Submission #2181919

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Source Code Expand

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

#define INF 1.1e9
#define LINF 1.1e18
#define FOR(i,a,b) for (int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define BIT(x,n) bitset<n>(x)
#define PI 3.14159265358979323846

typedef long long ll;
typedef pair<int,int> P;
typedef pair<P,int> PP;
typedef pair<ll,int> Pli;

//-----------------------------------------------------------------------------

int n,c[100];
double ans,d=1;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	cin>>n;
	REP(i,n) cin>>c[i];

	REP(i,n) {
		int cnt=0;
		REP(j,n) if(c[i]%c[j]==0) cnt++;
		cnt--;
		if(cnt&1) ans+=0.5;
		else ans+=1.*(cnt/2)/(cnt+1);
		//printf("%.10f\n",ans);
	}
	printf("%.10f\n",n-ans);

	return 0;
}

Submission Info

Judge Result