每周花费

#include<cstdio>
#include<algorithm>
#include<cmath> 
using namespace std;
#define PI acos(-1)
#define EPS 1e-6
double B[10000];
int main(){
int n,N,f,r;
double left=0,right=0;
scanf("%d",&n);
while(n--){
    scanf("%d%d",&N,&f);
    for(int i=1;i<=N;i++){
    scanf("%d",&r);
    B[i]=PI*r*r;    
    if(right<B[i])right=B[i];
    }
    while(right-left>=EPS){
        double mid=(right+left)/2.0;
        int sum=0;
        for(int i=1;i<=N;i++){
            sum+=(int)(B[i]/mid);
        }
        if(sum>=f+1)left=mid;
        else right=mid;
    }
    printf("%.4lf\n",left);
    left=0;
    
}
    return 0;
}