What am I doing wrong ?
#include<bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
#define ll long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define vi vector<int>
#define mii map<int,int>
#define fab(i,a,b) for(int i=a;i<b;i++)
#define pqb priority_queue<int>
#define pqs priority_queue<int,vi,greater<int> >
#define setbits(x) __builtin_popcountll(x)
#define zrobits(x) __builtin_ctzll(x)
#define mod 1000000007
#define inf 1e18
#define ps(x,y) fixed<<setprecision(y)<<x
#define mk(arr,n,type) type *arr=new type[n];
#define w(x) int x; cin>>x; while(x--)
void k_t_p()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
}
long double ans=0;
bool isvalid(long double vol,int c,vector<long double> &v)
{
int cnt=0;
for(int i=0;i<v.size();i++)
{
cnt +=(int) (v[i]/vol);
// cout<<vol<<" "<<cnt<<endl;
}
if(cnt>=c) return true;
else
{
return false;
}
}
void solve(int n,int c,vector<long double> &v)
{
long double lo=0;
long double hi=v[n-1];
while(lo<=hi)
{
long double mid=lo +(hi-lo)/2;
if (isvalid(mid,c+1,v))
ans=max(ans,mid),lo=mid+0.001;
else
hi=mid-0.001;
//cout<<mid<<" "<<ans<<endl;
}
}
int main()
{
k_t_p();
w(t)
{
int n,c;
cin>>n>>c;
vector<long double> v(n);
fab(i,0,n)
cin>>v[i];
long double pi=acos(-1.0);
//cout<<pi<<endl;
fab(i,0,n)
v[i]=pi*v[i]*v[i];
sort(v.begin(),v.end());
solve(n,c,v);
cout<<fixed<<setprecision<<ans<<endl;
ans=0;
}
return 0;
}