網路流Dinic演算法

標籤：bre   eof   pre   演算法   code   empty   for   while   ems   

詳細待..

紫書模板

 

const int maxn = 1e5+200;const int  inf = 0x3f3f3f3f;struct Edge {    int from, to, cap, flow;    Edge (int u, int v, int c, int f) : from(u), to(v), cap(c), flow(f) { }};struct Dinic {    int n, m, s, t;    vector<Edge> edges;    vector<int> G[maxn];    bool vis[maxn];    int d[maxn];    int cur[maxn];        void init(int n) {        for (int i=0; i<n; ++i) G[i].clear();        edges.clear();    }        void add(int u, int v , int val) {        edges.push_back(Edge(u, v, val, 0));        edges.push_back(Edge(u, v, 0, 0));        m = edges.size();        G[u].push_back(m-2);        G[v].push_back(m-1);    }        bool BFS() {        memset(vis, 0, sizeof(vis));        queue<int> 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, 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;    }}Dic;

 

網路流Dinic演算法