Submission #574145

#	Time	Username	Problem	Language	Result	Execution time	Memory
574145		talant117408	The Xana coup (BOI21_xanadu)	C++17	5 / 100	1084 ms	7888 KiB

xanadu

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
 
#define pb                  push_back
#define mp                  make_pair
#define all(v)              (v).begin(),(v).end()
#define sz(v)               int((v).size())
#define do_not_disturb      ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl                '\n'
 
int mod = 1e9+7;
 
ll modulo(ll a) {
    return ((a % mod) + mod) % mod;
}
 
ll add(ll a, ll b) {
    return modulo(a + b);
}
 
ll mult(ll a, ll b) {
    return modulo(a * b);
}
 
ll binpow(ll a, ll b) {
    ll res = 1;
    while (b) {
        if (b&1) {
            res = mult(res, a);
        }
        a = mult(a, a);
        b >>= 1;
    }
    return res;
}

const int N = 1e5+7;
vector <int> graph[N];
int color[N];

void check(int n) {
    int mn = 2e9;
    for (int mask = 0; mask < (1 << n); mask++) {
        vector <int> c(n);
        for (int i = 0; i < n; i++) c[i] = color[i];
        for (int i = 0; i < n; i++) {
            if (mask & (1 << i)) {
                c[i] ^= 1;
                for (auto to : graph[i]) {
                    c[to] ^= 1;
                }
            }
        }
        int flag = 0;
        for (int i = 0; i < n; i++) flag |= c[i];
        if (!flag) {
            mn = min(mn, __builtin_popcount(mask));
        }
    }
    if (mn < 2e9) {
        cout << mn << endl;
        exit(0);
    }
}

void solve() {
    int n;
    cin >> n;
    for (int i = 0; i < n-1; i++) {
        int a, b;
        cin >> a >> b;
        a--; b--;
        graph[a].pb(b);
        graph[b].pb(a);
    }
    for (int i = 0; i < n; i++) {
        cin >> color[i];
    }
    check(n);
    cout << "impossible" << endl;
}

int main() {
    do_not_disturb
    
    int t = 1;
    //~ cin >> t;
    while (t--) {
        solve();
    }
    
    return 0;
}

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