教輔的組成

類型：最大流

類似于二分圖比對，但是對于書要拆點，否則會多次用。

#include <cstdio>
#include <iostream>
#include <queue>
#include <cstring> 
#define il inline
using namespace std;
const int inf=;
const int maxm=;
int head[maxm],to[maxm*],cap[maxm*],net[maxm*],deep[maxm],cnt=;
il void add(int x,int y,int c){cnt++,to[cnt]=y,cap[cnt]=c,net[cnt]=head[x],head[x]=cnt;}
queue <int> dl;
il bool BFS(int s,int t)
{
    while(!dl.empty()) dl.pop();
    memset(deep,-,sizeof(deep));
    dl.push(s),deep[s]=;
    while(!dl.empty())
    {
        int x=dl.front();dl.pop();
        for(int i=head[x];i;i=net[i])
         if(cap[i]>&&deep[to[i]]==-)
          dl.push(to[i]),deep[to[i]]=deep[x]+;
    }
    return deep[t]==-?:;
}
int dfs(int now,int flow,int t)
{
    if(now==t) return flow;
    int w,used=;
    for(int i=head[now];i;i=net[i])
    {
        int v=to[i];
        if(deep[v]==deep[now]+&&cap[i])
        {
            w=dfs(v,min(flow-used,cap[i]),t);
            cap[i]-=w;
            cap[i^]+=w;
            used+=w;
            if(used==flow) return flow;
        }
    }
    if(!used) deep[now]=-;
    return used;
}
il int dinic(int s,int t)
{
    int maxflow=;
    while(BFS(s,t)) maxflow+=dfs(s,inf,t);
    return maxflow;
}
inline void adx(int x,int y,int cax)
{
    add(x,y,cax),add(y,x,);
}
il int read()
{
    int x=,w=;
    char ch=;
    while(ch<'0'||ch>'9') 
    {
        if(ch=='-') w=-;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
     x=(x<<)+(x<<)+ch-'0',ch=getchar();
    return x*w;
}
int main()
{
    //freopen("text.in","r",stdin);
    int n1,n2,n3;
    int s=,t=;
    scanf("%d%d%d",&n1,&n2,&n3);
    int n=n1+n2+n3+; 
    int m=read();
    for(int i=;i<=n1;i++)
     adx(i,i+n,);
    for(int i=;i<=n2;i++)
     adx(s,i+n1,);
    for(int i=;i<=n3;i++)
     adx(i+n1+n2,t,);
    for(int i=;i<=m;i++)
    {
        int u=read(),v=read();
        adx(v+n1,u,);
    }
    m=read();
    for(int i=;i<=m;i++)
    {
        int u=read(),v=read();
        adx(u+n,v+n1+n2,);
    }

    printf("%d\n",dinic(s,t));
    return ;
}