poj1459网络流之多源点最大流

这题想了好久，一直认为应该bfs更新后求最小值把发电站最大发电加进去，但是又发现这样求增广路的时候会导致用户更新出错，

加源点和汇点也考虑到了，没想到居然发电量就是超级源到源点的v，居然这么简单@。@

#include<map>

#include<set>

#include<cmath>

#include<queue>

#include<stack>

#include<vector>

#include<cstdio>

#include<cassert>

#include<iomanip>

#include<cstdlib>

#include<cstring>

#include<iostream>

#include<algorithm>

#define pi acos(-1)

#define ll long long

#define mod 1000000007

#define ls l,m,rt<<1

#define rs m+1,r,rt<<1|1

#pragma comment(linker, "/STACK:1024000000,1024000000")

using namespace std;

const double g=10.0,eps=1e-;

const int N=+,maxn=,inf=;

int v[N][N],s,t,n;

int pre[N];

bool vis[N];

bool bfs()

{

    memset(vis,,sizeof vis);

    memset(pre,,sizeof pre);

    vis[s]=;

    queue<int>q;

    q.push(s);

    while(!q.empty()){

        int x=q.front();

        if(x==t)return ;

        q.pop();

        for(int i=;i<=n+;i++)

        {

            if(!vis[i]&&v[x][i])

            {

                vis[i]=;

                q.push(i);

                pre[i]=x;

            }

        }

    }

    return ;

}

int max_flow()

{

    int ans=;

    while(){

        if(!bfs())return ans;

        int minn=inf+;

        for(int i=t;i!=s;i=pre[i])

            minn=min(minn,v[pre[i]][i]);

        for(int i=t;i!=s;i=pre[i])

        {

            v[pre[i]][i]-=minn;

            v[i][pre[i]]+=minn;

        }

        ans+=minn;

    }

}

int main()

{

    ios::sync_with_stdio(false);

    cin.tie();

    int np,nc,m;

    while(cin>>n>>np>>nc>>m){

        memset(v,,sizeof v);

        int a,b,c;

        char ru;

        while(m--){

            cin>>ru;

            cin>>a;

            cin>>ru;

            cin>>b;

            cin>>ru;

            cin>>c;

            v[a][b]+=c;

        }

        while(np--){

            cin>>ru;

            cin>>a;

            cin>>ru;

            cin>>b;

            v[n][a]=b;

        }

        while(nc--){

            cin>>ru;

            cin>>a;

            cin>>ru;

            cin>>b;

            v[a][n+]=b;

        }

        s=n,t=n+;

        cout<<max_flow()<<endl;

    }

    return ;

}