L2005 集合相似度

#include <bits/stdc++.h>

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<vector<int>> v;
    for (int i = 0; i < n; i++) {
        int m; cin >> m;
        vector<int> a(m);
        for (int j = 0; j < m; j++) {
            cin >> a[j];
        }        
        sort(a.begin(), a.end());
        a.erase(unique(a.begin(), a.end()), a.end());
        v.push_back(a);
    }

    int q;
    cin >> q;
    while (q--) {
        int a1, a2;
        cin >> a1 >> a2;
        a1 -= 1, a2 -= 1;
        vector<int> _union, _insect;
        set_union(v[a1].begin(), v[a1].end(), v[a2].begin(), v[a2].end(), inserter(_union, _union.begin()));
        set_intersection(v[a1].begin(), v[a1].end(), v[a2].begin(), v[a2].end(), inserter(_insect, _insect.begin()));
        double sz1 = _insect.size(), sz2 = _union.size();
        cout << fixed << setprecision(2) << sz1 / sz2 * 100 << "%" << "\n"[q == 0];
    }
    

    return 0;
}
//4.16
//4.8
//