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
ab_bh:
20160618 14:28:59
finally got it!!!!....easy question....no tricky test cases.


deepukps:
20160614 11:20:25
Are there any tricky test cases ?


entcat:
20160227 16:14:11
are the individual heights distinct? 

prateek1985:
20160205 15:06:11
java users do use fast i/o for (nlogn +n) 

mero_iitdhn:
20160130 19:00:26
use stl for sorting and long long instead of double 

Devashish Mathur:
20160126 18:32:06
Initially took a completely different track... Got ac in second try.. 

sharath_111:
20160126 18:22:12
stl ;) sorting 

akshayvenkat:
20160126 10:49:13
simple way to overcome TLE.


try2catch:
20160124 06:01:26
java giving TLE :(... C++ not!


rishabh_1997:
20160116 04:17:32
Use quick sort.....using bubble sort TLE... :( 
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 