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
Stefan:
20120602 17:28:29
What's the answer of:


Santiago Palacio:
20120112 19:36:30
If you are getting TLE with T(nlog(n)+n) look for I/O optimizations. 

Hazem:
20111008 15:08:36
am getting WA


sri:
20111005 19:35:51
am getting tle


sri:
20110223 14:41:45
superb question.... 

Manpreet Singh:
20110114 10:11:14
nice one for python 

numerix:
20110112 21:56:28
Impossible with Python 3 because of too much i/o.

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 