Submission #545172

#	Time	Username	Problem	Language	Result	Execution time	Memory
545172		Zhora_004	The Xana coup (BOI21_xanadu)	C++17	5 / 100	1088 ms	7876 KiB

xanadu

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <unordered_set>
#include <queue>
#include <deque>
#include <string>
#include <sstream>
#include <iomanip>
#include <map>
#include <unordered_map>
#include <stack>
#include <cstdio>
#include <climits>
#include <tuple>
#include <ctime>
#include <cstring>
#include <numeric>
#include <functional>
#include <chrono>
#include <cassert>
#include <bitset>
//#include <bit>
//#include <ranges>
//#include <numbers>
#define itn int
#define sacnf scanf
#define sz(a) ((int)((a).size()))
// printf("%.10f\n", ans);
using ll = long long;
using namespace std;
const ll mod = 1e9 + 7;
const int N = 1e6 + 1, inf = 1e9;
int n;
vector<int> on;
vector<vector<int>> tree;


int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n;
    on = vector<int>(n);
    tree = vector<vector<int>>(n);
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin >> u >> v;
        tree[--u].push_back(--v);
        tree[v].push_back(u);
    }
    for (int i = 0; i < n; i++) cin >> on[i];
    int ans = 1e9;
    for (int mask = 0; mask < (1 << n); mask++)
    {
        vector<int> tmp = on;
        int cnt = 0;
        for (int i = 0; i < n; i++)
        {
            if ((mask >> i) & 1)
            {
                int u = n - i - 1;
                tmp[u] ^= 1;
                for (int& v : tree[u]) tmp[v] ^= 1; 
                cnt++;
            }
        }
        bool flag = 1;
        for (int i = 0; i < n; i++)
        {
            if (tmp[i])
            {
                flag = 0;
                break;
            }
        }
        if (flag) ans = min(ans, cnt);
    }
    if (ans == 1e9) cout << "impossible";
    else cout << ans;

    return 0;
}

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