注意计算层数的时候不是在pop之后，因为起始点不能算，所以在for里面计算

//邻接矩阵
#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
const int maxv = 1e3 + 10;
struct node {
    int v, layer;
};
int G[maxv][maxv];
bool inq[maxv];
int n, l;
int BFS(int v)
{
    int ans = 0;
    node start;
    start.v = v;
    start.layer = 0;
    queue<node>q;
    q.push(start);
    inq[start.v] = true;
    while (!q.empty())
    {
        node topNode = q.front();
        q.pop();
        int u = topNode.v;
        for (int i = 1; i <= n; i++)
        {
            node next;
            next.layer = topNode.layer + 1;
            if (G[u][i]&&inq[i]==false)
            {
                next.v = i;
                q.push(next);
                inq[i] = true;
                if (next.layer <= l)ans++;
            }
        }
    }
    return ans;
}

int main()
{
    scanf("%d%d", &n, &l);
    for (int i = 1; i <= n; i++)
    {
        int m, u;
        scanf("%d", &m);
        while (m--)
        {
            scanf("%d", &u);
            G[u][i] = 1;
        }
    }
    int k;
    scanf("%d", &k);
    while (k--)
    {
        int query;
        memset(inq, false, sizeof(inq));
        scanf("%d", &query);
        int ans=BFS(query);
        printf("%d\n", ans);
    }
    return 0;
}

邻接表写法

int BFS(int v)
{
    int ans = 0;
    queue<node>q;
    node start;
    start.v = v;
    start.layer = 0;
    q.push(start);
    inq[start.v] = true;
    while (!q.empty())
    {
        node topNode = q.front();
        q.pop();
        int u = topNode.v;
        for (int i = 0; i < Adj[u].size(); i++)
        {
            node next;
            next.v = Adj[u][i];
            next.layer = topNode.layer + 1;
            if (!inq[next.v] && next.layer <= l)
            {
                ans++;
                q.push(next);
                inq[next.v] = true;
            }
        }
    }
    return ans;
}
···