Submission #1612918

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Source Code Expand

#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;

int main() {
    int n;
    cin >> n;
    int c[n];
    for (int i = 0; i < n; i++) {
        cin >> c[i];
    }

    double e = 0.0;
    for (int i = 0; i < n; i++) {
        int count = 0;
        for (int j = 0; j < n; j++) {
            if (i == j) continue;
            if (c[i] % c[j] == 0) count++;
        }
        if (count % 2) e += 1.0 / 2;
        else e += (count + 2.0) / (2 * count + 2.0);
    }
    printf("%.8lf\n", e);
    return 0;
}

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