AMR10G  Christmas Play
My kid's kindergarten class is putting up a Christmas play. (I hope he gets the lead role.) The kids are all excited, but the teacher has a lot of work. She has to produce costumes for a scene with K soldiers. She wants to buy all the costumes in the same size, allowing for some small amount of length alteration to be done by the kids' parents later. So she has taken all the kids' height measurements. Can you help her select K kids from her class of N to play the soldier role, such that the height difference between the tallest and shortest in the group is minimized, and alternations will be easiest? Tell her what this minimum difference is.
INPUT
The first line contains the number of test cases T. T test cases follow each containing 2 lines.
The first line of each test case contains 2 integers N and K.
The second line contains N integers denoting the height of the N kids.
OUTPUT
Output T lines, each line containing the required answer for the corresponding test case.
CONSTRAINTS
T <= 30
1 <= K <= N <= 20000
1 <= height <= 1000000000
SAMPLE INPUT
3 3 1 2 5 4 3 2 5 2 4 3 3 2 5 4SAMPLE OUTPUT
0 1 3EXPLANATION
In the first test case, the teacher needs to only select 1 kid and hence she can choose any kid since the height difference is going to be 0.
In the second test case, the teacher can choose kids with height 4 and 5.
In the third test case, the teacher is forced to choose all 3 kids and hence the answer = 52 = 3
hide comments
Anvesh Kumar Arrabochu:
20150107 16:43:21
Submitted same code two times, got WA at first and AC, the second time and heights better be in nano metres or something :P 

Madhur Bhargava:
20141118 09:25:54
* O(NlogN+ N) time AC!!! Last edit: 20141118 09:26:09 

Anubhav Mathur:
20140904 16:02:02
Judge is drunked, with same code 5 compilation errors then ac o.O 

Diptesh Patel:
20140801 09:05:43
"0.14"sec in C++4.3.2 :D Last edit: 20140801 09:06:03 

Baojun Wang:
20140726 07:15:36
haskell O(nlogn+n) = TLE?


Arjun Verma:
20140722 11:02:22
very easy with stl ! 

Rajat (1307086):
20140706 23:48:20
Despite being a served dish,not reading the ques properly caused me several wrong answer.


j1k7_7(JaskamalKainth):
20140701 19:49:27
0.18sec in C.:D 

Rachit:
20140627 23:19:18
spoj is drunk


pandu ranga rao:
20140612 15:41:31
i got AC after 3 WA.comments helped me. 
Added by:  Varun Jalan 
Date:  20101213 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 
Resource:  ICPC Asia regionals, Amritapuri 2010 