题解 | 记负均正

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

int main() {
    int sum = 0, n, a = 0, b = 0;
    cin >> n;
    for (int i = 1, x; i <= n; i++) {
        cin >> x;
        if (x > 0) a++, sum += x;
        else if (x < 0) b++;
    }
    cout << b << " " << fixed << setprecision(7) << (a ? 1.0 * sum / a : a) << endl;
}