Submission #930777

#	Time	Username	Problem	Language	Result	Execution time	Memory
930777		LucaIlie	Spring cleaning (CEOI20_cleaning)	C++17	28 / 100	1079 ms	14704 KiB

cleaning

#include <bits/stdc++.h>

using namespace std;

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

void dfs( int u, int p ) {
    parent[u] = p;
    for ( int v: adj[u] ) {
        if ( v == p )
            continue;
        children[u]++;
        dfs( v, u );
        leafs[u] += leafs[v];
    }
    leafs[u] += (children[u] == 0);
    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 );
    }

    int r = 1;
    while ( adj[r].size() == 1 )
        r++;
    ans = 0;
    dfs( r, 0 );

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

        cin >> d;
        for ( int i = 0; i < d; i++ ) {
            cin >> a[i];
            int v = a[i];
            change++;
            if ( children[v] == 0 ) {
                children[v]++;
                continue;
            }
            while ( v != 0 ) {
                change -= 2 - leafs[v] % 2;
                leafs[v]++;
                children[v]++;
                change += 2 - leafs[v] % 2;
                v = parent[v];
            }
        }

        change -= 2 - leafs[r] % 2;
        cout << (leafs[r] % 2 == 0 ? ans + change : -1) << "\n";

        for ( int i = 0; i < d; i++ ) {
            int v = a[i];
            if ( children[v] == 1 ) {
                children[v]--;
                continue;
            }
            while ( v != 0 ) {
                leafs[v]--;
                children[v]--;
                v = parent[v];
            }
        }
    }


    return 0;
}

• 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