hdu 1532 Drainage Ditches（网络流dinic模板）

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网络流dinic模板
刘汝佳版
代码：
#include <iostream>#include <cstdio>#include <cstring>#include <vector>#include <queue>#define inf 10000000#define maxn 1000using namespace std;struct edge{    int from,to,cap,flow;    edge(){}    edge(int from,int to,int cap,int flow):from(from),to(to),cap(cap),flow(flow){}};struct dinic{    int n,m,s,t;    vector<edge> edges;    vector<int > G[maxn];    bool vis[maxn];    int cur[maxn];    int d[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 <int> Q;        Q.push(s);        d[s]=0;        vis[s]=1;        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]=1;                    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[e.to]==d[x]+1)&&(f=dfs(e.to,min(e.cap-e.flow,a)))>0){                e.flow+=f;                edges[G[x][i]^1].flow-=f;                flow+=f;                a-=f;                if(a==0) break;            }        }        return flow;    }    int maxflow(int a,int b){        s=a;t=b;        int flow=0;        while(bfs()){            memset(cur,0,sizeof(cur));            flow+=dfs(s,inf);        }        return flow;    }};int main(){    int m,n;    while(~scanf("%d%d",&m,&n)){        dinic D;        for(int i=1;i<=m;i++){            int s,t,d;            scanf("%d%d%d",&s,&t,&d);            D.addedge(s,t,d);        }        int res=D.maxflow(1,n);        printf("%d\n",res);    }    return 0;}
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