Submission #1993049

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Source Code Expand

#include <algorithm>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <map>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <list>
#include <cstdio>
#define INF 1000000000
#define MOD 1000000007ll
#define EPS 1e-10
#define REP(i,m) for(long long i=0; i<m; i++)
#define FOR(i,n,m) for(long long i=n; i<m; i++)
#define DUMP(a) for(long long dump=0; dump<(ll)a.size(); dump++) { cout<<a[dump]; if(dump!=(ll)a.size()-1) cout<<" "; else cout<<endl; }
#define ALL(v) v.begin(),v.end()
#define pb push_back
using namespace std;
typedef long long int ll;
typedef pair<ll, ll> P;
typedef long double ld;
using namespace std;
 
int main(){
	int n;
	cin >> n;
	int a[n];
	REP(i, n) cin >> a[i];
	int div[n] = { };
	REP(i, n){
		REP(j, n){
			if(i != j && a[i] % a[j] == 0) div[i]++;
		}
	}
	ld x = 0;
	REP(i, n){
		if(div[i] == 0) x += 1;
		else if(div[i] % 2 == 1) x += 0.5;
		else x += (((double)div[i] / 2) + 1) / ((double)div[i] + 1.0);
	}
	cout << setprecision(16) << x << endl;
 	return 0;
}

Submission Info

Judge Result