Submission #1227147

#	Time	Username	Problem	Language	Result	Execution time	Memory
1227147		sitingfake	Amusement Park (CEOI19_amusementpark)	C++20	42 / 100	8 ms	1040 KiB

amusementpark

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

// define

#define execute cerr << " Time: " << fixed << setprecision(6) << (1.0 * clock() / CLOCKS_PER_SEC) << "s\n";
#define ll long long
#define ld double
#define ii pair<int,int>
#define se second
#define fi first
#define iii pair<int,ii>
#define all(v) v.begin(),v.end()
#define bit(x,i) (((x)>>(i))&1LL)
#define flip(x,i) ((x)^(1LL<<(i)))
#define ms(d,x) memset(d,x,sizeof(d))
#define sitingfake 1
#define orz 1

//constant

const ll mod = 1e9 + 7;
const long long linf = 4557430888798830399;
const int inf = 1061109567;
const int maxarr = 1e6 + 5;
const int dx[] = {0,1,-1,0};
const int dy[] = {1,0,0,-1};

template<typename T> bool maximize(T &a, const T &b)
{
    if(a < b) {a = b; return 1;}
    return 0;
}

template<typename T> bool minimize(T &a, const T &b)
{
    if(a > b) {a = b; return 1;}
    return 0;
}

inline void Plus(ll & a ,ll b)
{
    b %= mod;
    a += b;
    if(a >= mod) a -= mod;
    if(a < 0) a += mod;
    return;
}

inline void Mul(ll & a, ll b)
{
    a %= mod; b %= mod;
    a *= b;
    a %= mod;
    return;
}

//code
const int maxn = 20;

bool can[1 << 18];
ll dp[1 << 18];

int n , m;


void solve(void)
{
    cin >> n >> m;

    for(int mask = 0; mask < (1 << n); mask++)
        can[mask] = 1;
    for(int i = 1; i <= m; i++)
    {
        int u , v;
        cin >> u >> v;
        u-- ; v--;

        for(int mask = 1; mask < (1 << n); mask++)
        {
            if(bit(mask , u) && bit(mask , v)) can[mask] = 0;
        }
    }

    dp[0] = 1;

    for(int mask = 1; mask < (1 << n); mask++)
    {
        for(int submask = mask ; submask > 0; submask = mask &(submask - 1))
        {
            if(!can[submask]) continue;
            if(__builtin_popcount(submask) & 1) Plus(dp[mask] , dp[mask ^ submask]);
            else Plus(dp[mask] , -dp[mask ^ submask]);
        }
    }

    cout << (((dp[(1 << n) - 1] * m) % mod) * 500000004) % mod;
}
/**
**/
signed main()
{
   ios_base::sync_with_stdio(0);
   cin.tie(0);
   cout.tie(0);

   #define task ""

   if(fopen(task".inp","r"))
   {
       freopen(task".inp","r",stdin);
       freopen(task".out","w",stdout);
   }

   int tc; tc = 1;

   while(tc--) solve();

   //execute;
}

Compilation message (stderr)

amusementpark.cpp: In function 'int main()':
amusementpark.cpp:111:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |        freopen(task".inp","r",stdin);
      |        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
amusementpark.cpp:112:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |        freopen(task".out","w",stdout);
      |        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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