Submission #866972

#	Time	Username	Problem	Language	Result	Execution time	Memory
866972		Ahmed_Solyman	The Xana coup (BOI21_xanadu)	C++14	0 / 100	3 ms	6260 KiB

xanadu

/*
In the name of Allah
made by: Ahmed_Solyman
*/
#include <bits/stdc++.h>
#include <ext/rope>
 
using namespace std;
using namespace __gnu_cxx;
#pragma GCC optimize("-Ofast")
#pragma GCC optimize("-O1")
//-------------------------------------------------------------//
typedef long long ll;
typedef unsigned long long ull;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define PI acos(-1)
#define lb lower_bound
#define ub upper_bound
#define endl '\n'
#define all(v) v.begin(),v.end()
#define allr(v) v.rbegin(),v.rend()
#define sum_to(n) (n*(n+1))/2
#define pb push_back
#define pf push_front
#define fil(arr,x) memset(arr,x,sizeof(arr))
const ll mod=1e9+7;
int dx[8]={0,1,0,-1,1,1,-1,-1};
int dy[8]={1,0,-1,0,1,-1,-1,1};
//-------------------------------------------------------------//
ll lcm(ll a,ll b)
{
    return (max(a,b)/__gcd(a,b))*min(a,b);
}
void person_bool(bool x)
{
    cout<<(x?"YES":"NO")<<endl;
}
const int N=1e5+5;
vector<int>adj[N],color(N);
ll n,dp[N][2][2];
ll solve(int i,int c,int rev,int p){
	ll &ret=dp[i][c][rev];
	if(~ret)return ret;
	ret=1e9;
	for(int mask=0;mask<(1<<(adj[i].size()-1+(i==1)));mask++){
		int j=0;
		ll cost=0;
		int u=c;
		for(auto ch:adj[i]){
			if(ch==p)continue;
			bool b=(1<<j)&mask;
			if(b){
				u^=1;
			}
			cost+=solve(ch,b^rev^color[ch],b,i);
			j++;
		}
		if(!u){
			ret=min(ret,cost+rev);
		}
	}
	return ret;
}
int main()
{
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    #ifndef ONLINE_JUDGE
    freopen("input.in", "r", stdin);
    freopen("output.out", "w", stdout);
    #endif
    fast
    fil(dp,-1);
    int n;cin>>n;
    for(int i=0;i<n-1;i++){
    	int u,v;cin>>u>>v;
    	adj[u].push_back(v);
    	adj[v].push_back(u);
    }
    for(int i=1;i<=n;i++)cin>>color[i];
    int ans=min(solve(1,color[1],0,0),solve(1,!color[1],1,0));
	if(ans>=1e9){
		cout<<"IMPOSSIBLE"<<endl;
	}
    else cout<<ans<<endl;
    return 0;
}

Compilation message (stderr)

xanadu.cpp: In function 'int main()':
xanadu.cpp:69:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |     freopen("input.in", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
xanadu.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |     freopen("output.out", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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