Submission #6791610

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Source Code Expand

#include<bits/stdc++.h>

using namespace std;

int main(){
int N; cin >> N;
  vector<int> A(N);
 for(int i = 0; i < N; i++){ cin >> A[i];}
  long double ans = 0;
  vector<int> arr(N);
  for(int i = 0; i < N; i++){  arr[i] = i;}
  int cnt = 0; // cnt means the counter of do-while( == N!)
  do{cnt++;
    vector<bool> flip(N,true);
    //true means a coin is on the above side while false means the opposite
    for(int i = 0; i < N - 1; i++){
      for(int j = i + 1; j < N; j++){
        if( !(A[arr[j]] % A[arr[i]])){ flip[arr[j]] = !flip[arr[j]];}
      }}
    
    for(int i = 0; i < N; i++){
      if(flip[i]){ ans++;}
    }
     
   
  }while( next_permutation(arr.begin(),arr.end()));
  
  cout << fixed << setprecision(10) << ans / cnt << endl; return 0;
}
  

Submission Info

Judge Result