最小费用最大流模板

int tol,head[maxn];
struct edge
{
    int to,next,cap,flow,cost;
}es[maxm];
void addedge( int u , int v , int cap , int cost )
{
    es[tol].to = v;
    es[tol].cap = cap;
    es[tol].cost = cost;
    es[tol].flow = 0;
    es[tol].next = head[u];
    head[u] = tol++;
    es[tol].to = u;
    es[tol].cap = 0;
    es[tol].cost = -cost;
    es[tol].flow = 0;
    es[tol].next = head[v];
    head[v] = tol++;
}
int pre[maxn],dis[maxn]; bool vis[maxn];
bool spfa( int s , int t , int n )
{
    queue<int>Q;
    for ( int i=0 ; i<n ; i++ )
    {
        dis[i] = inf;
        vis[i] = false;
        pre[i] = -1;
    }
    dis[s] = 0;
    vis[s] = true;
    Q.push(s);
    while( !Q.empty() )
    {
        int u = Q.front(); Q.pop(); vis[u] = false;
        for ( int i=head[u] ; i!=-1 ; i=es[i].next )
        {
            int v = es[i].to;
            if ( es[i].cap>es[i].flow&&dis[v]>dis[u]+es[i].cost )
            {
                dis[v] = dis[u]+es[i].cost;
                pre[v] = i;
                if ( !vis[v] )
                {
                    vis[v] = true;
                    Q.push(v);
                }
            }
        }
    }
    if ( pre[t]==-1 ) return false;
    else return true;
}
void MCMF( int s , int t , int n )
{
    int flow = 0;
    int cost = 0;
    while ( spfa( s , t , n ) )
    {
        int minx = inf;
        for ( int i=pre[t] ; i!=-1 ; i=pre[es[i^1].to] )
        {
            if ( minx>es[i].cap-es[i].flow )
                minx = es[i].cap-es[i].flow;
        }
        for ( int i=pre[t] ; i!=-1 ; i=pre[es[i^1].to] )
        {
            es[i].flow += minx;
            es[i^1].flow -= minx;
            cost += es[i].cost*minx;
        }
        flow += minx;
    }
    printf ( "%d\n" , cost );
}