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.


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

hide comments
2020-03-17 20:00:38
nice question on binary search and gready approch takes time to come up the right solution.
2020-02-15 08:43:29 arun m dabbe
Very interesting problem , classic .
2020-01-30 15:46:11
>.> You need to be bit lucky for the greedy approach to strike. Took me a whole day.

And rare for me but AC in a single go :p
P.S :-Read Topcoder as suggested by many. Its not just greedy alone but coupled with Binary Search

Last edit: 2020-01-30 15:50:43
2020-01-23 15:20:28
Where can i find solution of the problem
2020-01-02 05:32:50
AC in one go
2019-12-24 15:20:19
Poor Explanation
2019-12-17 20:39:46
AC in one go !!!
good question on BinarySearch !!!
must do !!
2019-12-08 10:10:49
interesting problem
2019-10-26 08:52:01
AC in one go! Good question but sample test case could've been better.
2019-10-17 18:34:03
Test cases are not up to mark showing correct answer even if coded wrong
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