题解 | 记负均正

#include <iostream>
#include <vector>
#include <iomanip>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<double> nums(n);
    int count_negative = 0, count_positive = 0;
    double sum_positive = 0;
    for(int i = 0; i < n; ++i) {
        cin >> nums[i];
        if(nums[i] < 0) ++count_negative;
        else if(nums[i] > 0) {
            sum_positive += nums[i];
            ++count_positive;
        }
    }
    double average;
    if(!count_positive) average = 0;
    else average = sum_positive / count_positive;
    cout << count_negative << " " << fixed << setprecision(12) << average << endl;
    return 0;
}