@[x17875487211](/user/490694) 你的感觉是正确的，我也在这个地方错了inf次。我的解决办法是先出队虚点，再出队实点，这样保证在队内的都是实点：
```cpp
#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll vis[3005],in[3005];
vector<ll> to[3005];
int main() {
ll n,m;
cin >> n >> m;
for (ll i=1; i<=m; i++) {
ll s;
cin >> s;
ll st,ed;
cin >> st;
memset(vis,0,sizeof(vis));
for (ll j=2; j<s; j++) {
ll x;
cin >> x;
vis[x]=1;
}
cin >> ed;
vis[st]=1,vis[ed]=1;
for (ll j=st; j<=ed; j++) {
if (vis[j]) {
in[j]++;
to[i+n].push_back(j);
}
}
for (ll j=st; j<=ed; j++) {
if (!vis[j]) {
in[i+n]++;
to[j].push_back(i+n);
}
}
}
ll cnt=0;
queue<ll> q;
for (ll i=1; i<=m; i++) {
if (in[i+n]==0) {
in[i+n]--;
for (ll j:to[i+n]) {
in[j]--;
}
}
}
for (ll i=1; i<=n; i++) {
if (in[i]==0)q.push(i),in[i]--;
}
while (!q.empty()) {
while (!q.empty()) {
ll tp=q.front();
// cout << tp << endl;
q.pop();
for (ll i:to[tp]) {
in[i]--;
}
}
cnt++;
for (ll i=1; i<=m; i++) {
if (in[i+n]==0) {
in[i+n]--;
for (ll j:to[i+n]) {
in[j]--;
}
}
}
for (ll i=1; i<=n; i++) {
if (in[i]==0) {
q.push(i),in[i]--;
}
}
}
cout << cnt;
return 0;
}
```
by piggy123 @ 2022-03-16 10:07:25
请问有没有具体的例子，什么情况虚点和实点在同一层
by x17875487211 @ 2022-03-16 13:27:10