PAT 1090 危险品装箱 （25 分）

#include <iostream>
#include <vector>
#include <map>
using namespace std;
int main() {
    int n, k, t1, t2;
    map<int,vector<int>> m;
    scanf("%d%d", &n, &k);
    for (int i = 0; i < n; i++) {
        scanf("%d%d", &t1, &t2);
        m[t1].push_back(t2);
        m[t2].push_back(t1);
    }
    while (k--) {
        int cnt, flag = 0, a[100000] = {0};
        scanf("%d", &cnt);
        vector<int> v(cnt);
        for (int i = 0; i < cnt; i++) {
            scanf("%d", &v[i]);
            a[v[i]] = 1;
        }
        for (int i = 0; i < v.size(); i++)
            for (int j = 0; j < m[v[i]].size(); j++)
                if (a[m[v[i]][j]] == 1) flag = 1;
        printf("%s\n",flag ? "No" :"Yes");
    }
    return 0;
}