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
anuj0503:
20160115 18:59:55
sorting !! 

dokz:
20160115 06:58:51
Getting a runtime error without a reason on C#. At the same time, it runs great on my PC and ideone.


Junaid:
20160111 10:30:54
Same logic in JAVA: TLE in C++:AC...don't know why... 

damsehgal:
20160103 17:20:22
typo costed me WA


sarangs:
20151226 15:57:48
Should be moved to tutorial....too easy 

BRAIN:
20151226 04:04:53
O(nlogn + n) 

Vineeth Reddy:
20151220 15:17:16
was getting TLE then changed logic to O(logn+n) AC:) My 50th


Ravi Chandra:
20150921 18:25:09
Easy One 

Shivam Singh:
20150820 14:36:51
(i+K)<N instead of (i+K)<=N was causing WA :P


Sumit Paroothi:
20150812 07:27:05
easy one! 
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 