hdu3879 最大权闭合回路

题意: 有n个基站可以建立，然后m个团体会使用这些基站进行工作，地i个团体会适应Ai Bi 这两个基站， 如果建成收益Ci,  第j个基站花费Pj，求如何建立使得收益最大，

将每个团体看以一个点，然后从这个点出发向那两个点建一条边，他自己想s建立一个为Ci的边，第j个基站想t建立一个容量为Pj的边，跑一遍最小割，然后所有正权减去这个最小割得到答案

#include <iostream>
#include <algorithm>
#include <string.h>
#include <cstdio>
#include <vector>
#include <queue>
using namespace std;
const int maxn=;
const int INF=;
struct Dinic
{

    struct Edge{
      int from,to,cap,flow;
      Edge(int cfrom=,int cto=,int ccap=,int cflow=)
      {
          from=cfrom;  to=cto; cap=ccap; flow=cflow;
      }
    };
    int n,m,s,t;
    vector<Edge>edges;
    vector<int>G[maxn];
    bool vis[maxn];
    int d[maxn];
    int cur[maxn];
    void init(int n)
    {
        m=;
        for(int i=; i<=n; i++)G[i].clear();
        edges.clear();
    }
    void addEdge(int from,int to, int cap)
    {
        edges.push_back(Edge(from,to,cap,) );
        edges.push_back(Edge(to,from,,));
        m+=;
        G[from].push_back(m-);
        G[to].push_back(m-);
    }
    bool BFS()
    {
        memset(vis,,sizeof(vis));
        queue<int>Q;
       Q.push(s);
      d[s]=;
      vis[s]=;
      while(!Q.empty())
        {
            int x=Q.front(); Q.pop();
            for(int i=; i<G[x].size(); i++)
            {
                Edge &e = edges[G[x][i]];
                if(vis[e.to]==false&&e.cap>e.flow)
                {
                     vis[e.to]=;
                     d[e.to]=d[x]+;
                     Q.push(e.to);
                }
            }
        }
        return vis[t];
    }
    int DFS(int x,int a)
    {
        if(x==t||a==)return a;
        int flow=,f;
        for(int &i=cur[x]; i<G[x].size(); i++)
        {
            Edge &e=edges[G[x][i]];
            if(d[x]+==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>)
            {
                e.flow+=f;
                edges[G[x][i]^].flow-=f;
                flow+=f;
                a-=f;
                if(a==)break;
            }
        }
        return flow;
    }
    int Maxflow(int s,int t)
    {
        this->s=s;this->t=t;
        int flow=;
        while(BFS())
        {
            memset(cur,,sizeof(cur));
            flow+=DFS(s,INF);
        }
        return flow;
    }
}T;
int P[maxn];
int A[maxn],B[maxn],X[maxn];
int main()
{
     int n,m;
     while(scanf("%d%d",&n,&m)==)
     {
         int S=;
         T.init(n+m+);
         int ss=n+m+,tt=n+m+;
         for(int i=; i<=n; i++)
         {
             scanf("%d",&P[i]);
             S+=P[i];
             T.addEdge(i,tt,P[i]);
         }
         int S1=;
         for(int i=; i<=m; i++)
            {

                 scanf("%d%d%d",&A[i],&B[i],&X[i]);
                 T.addEdge(ss,n+i,X[i]);
                 S+=X[i];
                 S1+=X[i];
            }
         for(int j=; j<=m; j++)
         {
                T.addEdge(n+j,A[j],S);
                T.addEdge(n+j,B[j],S);
         }
         int ans=T.Maxflow(ss,tt);
         printf("%d\n",S1-ans);
     }
     return ;
}

ISAP

#include <iostream>
#include <algorithm>
#include <string.h>
#include <cstdio>
#include <vector>
#include <queue>
using namespace std;
const int maxn=;
const int INF=;
struct ISAP
{

    struct Edge{
      int from,to,cap,flow;
      Edge(int cfrom=,int cto=,int ccap=,int cflow=)
      {
          from=cfrom;  to=cto; cap=ccap; flow=cflow;
      }
    };
    int n,m,s,t;
    vector<Edge>edges;
    vector<int>G[maxn];
    bool vis[maxn];
    int d[maxn];
    int cur[maxn];
    int p[maxn];
    int num[maxn];
    void init(int n)
    {
        m=;
        this->n=n;
        for(int i=; i<=n; i++)G[i].clear();
        edges.clear();
    }
    void addEdge(int from,int to, int cap)
    {
        edges.push_back(Edge(from,to,cap,) );
        edges.push_back(Edge(to,from,,));
        m+=;
        G[from].push_back(m-);
        G[to].push_back(m-);
    }
    void BFS()
    {
        memset(vis,,sizeof(vis));
        queue<int>Q;
       Q.push(t);
      d[t]=;
      vis[t]=;
      while(!Q.empty())
        {
            int x=Q.front(); Q.pop();
            for(int i=; i<G[x].size(); i++)
            {
                Edge &e = edges[G[x][i]];
                if(vis[e.to]==false)
                {
                     vis[e.to]=;
                     d[e.to]=d[x]+;
                     Q.push(e.to);
                }
            }
        }
    }
    int Augment()
    {
        int x=t,a=INF;
        while(x!=s)
        {
            Edge &e=edges[p[x]];
            a=min(a,e.cap-e.flow);
            x=edges[p[x]].from;
        }
        x=t;
        while(x!=s)
        {
            edges[p[x]].flow+=a;
            edges[p[x]^].flow-=a;
            x=edges[p[x]].from;
        }
        return a;
    }
    int Maxflow(int s,int t)
    {
        this->s=s;this->t=t;
        int flow=;
        BFS();
        memset(num,,sizeof(num));
        for(int i=; i<=n; i++)num[d[i]]++;
        int x=s;
        memset(cur,,sizeof(cur));
        while(d[s]<n)
        {
            if(x==t)
            {
                flow+=Augment();
                x=s;
            }
            int ok=;
            for(int i=cur[x]; i<G[x].size(); i++)
            {
                Edge &e=edges[G[x][i]];
                if(e.cap>e.flow&&d[x]==d[e.to]+)
                {
                    ok=;
                    p[e.to]=G[x][i];
                    cur[x]=i;
                    x=e.to;
                    break;
                }
            }
            if(ok==)
            {
                int m=n-;
                for(int i=; i<G[x].size(); i++)
                {
                    Edge &e=edges[G[x][i]];
                    if(e.cap>e.flow)m=min(m,d[e.to]);
                }
                if(--num[d[x]]==)break;
                num[d[x]=m+]++;
                cur[x]=;
                if(x!=s)x=edges[p[x]].from;
            }
        }
        return flow;
    }
}T;
int P[maxn];
int A[maxn],B[maxn],X[maxn];
int main()
{
     int n,m;
     while(scanf("%d%d",&n,&m)==)
     {
         int S=;
         T.init(n+m+);
         int ss=n+m+,tt=n+m+;
         for(int i=; i<=n; i++)
         {
             scanf("%d",&P[i]);
             S+=P[i];
             T.addEdge(i,tt,P[i]);
         }
         int S1=;
         for(int i=; i<=m; i++)
            {

                 scanf("%d%d%d",&A[i],&B[i],&X[i]);
                 T.addEdge(ss,n+i,X[i]);
                 S+=X[i];
                 S1+=X[i];
            }
         for(int j=; j<=m; j++)
         {
                T.addEdge(n+j,A[j],S);
                T.addEdge(n+j,B[j],S);
         }
         int ans=T.Maxflow(ss,tt);
         printf("%d\n",S1-ans);
     }
     return ;
}