POJ1273_Drainage Ditches(网络流)
来源:互联网 发布:文章发布系统php源码 编辑:程序博客网 时间:2024/06/05 08:24
Drainage Ditches
Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 54887 Accepted: 20919
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 ditches so that Bessie's clover patch is never covered in water. Instead, the water is drained to a nearby stream. Being an ace engineer, Farmer John has also installed regulators at the beginning of each ditch, so he can control at what rate water flows into that ditch.
Farmer John knows not only how many gallons of water each ditch can transport per minute but also the exact layout of the ditches, which feed out of the pond and into each other and stream in a potentially complex network.
Given all this information, determine the maximum rate at which water can be transported out of the pond and into the stream. For any given ditch, water flows in only one direction, but there might be a way that water can flow in a circle.
Farmer John knows not only how many gallons of water each ditch can transport per minute but also the exact layout of the ditches, which feed out of the pond and into each other and stream in a potentially complex network.
Given all this information, determine the maximum rate at which water can be transported out of the pond and into the stream. For any given ditch, water flows in only one direction, but there might be a way that water can flow in a circle.
Input
The input includes several cases. For each case, the first line contains two space-separated integers, N (0 <= N <= 200) and M (2 <= M <= 200). N is the number of ditches that Farmer John has dug. M is the number of intersections points for those ditches. Intersection 1 is the pond. Intersection point M is the stream. Each of the following N lines contains three integers, Si, Ei, and Ci. Si and Ei (1 <= Si, Ei <= M) designate the intersections between which this ditch flows. Water will flow through this ditch from Si to Ei. Ci (0 <= Ci <= 10,000,000) is the maximum rate at which water will flow through the ditch.
Output
For each case, output a single integer, the maximum rate at which water may emptied from the pond.
Sample Input
5 41 2 401 4 202 4 202 3 303 4 10
Sample Output
50
Source
USACO 93
解题报告
听说第一发网络流要纪念一下,有模板的嫌疑,Discuss的情况都遇上了,多组忘了清零,重边忘了处理。
#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#define inf 99999999#define M 200+10using namespace std;struct edge{ int c,f;}edge[M][M];int n,m,vis[M],a[M],pre[M],f;queue<int>Q;void ford(){ while(1) { memset(pre,-1,sizeof(pre)); memset(a,-1,sizeof(a)); memset(vis,-1,sizeof(vis)); while(!Q.empty()) Q.pop(); Q.push(1); pre[1]=1; vis[1]=0; a[1]=inf; while(!Q.empty()&&vis[m]==-1) { int u=Q.front(); Q.pop(); for(int v=1;v<=m;v++) { if(vis[v]==-1) { if(edge[u][v].f<edge[u][v].c) { a[v]=min(a[u],edge[u][v].c-edge[u][v].f); vis[v]=0; pre[v]=u; Q.push(v); } else if(edge[v][u].f>0) { a[v]=min(a[u],edge[v][u].f); vis[v]=0; pre[v]=-u; Q.push(v); } } } vis[u]=1; } if(vis[m]==-1||a[m]==0) break; int k1=m,k2=abs(pre[k1]); int aaa=a[m]; while(1) { edge[k2][k1].f+=aaa; edge[k1][k2].f-=aaa; if(k2==1)break; k1=k2;k2=abs(pre[k2]); } f+=a[m]; }}int main(){ int i,j,u,v,w; while(~scanf("%d%d",&n,&m)) { f=0; memset(edge,0,sizeof(edge)); for(i=0;i<n;i++) { scanf("%d%d%d",&u,&v,&w); edge[u][v].c+=w; } ford(); printf("%d\n",f); } return 0;}
0 0
- POJ1273_Drainage Ditches(网络流)
- hdu Drainage Ditches(网络流)
- hdoj1532Drainage Ditches(网络流)
- 网络最大流--Drainage Ditches
- HDU1532 - Drainage Ditches(网络流)
- usaco 4.2 Drainage Ditches 网络流
- HDU 1532 Drainage Ditches (最大网络流)
- HDU 1532 Drainage Ditches (最大网络流)
- hdu 1532 Drainage Ditches(最大网络流)
- POJ1273 Drainage Ditches 简单网络流
- poj 1273 Drainage Ditches 网络最大流
- 网络最大流问题 poj1273 Drainage Ditches
- poj 1273 Drainage Ditches--网络流
- 【网络流】poj 1273 Drainage Ditches
- 网络流poj(1273)Drainage Ditches
- Hdu 1532 Drainage Ditches【网络流】
- PKU-1273 Drainage Ditches (网络最大流)
- POJ 1273 Drainage Ditches 【网络流】
- wamp配置
- 求和号
- js学习笔记
- java中Object转String
- 5A资源网是中国最全最大的网络资源交易与买卖平台。集合了各大网盘资源交易、游戏资源交易、软件资源交易和建站资源交易等。找优质资源首选5A资源网!
- POJ1273_Drainage Ditches(网络流)
- JAVA约瑟夫问题(丢手帕问题)
- cocos2d-x如何截屏并保存图片
- 【备忘】GPS专业词汇中英文对照
- 不懂技术的人不要对懂技术的人说这很容易实现
- SQL中char、varchar、nvarchar的区别
- 安装VisualSVN时遇到的问题-Service ‘VisualSVN Server’ failed to start
- Android开发之如何监听让服务不被杀死
- tomcat https配置