Submission #945553

#	Time	Username	Problem	Language	Result	Execution time	Memory
945553		vjudge1	Amusement Park (CEOI19_amusementpark)	C++17	7 / 100	14 ms	49248 KiB

amusementpark

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
 
bool YES(bool f){ if(f) cout << "Yes\n" ; else cout << "No\n" ; return f ; }
void YES(){YES(1);}
void NO(){YES(0);}
void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
//#define ordered_set tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ios ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0);
#define int long long
#define ld long double
#define pii pair <int , int>
#define all(x) x.begin() , x.end()
#define ff first
#define ss second
#define endl '\n'
 
const int N = 1e6 + 5 ;
const int inf = 1e16 ;
const int mod = 1e9 + 8 ;
const double eps = 1e-8 ;
 
template <class T>
bool chmax( T& x , const T& y ){
  bool f = 0 ;
  if ( x < y ) x = y , f = 1 ;
  return f ;
}
template <class T>
bool chmin( T &x , const T &y ){
  bool f = 0 ;
  if ( x > y ) x = y , f = 1 ;
  return f ;
}
 
//code
 
int n , m ;
vector <int> g[N] , r[N] ;
vector <pii> vec ;
bool vis[N] , ch[N] ;

bool dfs ( int v ){
	vis[v] = 1 , ch[v] = 1 ;
	for ( auto to : g[v] ){
		if ( ch[to] ) return 1 ;
		if ( !vis[to] && dfs(to) ) return 1 ;
	} ch[v] = 0 ;
	return 0 ;
}

void solve(){
	
	cin >> n >> m ;
	for ( int i = 0 ; i < m ; i ++ ){
		int x , y ; cin >> x >> y ;
		vec.push_back({x,y}) ;
	} int ans = 0 ;
	for ( int i = 0 ; i < ( 1 << m ) ; i ++ ){
		for ( int j = 1 ; j <= n ; j ++ ) g[j].clear() , vis[j] = 0 , ch[j] = 0 ;
		for ( int j = 0 ; j < m ; j ++ ){
			if ( ( 1 << j ) & i ) g[vec[j].ss].push_back(vec[j].ff) ;
			else g[vec[j].ff].push_back(vec[j].ss) ;
		}
		if ( !dfs(1) ){
			int res = 0 ;
			for ( int j = 0 ; j < m ; j ++ ) if ( (1<<j)&i ) res ++ ;
			ans = (ans+res)%mod ;
		}
	}
	cout << ans ;
}

signed main(){
    ios ;
	int t = 1 ;
	//cin >> t ;
	while ( t -- ) solve() ;
}

Compilation message (stderr)

amusementpark.cpp: In function 'void fopn(std::string)':
amusementpark.cpp:10:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 | void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
amusementpark.cpp:10:72: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 | void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                                                                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 0 / 12
• Subtask 3: 0 / 23
• Subtask 4: 0 / 21
• Subtask 5: 0 / 37