Submission #1444840

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Source Code Expand

#include <iostream>
#include <vector>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <cstdio>

using namespace std;
using llng = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vs = vector<string>;
template<class T> using hset = unordered_set<T>;
template<class Key, class T> using hmap = unordered_map<Key, T>;

int main() {
    int N; cin >> N;
    vi c(N); for (int i=0; i<N; i++) cin >> c[i];
    int d;
    double e = 0;
    for (int i=0; i<N; i++) {
        d = 0;
        for (int j=0; j<N; j++) {
            if (j == i) continue;
            if (c[i] % c[j] == 0) d++;
        }
        e += (double)(d/2 + 1)/(d+1);
    }
    printf("%lf\n", e);
    return 0;
}

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