PIE  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 complaining. 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 r_{i} with 1 ≤ r_{i} ≤ 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 floating point number with an absolute error of at most 10^{3}.
Example
Input: 3 3 3 4 3 3 1 24 5 10 5 1 4 2 3 4 5 6 5 4 2 Output: 25.1327 3.1416 50.2655
hide comments
ayush5148:
20160826 23:12:23
float costed me 2 WA, use double in c/c++... Last edit: 20160826 23:14:33 

suraj_:
20160822 12:37:28
AC in one go..... 

adichd123:
20160815 12:36:42
use printf please...cout gives WA! 

Akshay Damle:
20160421 16:17:55
Nice question! You don't need long double  double is fine. Just use a precise value of PI. 

Deepak :
20160302 21:23:56
finally AC..nice question. 

Avik Sarkar:
20160122 14:51:15
Use integer Calculation for Friends .... As there is no matter whatever It will be some Wastage . 

rc_alex36:
20151229 11:03:58
I just defined pi as acos(1) and it worked 

agaurav77:
20150927 10:16:49
Shafaet is right, WAs may occur due to an imprecise value of Pi, use a significantly precise value like he gave. AC :) 

Devashish:
20150905 00:27:08
Size same by volume of the pie or area of the pie(considering horizontal cuts are not valid)? help? 

Utsav Sinha:
20150809 16:01:51
Used double and got ac in C 
Added by:  overwise 
Date:  20071002 
Time limit:  0.751s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  ACM ICPC NWERC 2006 