Submission #1032631

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032631		Malix	The Xana coup (BOI21_xanadu)	C++14	5 / 100	1058 ms	7884 KiB

xanadu

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> tii;
typedef vector<ll> li;
typedef vector<li> lii;

#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define LSOne(s) ((s)&(-s))

ll INF=1e18+10;
int inf=1e9+10;
ll M=1e9+7;

int main() {   
//ios::sync_with_stdio(0);
//cin.tie(0);
//freopen("test_input.txt", "r", stdin);
//freopen("test_output.txt", "w", stdout);
   int n;cin>>n;
   vii a(n);
   REP(i,0,n-1){
    int x,y;
    cin>>x>>y;
    x--;y--;
    a[x].PB(y);
    a[y].PB(x);
   }
   vi b(n);
   REP(i,0,n)cin>>b[i];
   int ans=inf;
   int k=pow(2,n);
   REP(i,0,k){
    vi c=b;int d=0;
    REP(j,0,n)if(i&(1<<j)){
        c[j]=1-c[j];
        for(auto u:a[j])c[u]=1-c[u];
        d++;
    }
    bool flag=1;
    REP(j,0,n)if(c[j]==1)flag=0;
    if(flag)ans=min(ans,d);
   }

   if(ans==inf)cout<<"impossible";
   else cout<<ans;
}

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