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
thakur_2312: 2020-10-10 07:10:24

Nice question.....Got an AC...wonderful question on binary search

omkarg_1417: 2020-10-08 14:29:33

Finally got an AC after a lot of tries. Well everyone is saying it's combination of greedy and binary search, I'll give a hint, start from 0 and keep end as last value - first value

coder582: 2020-10-06 19:01:38

Just keep in mind that Binary Search is applied on a SOLUTION SPACE.

mohit_me2021: 2020-09-21 08:39:44

Can anybody guide me to the editorials of spoj problems

code_999: 2020-09-09 19:52:18

if consider the position is 2 4 8 12, we can place at 4 8 and 12 with max-min distance 4 for(C=3) or one sol is also 2 8 12. So even if we do not select the first pos and we have the answer, it is sure that selecting first pos will also always give the answer. Hence every solution is accepting that we are putting the first cow in the first position.

Last edit: 2020-09-09 19:53:48
rv6023: 2020-08-30 19:00:10

use this testcase:
1
4 3
1 5 4 8

ans : 3

hafiz_: 2020-08-25 19:03:19

@kishor_e it is also true choosing 1,4,9 but the answer will remain same.

dharan1011: 2020-08-22 22:30:11

AC 0.04 in on go!!

nakli_c0der: 2020-08-11 05:31:14

Those who got AC, kindly check this test case...
1
2 2
9 12


: answer should be 3

mr_cchef: 2020-08-04 14:51:00

AC in 0.03 seconds.


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