Submission #1229977

#	Time	Username	Problem	Language	Result	Execution time	Memory
1229977		RakhimovAmir	Spring cleaning (CEOI20_cleaning)	C++20	16 / 100	1095 ms	12360 KiB

cleaning

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
inline void debugMode() {
    #ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    #endif // ONLINE_JUDGE
}

const int N = 1e5 + 10;
vector<int> v[N];
int c[N];
int res, root;

void dfs(int x, int p) {
    c[x] = (v[x].size() <= 1);
    for (auto to : v[x]) {
        if (to == p)
        continue;
        dfs(to, x);
        c[x] += c[to];
    }
    // cout << "x: " << x << " " << c[x] << "\n";
    if (x != root)
        res += (c[x] % 2 == 1 ? 1 : 2);
}

void solve() {
    int n, q;
    cin >> n >> q;
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for (int i = 1; i <= n; i++) {
        if (v[i].size() > 1) {
            root = i;
            break;
        }
    }
    // cout << root << "\n";
    while (q--) {
        int d;
        cin >> d;
        vector<int> g(d);
        int nw = n;
        for (auto &i : g) {
            cin >> i;
            v[i].push_back(++nw);
        }
        res = 0;
        dfs(root, root);
        cout << (c[root] % 2 == 1 ? -1 : res) << "\n";
        for (auto i : g) {
            v[i].pop_back();
        }
    }
}

signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    // debugMode();
    int $ = 1;
    // cin >> $;
    while ($--) {
        solve();
    }
}

• Subtask 1: 0 / 0
• Subtask 2: 0 / 9
• Subtask 3: 0 / 9
• Subtask 4: 16 / 16
• Subtask 5: 0 / 19
• Subtask 6: 0 / 17
• Subtask 7: 0 / 30