Submission #930765

#	Time	Username	Problem	Language	Result	Execution time	Memory
930765		LucaIlie	Spring cleaning (CEOI20_cleaning)	C++17	34 / 100	1090 ms	20532 KiB

cleaning

#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 2e5;
int leafs[MAX_N + 1], a[MAX_N];
vector<int> adj[MAX_N + 1];
int ans;

void dfs( int u, int p ) {
    leafs[u] = (adj[u].size() == 1);
    for ( int v: adj[u] ) {
        if ( v == p )
            continue;
        dfs( v, u );
        leafs[u] += leafs[v];
    }
    ans += 2 - leafs[u] % 2;
}

int main() {
    int n, q;

    cin >> n >> q;
    for ( int i = 0; i < n - 1; i++ ) {
        int u, v;
        cin >> u >> v;
        adj[u].push_back( v );
        adj[v].push_back( u );
    }



    for ( int i = 0; i < q; i++ ) {
        int d;

        cin >> d;
        for ( int i = 0; i < d; i++ ) {
            cin >> a[i];
            int p = a[i], v = n + 1 + i;
            adj[p].push_back( v );
            adj[v].push_back( p );
        }

        int r = 1;
        while ( adj[r].size() == 1 )
            r++;
        ans = 0;
        dfs( r, 0 );
        ans -= 2 - leafs[r] % 2;
        cout << (leafs[r] % 2 == 0 ? ans : -1) << "\n";

        for ( int i = d - 1; i >= 0; i-- ) {
            int p = a[i], v = n + 1 + i;
            adj[p].pop_back();
            adj[v].pop_back();
        }
    }


    return 0;
}

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