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
kimg: 2021-02-20 08:45:50

Man that's some god tier problem. Really helpful for beginners like me.

akash_krish123: 2021-02-15 14:02:30

also remember to put an endl in C++ when printing output. Wasted time debugging such an obvious thing to get an accept!! :D otherwise a very good problem to practice binary search implementation.

spearblaze2: 2021-01-26 05:11:06

Even with binary search method, in JAVA I got Time Limit Exceed(TLE) error. Can anyone help me?. I applied binary search on gap array.

starky: 2021-01-16 06:23:06

solving a question like this in one go , is just so much fun , use binary search on the largest distance space

pawan_ks: 2021-01-04 17:27:22

u have to binary search on max distance possible. Comparitive function will tell if that chosen d (distance) is possible or not.

aniketakgec: 2020-12-26 10:27:37

The largest minimum distance means ====> there are a lot of distances which you can maintain between the cows while placing them in the barn. In this problem, you just have to find the maximum among those possible distances.
suppose you can place every cow at a distance of say(d=1) from each other, then you came to know that this value 'd' can also be 2,3 or even more. then you just have to print the maximum permissible value of d.

codex666: 2020-12-18 20:16:58

I have a solution but I am getting WA. It is a combination of binary search and priority queue. Does anyone have a list of tricky testcases?

aakash18: 2020-12-09 09:05:19

One hell of a question that was. Wow !!! Really nice question on binary search. Tried it for 2 days.
Ref: https://www.youtube.com/watch?v=SutyzUvegdo&ab_channel=AnuragCodes

abhisek_905: 2020-11-29 05:10:49

for reference see https://www.geeksforgeeks.org/place-k-elements-such-that-minimum-distance-is-maximized/

Last edit: 2020-11-29 05:13:10
satyam_656: 2020-11-27 06:18:05

good question of binary search for beginners


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