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;
}