网络流24题-运输问题（费用流）

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 const int inf=0x3f3f3f3f;
  4 const int MAXN=10000;//点的总数
  5 const int MAXM=100000;//边的总数
  6 struct Edge{
  7     int to,nxt,cap,flow,cost;
  8 }edge[MAXM];
  9 int head[MAXN],tot;
 10 int pre[MAXN],dis[MAXN];
 11 bool vis[MAXN];
 12 int N;//节点总个数，节点编号0~N-1
 13 void init()
 14 {
 15     tot=0;
 16     memset(head,-1,sizeof(head));
 17 }
 18 void addedge(int u,int v,int cap,int cost)
 19 {
 20     edge[tot].to=v;     edge[tot].cap=cap;   edge[tot].cost=cost;
 21     edge[tot].flow=0;   edge[tot].nxt=head[u];  head[u]=tot++;
 22 
 23     edge[tot].to=u;     edge[tot].cap=0;    edge[tot].cost=-cost;
 24     edge[tot].flow=0;    edge[tot].nxt=head[v];     head[v]=tot++;
 25 }
 26 bool spfa(int s,int t)
 27 {
 28     queue<int>q;
 29     for(int i=0;i<N;i++)
 30     {
 31         dis[i]=inf;
 32         vis[i]=false;
 33         pre[i]=-1;
 34     }
 35     dis[s]=0;
 36     vis[s]=true;
 37     q.push(s);
 38     while(!q.empty())
 39     {
 40         int u=q.front();    q.pop();
 41         vis[u]=false;
 42         for(int i=head[u];i!=-1;i=edge[i].nxt)
 43         {
 44             int v=edge[i].to;
 45             if(edge[i].cap>edge[i].flow&&dis[v]>dis[u]+edge[i].cost)
 46             {
 47                 dis[v]=dis[u]+edge[i].cost;
 48                 pre[v]=i;
 49                 if(!vis[v])
 50                 {
 51                     vis[v]=true;
 52                     q.push(v);
 53                 }
 54             }
 55         }
 56     }
 57     if(pre[t]==-1)  return false;
 58     else            return true;
 59 }
 60 int MCMF(int s,int t,int &cost)
 61 {
 62     int flow=0;
 63     cost=0;
 64     while(spfa(s,t))
 65     {
 66         int minn=inf;
 67         for(int i=pre[t];i!=-1;i=pre[edge[i^1].to])
 68         {
 69             if(minn>edge[i].cap-edge[i].flow)
 70                 minn=edge[i].cap-edge[i].flow;
 71         }
 72         for(int i=pre[t];i!=-1;i=pre[edge[i^1].to])
 73         {
 74             edge[i].flow+=minn;
 75             edge[i^1].flow-=minn;
 76             cost+=edge[i].cost*minn;
 77         }
 78         flow+=minn;
 79     }
 80     return flow;
 81 }
 82 int c[200][200],a[200],b[200];
 83 int main()
 84 {
 85     ios::sync_with_stdio(false);
 86     cin.tie(0);cout.tie(0);
 87     int n,m;
 88     cin>>n>>m;
 89     int s=0,t=n+m+1;
 90     N=t+1;
 91     init();
 92     for(int i=1;i<=n;i++)
 93     {
 94         cin>>a[i];
 95         addedge(s,i,a[i],0);
 96     }
 97     for(int i=1;i<=m;i++)
 98     {
 99         cin>>b[i];
100         addedge(i+n,t,b[i],0);
101     }
102     for(int i=1;i<=n;i++)
103     {
104         for(int j=1;j<=m;j++)
105         {
106             cin>>c[i][j];
107             addedge(i,j+n,inf,c[i][j]);
108         }
109     }
110     int cost=0;
111     MCMF(s,t,cost);
112     cout<<cost<<endl;
113     init();
114     for(int i=1;i<=n;i++)   addedge(s,i,a[i],0);
115     for(int i=1;i<=m;i++)   addedge(i+n,t,b[i],0);
116     for(int i=1;i<=n;i++)
117     {
118         for(int j=1;j<=m;j++)
119         {
120             addedge(i,j+n,inf,-c[i][j]);
121         }
122     }
123     cost=0;
124     MCMF(s,t,cost);
125     cout<<-cost<<endl;
126     return 0;
127 }