Submission #1235274

#	Time	Username	Problem	Language	Result	Execution time	Memory
1235274		badge881	Spring cleaning (CEOI20_cleaning)	C++20	28 / 100	1096 ms	10820 KiB

cleaning

#include <bits/stdc++.h>
using namespace std;

#define int long long
const int MAX_N = 100000;

vector<vector<int>> adj;
vector<int> parity, anc, cost = {2, 1};
int total_cost = 0;

int count_leaves(int u, int a)
{
    int s = 0;
    for (auto v : adj[u])
    {
        if (v != a)
        {
            anc[v] = u;
            s += count_leaves(v, u);
        }
    }
    if (s == 0)
        s = 1;

    total_cost += cost[s % 2];

    parity[u] = s % 2;
    return s;
}

void flip(int u)
{
    total_cost -= cost[parity[u]];
    parity[u] ^= 1;
    total_cost += cost[parity[u]];
    if (anc[u] != -1)
        flip(anc[u]);
}
signed main()
{
    cin.tie(NULL);
    ios_base::sync_with_stdio(false);
    int n, q;
    scanf("%lld%lld\n", &n, &q);
    adj.resize(n);
    parity.resize(n);
    anc.resize(n, -1);
    int node = 0;
    int deg = 0;

    for (int i = 0; i < n - 1; i++)
    {
        int a, b;
        scanf("%lld%lld\n", &a, &b);
        a--;
        b--;
        adj[a].push_back(b);
        adj[b].push_back(a);
        if (adj[a].size() > deg)
        {
            node = a;
            deg = adj[a].size();
        }
        if (adj[b].size() > deg)
        {
            node = b;
            deg = adj[b].size();
        }
    }

    int r = count_leaves(node, -1);
    for (int i = 0; i < q; i++)
    {
        int d;
        scanf("%lld\n", &d);
        vector<int> parents;
        for (int j = 0; j < d; j++)
        {
            int v;
            scanf("%lld\n", &v);
            v--;
            parents.push_back(v);
            adj[parents.back()].push_back(adj.size());
            total_cost++;
            if (adj[parents.back()].size() > 2)
            {
                flip(parents.back());
                r ^= 1;
            }
        }
        if (parity[node] == 1)
            printf("-1\n");
        else
            printf("%lld\n", total_cost - 2);

        adj.resize(n);
        for (auto e : parents)
        {
            if (adj[e].size() > 2)
            {
                flip(e);
                r ^= 1;
            }
            total_cost--;
            adj[e].pop_back();
        }
    }
}

Compilation message (stderr)

cleaning.cpp: In function 'int main()':
cleaning.cpp:44:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |     scanf("%lld%lld\n", &n, &q);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:54:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   54 |         scanf("%lld%lld\n", &a, &b);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~
cleaning.cpp:75:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   75 |         scanf("%lld\n", &d);
      |         ~~~~~^~~~~~~~~~~~~~
cleaning.cpp:80:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |             scanf("%lld\n", &v);
      |             ~~~~~^~~~~~~~~~~~~~

• 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