Submission #556685

#	Time	Username	Problem	Language	Result	Execution time	Memory
556685		hoanghq2004	Spring cleaning (CEOI20_cleaning)	C++14	16 / 100	1086 ms	30168 KiB

cleaning

#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;

const int N = 1e5 + 10;

int n, q, ans;
set <int> g[N];
int sz[N];

void dfs(int u, int p) {
    if (g[u].size() <= 1 && p) {
        sz[u] = 1;
        return;
    }
    sz[u] = 0;
    for (auto v: g[u]) {
        if (v == p) continue;
        dfs(v, u);
        sz[u] += sz[v];
        ans += (sz[v] % 2 ? 1 : 2);
    }
}

void solve() {
    int m;
    cin >> m;
    for (int i = 1; i <= m; ++i) {
        int u;
        cin >> u;
        g[u].insert(i + n);
        g[i + n].insert(u);
    }
    int leaves = 0;
    for (int i = 1; i <= n + m; ++i)
        if (g[i].size() <= 1) ++leaves;
    if (leaves % 2 == 0) {
        dfs(1, 0);
        cout << ans << '\n';
    } else cout << -1 << '\n';

    for (int u = n + 1; u <= n + m; ++u) {
        for (auto v: g[u]) g[v].erase(u);
        g[u].clear();
    }
    ans = 0;
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n >> q;
    for (int i = 1; i < n; ++i) {
        int u, v;
        cin >> u >> v;
        g[u].insert(v);
        g[v].insert(u);
    }
    while (q--) 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