poj 1862

弱弱地排个序  然后过了 .....

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>

using namespace std;
double a[110];
int cmp(double x, double y)
{
    return x > y;
}
int main()
{
    int n;
    scanf("%d",&n);
    for(int i = 0; i < n; i++)
    {
        scanf("%lf",&a[i]);
    }
    sort(a, a+n, cmp);
    for(int i = 1; i < n; i++)
    {
        a[i] = 2*sqrt(a[i]*a[i-1]);
    }
    printf("%.3lf\n",a[n-1]);
    return 0;
}