Submission #784438

#	Time	Username	Problem	Language	Result	Execution time	Memory
784438		t6twotwo	Spring cleaning (CEOI20_cleaning)	C++17	28 / 100	1081 ms	11988 KiB

cleaning

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N, Q;
    cin >> N >> Q;
    vector<int> deg(N);
    vector<vector<int>> adj(N);
    for (int i = 0; i < N - 1; i++) {
        int x, y;
        cin >> x >> y;
        deg[--x]++;
        deg[--y]++;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    int cnt = 0, leaves = 0;
    vector<int> v(N), par(N, -1);
    auto dfs = [&](auto dfs, int x) -> void {
        if (deg[x] == 1) {
            v[x] = 1;
            leaves++;
        }
        for (int y : adj[x]) {
            if (y == par[x]) {
                continue;
            }
            par[y] = x;
            dfs(dfs, y);
            v[x] ^= v[y];
        }
        cnt += v[x];
    };
    dfs(dfs, 0);
    while (Q--) {
        int D;
        cin >> D;
        vector<int> a(D);
        for (int &p : a) {
            cin >> p;
            p--;
            if (deg[p]++ != 1) {
                leaves++;
                int x = p;
                while (x != -1) {
                    cnt += v[x] == 0 ? 1 : -1;
                    v[x] ^= 1;
                    x = par[x];
                }
            }
        }
        if (leaves % 2 == 1) {
            cout << -1 << "\n";
        } else {
            cout << 2 * (N - 1) - cnt + D<< "\n";
        }
        for (int p : a) {
            if (--deg[p] != 1) {
                leaves--;
                int x = p;
                while (x != -1) {
                    cnt += v[x] == 0 ? 1 : -1;
                    v[x] ^= 1;
                    x = par[x];
                }
            }
        }
    }
    return 6/22;
}

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