网络最大流dinic模板

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
queue<int>q;
int INF=1e9;
int n,m,head[10005],cur[10005],ct=1,s,t,d[10005],ans;
struct N{
    int to,next,w;
}edge[200005];
void add(int x,int y,int z)
{
    edge[++ct]=(N){y,head[x],z};head[x]=ct;
    edge[++ct]=(N){x,head[y],0};head[y]=ct;
}
bool bfs()
{
    memset(d,0,sizeof d);
    while(q.size())q.pop();
    d[s]=1;
    q.push(s);
    while(q.size())
    {
        int x=q.front();q.pop();
        for(int i=head[x];i;i=edge[i].next)
        {
            int u=edge[i].to;
            if(!d[u]&&edge[i].w)//残量网络 
            {
                d[u]=d[x]+1;
                q.push(u);
            }
        }
    }
    return d[t];
}
int dfs(int x,int f)
{
    if(x==t)return f;//
    int res=0,tmp=0;
    for(int i=cur[x];i;i=edge[i].next)
    {
        int u=edge[i].to;
        if(d[u]==d[x]+1&&edge[i].w)
        {
            tmp=dfs(u,min(edge[i].w,f-res));
            edge[i].w-=tmp;
            edge[i^1].w+=tmp;
            res+=tmp;
            if(edge[i].w)cur[x]=i;
            if(res==f)return f;//
        }
    }
    if(!res)d[x]=0;//剪枝 
    return res;
}
int main()
{
    scanf("%d%d",&n,&m);
    scanf("%d%d",&s,&t);
    int x,y,z;
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d%d",&x,&y,&z);
        add(x,y,z);
    }
    while(bfs())
    {
        for(int i=1;i<=n;i++)cur[i]=head[i];
        ans+=dfs(s,INF);
    }
    printf("%d",ans);
    return 0;
}