LA3635 - Pie

My birthday is coming up and traditionally I'm

serving pie. Not just one pie, no, I have a number

N of them, of various tastes and of various sizes. F

of my friends are coming to my party and each of

them gets a piece of pie. This should be one piece

of one pie, not several small pieces since that looks

messy. This piece can be one whole pie though.

My friends are very annoying and if one of them

gets a bigger piece than the others, they start com-

plaining. Therefore all of them should get equally

sized (but not necessarily equally shaped) pieces,

even if this leads to some pie getting spoiled (which

is better than spoiling the party). Of course, I want

a piece of pie for myself too, and that piece should also be of the same size.

What is the largest possible piece size all of us can get? All the pies are cylindrical in shape and

they all have the same height 1, but the radii of the pies can be different.

Input

One line with a positive integer: the number of test cases. Then for each test case:

 One line with two integers N and F with 1  N, F  10000: the number of pies and the number

of friends.

 One line with N integers ri with 1  ri  10000: the radii of the pies.

Output

For each test case, output one line with the largest possible volume V such that me and my friends can

all get a pie piece of size V . The answer should be given as a oating point number with an absolute

error of at most 10

#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;
#define PI acos(-1)
const int MAXN = 10010;
double S[MAXN];
int N, F;
bool check(double mid)
{
int sum = 0;
for(int i=0; i<N; i++)
{
sum += floor(S[i]/mid);
}
return sum>=F+1;
}
int main()
{
int t, r;
scanf("%d",&t);
while(t--)
{

scanf("%d%d",&N,&F);
for(int i=0; i<N; i++)
{
scanf("%d",&r);
S[i] = r*r*PI;
}
double min1 = 0, max1 = 1e14, mid;
while(max1-min1>1e-5)
{
mid = (max1+min1)/2;
if(check(mid))
{
min1 = mid;
}else{
max1 = mid;
}
}
printf("%.4f\n",min1);
}
return 0;
}