C++ :

#include <bits/stdc++.h>

using namespace std;
int a[1000010];
int n,c,t;
bool check(int x){
    int s=0;
    int k=a[1];
    for(int i=2;i<=n;i++)
    {
        if(a[i]-k<x)s++;
        else k=a[i];
        if(s>t)return false;
    }
    return true;
}
int main(){ 
	cin>>n>>c;
    for(int i=1;i<=n;i++){
    	cin>>a[i];
	}
    sort(a+1,a+n+1);
    t=n-c;
    int left=1;
    int right=a[n]-a[1];
    while(left+1<right){
        int mid=(left+right)/2;
        if(check(mid))left=mid;
        else right=mid;
    }
    if(check(right))cout<<right<<endl;
    else cout<<left<<endl;
    return 0;
}