http://acm.hdu.edu.cn/showproblem.php?pid=5003

记得排序后输出

#include <cstdio>

#include <cstring>

#include <iostream>

#include <string>

#include <vector>

#include <set>

#include <map>

#include <algorithm>

#include <cmath>

using namespace std;

const int N = 55;

int t, n, a[N];

int main() {

    scanf("%d", &t);

    while (t--) {

        scanf("%d", &n);

        for (int i = 0; i < n; i++)

            scanf("%d", &a[i]);

        sort(a, a + n);

        double ans = 0;

        for (int i = n - 1; i >= 0; i--) {

            ans += pow(0.95, n - 1 - i) * a[i];

        }

        printf("%.10lf\n", ans);

    }

    return 0;

}