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
shadan_amir1:
20190104 12:12:57
MergeSort+WindowSliding=MERRY Christmas!! 

adipat:
20181020 10:00:07
Easy problem. First sort in increasing order, then loop from i till i+k < n. Find the minimum of heights[i+k1]heights[i]. Basically we need to find the minimum difference between two end points such that there are k elements between them. 

pigpork:
20180613 14:07:50
printf ("Follow my Instagram!"); 

payal2621:
20180207 17:20:32
guys search for window technique on geeks for geeks dont copy the code just understand the example


sonuverma:
20171111 08:57:05
use quickSort in C 

madhur4127:
20171020 18:37:20
Another brute force problem! 

rehanrahi:
20171004 15:17:33
guys if you are stuck then simply use window sliding technique .it might be useful 

touchstone:
20170701 16:30:55
AC in 1 go :D is this even a question ? :P (timepass) 

ramesh_961:
20170622 18:04:32
AC in one go!! Use Merge sort!! 

shauryauppal:
20170608 22:33:25
step1 >sort(arr)

Added by:  Varun Jalan 
Date:  20101213 
Time limit:  0.635s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 
Resource:  ICPC Asia regionals, Amritapuri 2010 