Submission #1030429

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Source Code Expand

#include <bits/stdc++.h>
 
#define REP(i,n) for(int i=0; i<(int)(n); ++i)
#define RREP(i,n) for(int i=(int)(n); i>=0; --i)
#define FOR(i,k,n) for(int i=(k);i<(int)(n);++i)
typedef long long int ll;
using namespace std;

int main(void) {
    int N;
    cin >> N;
    vector<int> C(N);
    REP(i, N) cin >> C[i];
    double ans = 0;
    REP(i, N) {
        int S = 0;
        REP(j, N) {
            if(i != j && C[i] % C[j] == 0) S++;
        }
        if(S%2 == 1) ans += 0.5;
        else ans += double(S+2.0)/(2.0*S+2.0);
    }
    printf("%.10f\n", ans);
}

Submission Info

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