求助qwq

#include<cstdio>
#include<iostream>
#include<queue>
#include<cstring>
using namespace std;
const int maxN=1e6 + 100,inf=1e9;
struct Node
{
    int to,value,next;
    Node() {}
    Node(int to,int value,int next) : to(to),value(value),next(next) {}
}edge[maxN*2+1];
int tot=1,head[maxN+1],n,m;
int s,t,dep[maxN+1],ans=0;
int to[maxN+1];
bool flag[maxN+1];
int read()
{
    int num=0,f=1;
    char ch=getchar();
    while(!isdigit(ch)) {if(ch=='-') f=-1; ch=getchar();}
    while(isdigit(ch)) num=(num<<3)+(num<<1)+(ch^48),ch=getchar();
    return num*f;
}
void add(int x,int y,int t)
{
    edge[++tot]=Node(y,t,head[x]); head[x]=tot;
    edge[++tot]=Node(x,0,head[y]); head[y]=tot;
}
bool bfs()
{
    memset(dep,0,sizeof(dep));
    queue<int> q;
    dep[s]=1; q.push(s);
    while(!q.empty())
    {
        int x=q.front(); q.pop();
        for(int i=head[x];i;i=edge[i].next)
           if(!dep[edge[i].to]&&edge[i].value)
           {
               dep[edge[i].to]=dep[x]+1;
               q.push(edge[i].to);
           }
    }
    return dep[t]>0;
}
int dfs(int x,int num)
{
    if(x==t) return num;
    int sum=0;
    for(int i=head[x];i;i=edge[i].next)
       if(dep[edge[i].to]==dep[x]+1&&edge[i].value)
       {
           int tmp=dfs(edge[i].to,min(edge[i].value,num));
           if(tmp) to[x]=edge[i].to,flag[edge[i].to-n]=(x!=s);
           num-=tmp; sum+=tmp;
           edge[i].value-=tmp; edge[i^1].value+=tmp;
           if(!num) break;
       }
    return sum;
}
int main()
{
    n=read(),m=read();
    s=0,t=2*n+1;
    for(int i=1;i<=n;i++) add(s,i,1),add(i+n,t,1);
    for(int i=1;i<=m;i++)
    {
        int x=read(),y=read();
        add(x,y+n,1);
    }
    while(bfs()) ans+=dfs(s,inf);
    for(int i=1;i<=n;i++)
       if(!flag[i])
       {
           int now=i;
           printf("%d ",now);
           while(to[now]!=t&&to[now]) printf("%d ",to[now]-n),now=to[now]-n;
           printf("\n");
       }
    printf("%d",n-ans);
    return 0;
}