Submission #1230044

#	Time	Username	Problem	Language	Result	Execution time	Memory
1230044		RakhimovAmir	Spring cleaning (CEOI20_cleaning)	C++20	9 / 100	37 ms	7612 KiB

cleaning

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
inline void debugMode() {
    #ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
    #endif // ONLINE_JUDGE
}

const int N = 1e5 + 10;
vector<int> v[N];
int n, q;
int c[N], add[N], f[N], p[N], k;
int res, root;

void dfs(int x, int p) {
    ::p[x] = p;
    c[x] = (v[x].size() == 1);
    k += c[x];
    for (auto to : v[x]) {
        if (to == p)
            continue;
        dfs(to, x);
        c[x] += c[to];
    }
    c[x] %= 2;
    if (c[x] == 0)
        c[x] = 2;
    res += (x == root ? 0 : c[x]);
}

void update(int x) {
    if (x == root)
        return;
    res -= c[x];
    if (c[x] == 2)
        c[x] = 1;
    else
        c[x] = 2;
    res += c[x];
}

void solve() {
    cin >> n >> q;
    for (int i = 0; i < n - 1; i++) {
        int a, b;
        cin >> a >> b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for (int i = 1; i <= n; i++) {
        if (v[i].size() > 1) {
            root = i;
            break;
        }
    }
    // cout << root << "\n";
    dfs(root, root);
    while (q--) {
        int d;
        cin >> d;
        vector<int> g(d);
        for (auto &i : g) {
            cin >> i;
            if (v[i].size() + f[i] == 1) {
                f[i]++;
                continue;
            }
            f[i]++;
            update(i);
            k++;
        }
        cout << (k % 2 ? -1 : res + d) << "\n";
        for (auto &i : g) {
            f[i]--;
            if (v[i].size() + f[i] == 1) {
                continue;
            }
            update(i);
            k--;
        }
    }
}

signed main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    // debugMode();
    int $ = 1;
    // cin >> $;
    while ($--) {
        solve();
    }
}

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