Submission #986217

#	Time	Username	Problem	Language	Result	Execution time	Memory
986217		dorjderem	The Xana coup (BOI21_xanadu)	C++17	0 / 100	620 ms	524288 KiB

xanadu

#include <iostream>
#include <vector>
#include <queue>
#include <tuple>
#include <algorithm>

using namespace std;

int main() {
    int n;
    cin >> n;
    
    vector<vector<int>> adj(n);
    int a, b;
    for (int i = 0; i < n - 1; ++i) {
        cin >> a >> b;
        --a; --b; // Convert to zero-based index
        adj[a].push_back(b);
        adj[b].push_back(a);
    }

    vector<bool> state(n);
    for (int i = 0; i < n; ++i) {
        int temp;
        cin >> temp;
        state[i] = (temp == 1);
    }

    bool found = false;
    for (int i = 0; i < n; ++i) {
        queue<pair<int, vector<bool>>> q;
        q.push(make_pair(i, state));
        
        int level = 0;
        while (!q.empty() && level < 20) {
            int q_size = q.size();
            for (int j = 0; j < q_size; ++j) {
                auto front = q.front();
                q.pop();
                
                int node = front.first;
                vector<bool> current_state = front.second;
                
                if (all_of(current_state.begin(), current_state.end(), [](bool v) { return !v; })) {
                    cout << level << endl;
                    return 0;
                }

                current_state[node] = !current_state[node];
                for (int neighbor : adj[node]) {
                    current_state[neighbor] = !current_state[neighbor];
                }

                for (int k = 0; k < n; ++k) {
                    if (k != node) {
                        q.push(make_pair(k, current_state));
                    }
                }
            }
            ++level;
        }
    }

    if (!found) {
        cout << "IMPOSSIBLE" << endl;
    }

    return 0;
}

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