================================================================================================== #include<cstdio> #include<cstring> #include<iostream> #include<algorithm> #include<cmath> #include<queue>…

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…

链接: http://poj.org/problem?id=1273 Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 63763   Accepted: 24613 Description Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This m…

就是普通的网络流问题,想试试新学的dinic算法,这个算法暑假就开始看国家集训队论文了,之前一直都只用没效率的EK算法,真正学会这个算法还是开学后白书上的描述:dinic算法就是不断用BFS构建层次图然后用DFS寻找增广.然后就是一下午的WA ,除了第一次调dinic的问题外,这道题竟然有多组数据!!!看discuss里好像还有重边的问题,可我用的邻接表有效避免了这个问题~~ #include <iostream> #include <cstdio> #include<str…

https://www.cnblogs.com/137shoebills/p/9100790.html http://poj.org/problem?id=2987 之前写过这道题,码一个dinic的最大流板子. 经典问题,选了一个点就有些点必须选,输出使选出的点的权值和最大的最少点数,并输出该权值和. 建图就是s向权值为正的点连流量为val的边,权值为负的点向t连流量为-val的边,所有的权值和-最大流就是答案. 类似于https://www.cnblogs.com/137shoebills/…

B - Dining Time Limit:2000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Practice POJ 3281 Appoint description:   Description Cows are such finicky eaters. Each cow has a preference for certain foods and drinks, and she w…

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…

点击打开链接 Power Network Time Limit: 2000MS   Memory Limit: 32768K Total Submissions: 20903   Accepted: 10960 Description A power network consists of nodes (power stations, consumers and dispatchers) connected by power transport lines. A node u may be su…

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…

#include<cstring> #include<cstdio> #define FOR(i,f_start,f_end) for(int i=f_startl;i<=f_end;i++) #define MS(arr,arr_value) memset(arr,arr_value,sizeof(arr)) ; ; int size; int n; const int inf=0x3f3f3f3f; using namespace std; int head[maxn];…

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…

#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()…

题意: 农场主有f种食物,d种饮料,n头牛. 接下来的n行每行第一个数代表第i头牛喜欢吃的食物数量,和第i头牛喜欢喝的饮料数目. 接下来分别是喜欢的食物和饮料的编号. 求解:农场主最多能保证几头牛同时能吃到喜欢的食物和喜欢的饮料. 思路: 从源点到每种食物加流量为1的边,保证每种食物只能被吃一次. 将每头牛分为两个点,连一条流量为1的边,保证每头牛最多只能吃一份食物喝一份饮料. 将每种饮料和汇点都进行连接,同样流量为1. 将牛喜欢的食物和牛进行连边流量为1,将另一组代表牛的点和喜欢的饮料进行连边…

watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvbmlrZTBnb29k/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" style="font-family:宋体"> Language: Default Dining Time Limit: 2000MS   Memory Limit: 65536K Total Submis…

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…

链接 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 draina…

#include<cstdio> #include<iostream> #include<cstring> #include<queue> #define INF 9999999 #define M 330 using namespace std; int maxflow,pre[M],map[M][M],n,m; void Flow(int start,int end) { ) { queue<int> p; int minflow=INF;…

Drainage Ditches Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 74480   Accepted: 28953 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…