最小费用最大流模板

const int MAXN = 1010;const int MAXM = 504000;struct Edge{    int to,next,cap,flow,cost;}edge[MAXM];int head[MAXM],tol;int pre[MAXN],dis[MAXN];bool vis[MAXN];int N;void Init(int n){    N = n;    tol = 0;    memset(head,-1,sizeof(head));}void addedge(int u,int v,int cap,int cost){    edge[tol].to = v;    edge[tol].cap = cap;    edge[tol].cost = cost;    edge[tol].flow = 0;    edge[tol].next = head[u];    head[u] = tol++;    edge[tol].to = u;    edge[tol].cap = 0;    edge[tol].cost = -cost;    edge[tol].flow = 0;    edge[tol].next = head[v];    head[v] = tol++;}bool spfa(int s,int t){    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() == false)    {        int u = q.front();        q.pop();        vis[u] = false;        for(int i = head[u];i != -1;i = edge[i].next)        {            int v = edge[i].to;            if(edge[i].cap > edge[i].flow && dis[v] > dis[u] + edge[i].cost)            {                dis[v] = dis[u] + edge[i].cost;                pre[v] = i;                if(vis[v] == false)                {                    vis[v] = true;                    q.push(v);                }            }        }    }    if(pre[t] == -1)        return false;    return true;}int MCMF(int s,int t,int &cost){    int flow = 0;    cost = 0;    while(spfa(s,t))    {        int Min = INF;        for(int i = pre[t];i != -1;i = pre[edge[i^1].to])            Min = min(Min,edge[i].cap - edge[i].flow);        for(int i = pre[t];i != -1;i = pre[edge[i^1].to])        {            edge[i].flow += Min;            edge[i^1].flow -= Min;            cost += edge[i].cost*Min;        }        flow += Min;    }    return flow;}