Dinic - 模板

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

struct Dinic {
    int n, m, s, t;
    vector edges;
    vector G[maxn];
    bool vis[maxn];
    int d[maxn];
    int cur[maxn];
	
    void addedge(int from, int to, int cap) {
        edges.push_back((Edge){ from, to, cap, 0 });
        edges.push_back((Edge){ to, from, 0, 0 });
        m = edges.size();
        G[from].push_back(m - 2);
        G[to].push_back(m - 1);
    }
	
    bool BFS() {
        memset(vis, 0, sizeof(vis));
        queue Q;
        Q.push(s);
        d[s] = 0;
        vis[s] = true;
        while(!Q.empty()) {
            int x = Q.front();
            Q.pop();
            for (int i = 0; i < G[x].size(); i++) {
                Edge &e = edges[G[x][i]];
                if (!vis[e.to] && e.cap > e.flow) {
                    vis[e.to] = true;
                    d[e.to] = d[x] + 1;
                    Q.push(e.to);
                }
            }
        }
        return vis[t];
    }
	
    int DFS(int x, int a) {
        if (x == t || a == 0) return a;
        int flow = 0;
        int f;
        for (int &i = cur[x]; i < G[x].size(); i++) {
            Edge &e = edges[G[x][i]];
            if (d[x] + 1 == d[e.to] && (f = DFS(e.to, min(a, e.cap - e.flow))) > 0) {
                e.flow += f;
                edges[G[x][i] ^ 1].flow -= f;
                flow += f;
                a -= f;
                if (a == 0) break;
            }
        }
        return flow;  
    }
	
    int maxflow(int s, int t) {
        this->s = s;
        this->t = t;
        int flow = 0;
        while (BFS()) {
            memset(cur, 0, sizeof(cur));
            flow += DFS(s, inf);
        }
        return flow; 
    } 
};