Submission #1673677

---

Source Code Expand

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

#define REP(i,n) for(int i=0;i<n;i++)
#define REPR(i,n) for(int i=n;i>=0;i--)
#define FOR(i,m,n) for(int i=m;i<n;i++)
#define EPS (1e-7)
#define MAX_N 100

typedef long long ll;

typedef pair<int,int>P;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};

int main(){	
	int n;
	cin>>n;
	vector<int> c(n);
	REP(i,n){
		cin>>c[i];
	}
	int ans=0;
	sort(c.begin(),c.end());
	int comb=0;
	do{
		REP(i,n){
			int count=0;
			REP(j,i){
				if(c[i]>=c[j] && c[i]%c[j]==0)count++;
			}
			if(count%2==0)ans++;
		}
		comb++;
	}while(next_permutation(c.begin(),c.end()));
	cout<<(double)ans/comb<<endl;
	return 0;
}

Submission Info

Judge Result