Submission #399098

#	Time	Username	Problem	Language	Result	Execution time	Memory
399098		Jarif_Rahman	The Xana coup (BOI21_xanadu)	C++17	0 / 100	1088 ms	14524 KiB

xanadu

#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
const ll inf = 1e9;
int n;
ll ans = inf;
vector<int> ss;
vector<vector<int>> v;
vector<int> state;
void bruteforce(int k){
    if(k == n){
        auto new_state = state;
        for(int x: ss){
            new_state[x] = !new_state[x];
            for(int y: v[x]) new_state[y] = !new_state[y];
            if(all_of(new_state.begin(), new_state.end(), [&](int z){return z==0;})) ans = min(ans, (ll)ss.size());
        }
        return;
    }
    ss.pb(k);
    bruteforce(k+1);
    ss.pop_back();
    bruteforce(k+1);
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cin >> n;
    v.resize(n);
    state.resize(n);
    for(int i = 0; i < n-1; i++){
        int a, b; cin >> a >> b; a--, b--;
        v[a].pb(b);
        v[b].pb(a);
    }
    for(int &x: state) cin >> x;
    bruteforce(0);
    if(ans >= inf) cout << "impossible\n";
    cout << ans << "\n";
}

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