luogu1231 教辅的组成

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;
int nb, nc, na, hea[40005], cnt, cur[40005], ss, tt, uu, vv, ww, maxFlow;
int lev[40005];
const int oo=0x3f3f3f3f;
queue<int> d;
struct Edge{
    int too, nxt, val;
}edge[150005];
void add_edge(int fro, int too, int val){
    edge[cnt].nxt = hea[fro];
    edge[cnt].too = too;
    edge[cnt].val = val;
    hea[fro] = cnt++;
}
void addEdge(int fro, int too, int val){
    add_edge(fro, too, val);
    add_edge(too, fro, 0);
}
bool bfs(){
    memset(lev, 0, sizeof(lev));
    lev[ss] = 1;
    d.push(ss);
    while(!d.empty()){
        int x=d.front();
        d.pop();
        for(int i=hea[x]; i!=-1; i=edge[i].nxt){
            int t=edge[i].too;
            if(!lev[t] && edge[i].val>0){
                lev[t] = lev[x] + 1;
                d.push(t);
            }
        }
    }
    return lev[tt]!=0;
}
int dfs(int x, int lim){
    if(x==tt)   return lim;
    int addFlow=0;
    for(int &i=cur[x]; i!=-1 && addFlow<lim; i=edge[i].nxt){
        int t=edge[i].too;
        if(lev[t]==lev[x]+1 && edge[i].val>0){
            int tmp=dfs(t, min(lim-addFlow, edge[i].val));
            edge[i].val -= tmp;
            edge[i^1].val += tmp;
            addFlow += tmp;
        }
    }
    return addFlow;
}
void dinic(){
    while(bfs()){
        for(int i=0; i<=tt; i++)    cur[i] = hea[i];
        maxFlow += dfs(ss, oo);
    }
}
int main(){
    memset(hea, -1, sizeof(hea));
    cin>>nb>>nc>>na;
    ss = 0; tt = nb + nb + nc + na + 1;
    cin>>ww;
    while(ww--){
        scanf("%d %d", &uu, &vv);
        addEdge(vv, uu+nc, 1);
    }
    cin>>ww;
    while(ww--){
        scanf("%d %d", &uu, &vv);
        addEdge(uu+nc+nb, vv+nb+nc+nb, 1);
    }
    for(int i=1; i<=nc; i++)
        addEdge(ss, i, 1);
    for(int i=nc+1; i<=nc+nb; i++)
        addEdge(i, i+nb, 1);
    for(int i=nb+nc+nb+1; i<=nb+nc+na+nb; i++)
        addEdge(i, tt, 1);
    dinic();
    cout<<maxFlow<<endl;
    return 0;
}