BellmanFord（费用流） - 模板

struct Edge {
    int from, to, cap, flow, cost;
};

struct MCMF {
    int n, m, s, t;
    vector edges;
    vector G[maxn];
    int inq[maxn];
    int d[maxn];
    int p[maxn];
    int a[maxn];
	
    void init(int n) {
        this->n = n;
        for (int i = 0; i < n; i++) G[i].clear();
        edges.clear();
    }
	
    void addedge(int from, int to, int cap, int cost) {
        edges.push_back((Edge){ from, to, cap, 0, cost });
        edges.push_back((Edge){ to, from, 0, 0, -cost });
        m = edges.size();
        G[from].push_back(m - 2);
        G[to].push_back(m - 1);
    }
	
    bool BellmanFord(int s, int t, int &flow, int &cost) {
        for (int i = 0; i < n; i++) d[i] = inf;
        memset(inq, 0, sizeof(inq));
        d[s] = 0;
        inq[s] = 1;
        p[s] = 0;
        a[s] = inf;		
        queue Q;
        Q.push(s);
        while (!Q.empty()) {
            int u = Q.front();
            Q.pop();
            inq[u] = 0;
            for (int i = 0; i < G[u].size(); i++) {
                Edge &e = edges[G[u][i]];
                if (e.cap > e.flow && d[e.to] > d[u] + e.cost) {
                    d[e.to] = d[u] + e.cost;
                    p[e.to] = G[u][i];
                    a[e.to] = min(a[u], e.cap - e.flow);
                    if (!inq[e.to]) {
                        Q.push(e.to);
                        inq[e.to] = 1;
                    }
                }
            }
        }
        if (d[t] == inf) return false;
        flow += a[t];
        cost += d[t] * a[t];
        int u = t;
        while (u != s) {
            edges[p[u]].flow += a[t];
            edges[p[u] ^ 1].flow -= a[t];
            u = edges[p[u]].from;
        }
        return true;
    }
	
    int mincost(int s, int t) {
        int flow = 0;
        int cost = 0;
        while (BellmanFord(s, t, flow, cost));
        return cost;
    }
};