AGGRCOW - Aggressive cows


Farmer John has built a new long barn, with N (2 <= N <= 100,000) stalls. The stalls are located along a straight line at positions x1 ... xN (0 <= xi <= 1,000,000,000).

His C (2 <= C <= N) cows don't like this barn layout and become aggressive towards each other once put into a stall. To prevent the cows from hurting each other, FJ wants to assign the cows to the stalls, such that the minimum distance between any two of them is as large as possible. What is the largest minimum distance?

Input

t – the number of test cases, then t test cases follows.
* Line 1: Two space-separated integers: N and C
* Lines 2..N+1: Line i+1 contains an integer stall location, xi

Output

For each test case output one integer: the largest minimum distance.

Example

Input:

1
5 3
1
2
8
4
9

Output:

3

Output details:

FJ can put his 3 cows in the stalls at positions 1, 4 and 8,
resulting in a minimum distance of 3.


hide comments
horizon121: 2017-05-11 14:06:06

This is the best problem for BS.You will realise how to implement BS

mdaqib: 2017-04-17 05:02:36

@ shingotem,In 1-4-8 ,8-4=4 is also not equal to 3. 4-1 = 3.so you have to find atleast the minimum distance

jxiong: 2017-04-04 05:53:13

Poor Scala Compiling. Always TLE :( even I believe my code is optimized

abhishek18620: 2017-03-16 16:54:02

Great Problem to get a better understanding of Bsearch and all the comments were pretty helpful too.
Thnx to @manas0008 for test cases and TOPCODER tuts rocks ( https://www.topcoder.com/community/data-science/data-science-tutorials/binary-search/ )

sramerica: 2017-03-11 17:56:09

My solution works locally with all test cases, but gets TLE. It searches for the next stall after a decrementing test largest minimum distance using Java's Arrays.binarySearch() as hinted in the problem's tag -- could that be the problem?

anantct7: 2017-02-23 20:50:32

Ohh...The Feeling...AC in one GO!!!!

da_201501181: 2017-02-12 11:24:19

My 1st problem on spoj..!! AC in one go..!!

cake_is_a_lie: 2017-02-10 21:06:54

:-( the #binary-search tag kinda gives it away

starbot: 2017-02-09 19:38:23

The feel....AC in one GO!!!

Deboday: 2017-02-07 19:54:11

Last edit: 2017-02-07 19:56:15

Added by:Roman Sol
Date:2005-02-16
Time limit:2s
Source limit:10000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All
Resource:USACO February 2005 Gold Division