poj1459 Power Network

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Power Network
Time Limit: 2000MS Memory Limit: 32768K
Total Submissions: 23117 Accepted: 12105

Description

A power network consists of nodes (power stations, consumers and dispatchers) connected by power transport lines. A node u may be supplied with an amount s(u) >= 0 of power, may produce an amount 0 <= p(u) <= p max(u) of power, may consume an amount 0 <= c(u) <= min(s(u),c max(u)) of power, and may deliver an amount d(u)=s(u)+p(u)-c(u) of power. The following restrictions apply: c(u)=0 for any power station, p(u)=0 for any consumer, and p(u)=c(u)=0 for any dispatcher. There is at most one power transport line (u,v) from a node u to a node v in the net; it transports an amount 0 <= l(u,v) <= l max(u,v) of power delivered by u to v. Let Con=Σ uc(u)  be the power consumed in the net. The problem is to compute the maximum value of Con.

An example is in figure 1. The label x/y of power station u shows that p(u)=x and p max(u)=y. The label x/y of consumer u shows that c(u)=x and c max(u)=y. The label x/y of power transport line (u,v) shows that l(u,v)=x and l max(u,v)=y. The power consumed is Con=6. Notice that there are other possible states of the network but the value of Con cannot exceed 6.

Input

There are several data sets in the input. Each data set encodes a power network. It starts with four integers: 0 <= n <= 100 (nodes), 0 <= np <= n (power stations), 0 <= nc <= n (consumers), and 0 <= m <= n^2 (power transport lines). Follow m data triplets (u,v)z, where u and v are node identifiers (starting from 0) and 0 <= z <= 1000 is the value of l max(u,v). Follow np doublets (u)z, where u is the identifier of a power station and 0 <= z <= 10000 is the value of p max(u). The data set ends with nc doublets (u)z, where u is the identifier of a consumer and 0 <= z <= 10000 is the value of c max(u). All input numbers are integers. Except the (u,v)z triplets and the (u)z doublets, which do not contain white spaces, white spaces can occur freely in input. Input data terminate with an end of file and are correct.

Output

For each data set from the input, the program prints on the standard output the maximum amount of power that can be consumed in the corresponding network. Each result has an integral value and is printed from the beginning of a separate line.

Sample Input

2 1 1 2 (0,1)20 (1,0)10 (0)15 (1)20
7 2 3 13 (0,0)1 (0,1)2 (0,2)5 (1,0)1 (1,2)8 (2,3)1 (2,4)7
         (3,5)2 (3,6)5 (4,2)7 (4,3)5 (4,5)1 (6,0)5
         (0)5 (1)2 (3)2 (4)1 (5)4

Sample Output

15
6

Hint

The sample input contains two data sets. The first data set encodes a network with 2 nodes, power station 0 with pmax(0)=15 and consumer 1 with cmax(1)=20, and 2 power transport lines with lmax(0,1)=20 and lmax(1,0)=10. The maximum value of Con is 15. The second data set encodes the network from figure 1.

Source

 

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多源多汇点最大流,注意输出格式就行

代码如下:

/*
题目大意:有n个顶点,np个发电站,nc个用户,求最大传输电量
题目解答:典型多源多汇点的最大流问题
Source Code
*/
#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include<queue>
using namespace std;

#define maxn 110
#define inf INT_MAX
int n,np,nc,m;
int flow[maxn][maxn],cap[maxn][maxn];
int a[maxn],p[maxn];

int maxflow(int s,int t)
{
	memset(flow,0,sizeof(flow));
	int max=0;
	int u,v;
	while(1)
	{
		memset(a,0,sizeof(a));
		queue<int> q;
		q.push(s);
		a[s]=inf;
		while(!q.empty())
		{
			u=q.front();q.pop();
			for(v=0;v<=t;v++)
			{
				if(!a[v] && cap[u][v] > flow[u][v])
				{
					p[v]=u;
					a[v]=a[u] > cap[u][v] - flow[u][v] ? cap[u][v] - flow[u][v]:a[u];
					q.push(v);
				}
			}
		}
		if(!a[t]) break;
		for(u=t;u!=s;u=p[u])
		{
			flow[p[u]][u]+=a[t];
			flow[u][p[u]]-=a[t];
		}
		max+=a[t];
	}
	return max;
}
int main()
{
	//freopen("1459.txt","r",stdin);
	int i,j,k;
	int u,v;
	int cost;
	while(scanf("%d%d%d%d ",&n,&np,&nc,&m)!=EOF)
	{
		memset(cap,0,sizeof(cap));
		for(i=1;i<=m;i++)
		{
			scanf("(%d,%d)",&u,&v);//注意输入中的空格也要过滤掉
			scanf("%d ",&cap[u][v]);
			//printf("(%d,%d)",u,v);
			//printf("%d ",cap[u][v]);
		}
		for(i=1;i<=np;i++)
		{
			scanf("(%d)%d ",&u,&cost);
			//printf("(%d)%d ",u,cost);
			cap[n][u]=cost;
		}
		for(i=1;i<=nc;i++)
		{
			scanf("(%d)%d ",&u,&cost);
			//printf("(%d)%d ",u,cost);
			cap[u][n+1]=cost;
		}
		int ans=maxflow(n,n+1);//设源点S=n和汇点T=n+1;
		printf("%d\n",ans);
	}
	return 0;
}


 


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