白书上的Dinic模板

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

using namespace std;

const int maxn=1111;
const int maxm=1111111;
const int INF=1e9;

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

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,int s,int t){
        this->n=n;
        this->s=s;
        this->t=t;
        for (int i=0;i<n;i++) G[i].clear();
        edges.clear();
        m=0;
    }

    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<int>que;
        que.push(s);
        d[s]=0;
        vis[s]=true;
        while (!que.empty()){
            int x=que.front();que.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;
                    que.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;
    }

}solver;