Wrong Answer.
wrong answer 
The answer is wrong: 
expected = 0.650000, 
found = 0.660000

Wrong Answer.
wrong answer 
The answer is wrong: 
expected = 0.660000, 
found = 0.670000

#include<bits/stdc++.h>
using namespace std;
const int N=1e4+10;
const double eps=1e-4;
double a[N];
int n,k;
int f(double x){
	int p=0;
	for(int i=1;i<=n;++i)
		p+=a[i]/x;
	return p;
}
int main(){
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;++i)
		scanf("%lf",a+i);
	double l=0,r=1e9,mid;
	while(r-l>=eps){
		mid=(l+r)/2;
		int fmid=f(mid);
		//printf("%lf  %d\n",mid,fmid);
		if(fmid<k)
			r=mid;
		else
			l=mid;
	}
	printf("%.2lf",l);
	return 0;
}