最大流模板2

template<int N,typename T> struct MaxFlow {    int s,t,head[N],etot,que[N],qf,qe,dis[N],cur[N];    struct Edge {int v,next; T cap;}g[501000];    void init() {        memset(head,-1,sizeof(head)); etot = 0;    }    void add_edge(int u,int v,T cap) {        g[etot].v = v; g[etot].next = head[u]; g[etot].cap = cap; head[u] = etot ++;        g[etot].v = u; g[etot].next = head[v]; g[etot].cap = 0; head[v] = etot ++;    }    bool bfs() {        memset(dis,-1,sizeof(dis));        memcpy(cur,head,sizeof(cur));        dis[t] = N;        qf = qe = 0;        que[qe++] = t;        while (qf!=qe) {            int u = que[qf++];            for (int i = head[u]; i != -1; i = g[i].next) {                Edge &e = g[i];                if (g[i^1].cap && dis[e.v] == -1) {                    dis[e.v] = dis[u] - 1;                    que[qe++] = e.v;                }            }        }        return dis[s] != -1;    }    T dfs(int u,T a) {        if (u==t) return a;        T flow = 0,f;        for (int &i = cur[u]; i != -1; i = g[i].next) {            Edge &e = g[i];            if (e.cap && dis[e.v] > dis[u]) {                f = dfs(e.v,std::min(a,e.cap));                flow += f;                e.cap -= f;                g[i^1].cap += f;                a -= f;                if (a==0) break;            }        }        if (flow==0) dis[u] = -1;        return flow;    }    T dinic(int _s,int _t) {        s = _s; t = _t;        T flow = 0;        while (bfs()) flow += dfs(s,(T)1e30);        return flow;    }};