Submission #986296

#	Time	Username	Problem	Language	Result	Execution time	Memory
986296		dorjderem	The Xana coup (BOI21_xanadu)	C++17	0 / 100	1088 ms	7192 KiB

xanadu

#include <iostream>
#include <vector>
#include <queue>
#include <unordered_map>
#include <bitset>

using namespace std;

#define ull unsigned long long

int main()
{
    int n;
    cin >> n;

    vector<vector<int>> adj(n);
    for (int i = 0; i < n - 1; ++i)
    {
        int a, b;
        cin >> a >> b;
        adj[a - 1].push_back(b - 1);
        adj[b - 1].push_back(a - 1);
    }
    int tree = 0;
    for (int i = 0; i < n; i++)
    {
        int a;
        cin >> a;
        if (a)
            tree |= (1 << i);
    }
    int ans = 1e9;
    for (int bit = 0; bit < (1 << n); bit++)
    {
        int a = tree;
        for (int i = 0; i < n; i++)
        {
            if (bit & (1 << i))
            {
                a ^= (1 << i);
                for (int nxt : adj[i])
                {
                    a ^= (1 << nxt);
                }
            }
        }
        if (a == 0)
        {
            ans = min(ans, __builtin_popcount(bit));
        }
    }
    if (ans < 1e9)
        cout << ans << endl;
    else
        cout << "IMPOSSIBLE";
    return 0;
}

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