Submission #574281

#	Time	Username	Problem	Language	Result	Execution time	Memory
574281		moday_morning	The Xana coup (BOI21_xanadu)	C++17	5 / 100	1085 ms	16104 KiB

xanadu

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 1e9, N = 1e5 + 5;

vector <vector <int> > a;
int minn = INF, n;
vector <int> v, point;
void checker (int validator) {
    if(validator == n) {
        vector <int> p = point;
        for (auto i : v) {
            p[i] = !p[i];
            for (auto pos : a[i]) {
                p[pos] = !p[pos];
            }
            if (all_of(p.begin(), p.end(), [&](int z) { return z == 0; })) {
                minn = min(minn, (int)v.size());
            }
        }
    }
    else {
        v.push_back(validator);
        checker(validator + 1);
        v.pop_back();
        checker(validator + 1);
    }
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n;
    a.resize(n);
    for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
        u--;
        v--;
        a[u].push_back(v);
        a[v].push_back(u);
    }
    point.resize(n);
    for (int i = 0; i < n; i++) {
        cin >> point[i];
    }
    checker(0);
    if (minn >= INF) {
        cout << "impossible\n";
    }
    else {
        cout << minn << "\n";
    }
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 15
• Subtask 3: 0 / 10
• Subtask 4: 0 / 40
• Subtask 5: 0 / 30