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
2022-10-25 12:22:06
i have solved the problem in IDE but unable to submit it due to compilation error can someone help
2022-10-18 07:28:35
@kissu007 - your first True in predicate is smallest minimum distance.
2022-10-16 15:39:35
Nice question based on Binary search !! still thinking lol :(
2022-10-09 18:15:51
an educational problem in binary search category :)

Last edit: 2022-10-09 18:18:40
2021-12-04 19:39:46
Could anybody let me know what if we have to look for smallest minimum distance?
2021-11-11 12:18:51
I suck

Last edit: 2021-11-12 03:13:33
2021-09-13 06:26:57
Why we are always picking the first position in sorted array?

Last edit: 2021-09-13 06:27:18
2021-08-23 19:23:42
@shubh3082 no we have to maximize the minimum distance possible!!
2021-07-13 09:51:22
Not an easy problem don't worry if you get stuck
this is a very good variation of binary search where we have to binary search through a range of possible correct values and find the optimal one (in this case we need to find the optimal maximum minimum distance)
2021-06-29 18:41:12
I made it ;) never thought of this
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