chef and mover

chef and mover

  August 02, 2016    

---

import java.util.*;
import java.lang.*;
class chefandmover
{
public static void main(String args[])
{
Scanner ab=new Scanner(System.in);
int t=ab.nextInt();
lp:
while(t-->0)
{
int n=ab.nextInt();
int d=ab.nextInt();
int sum=0;
int arr[]=new int[n];
for(int i=0;i<n;i++)
{
arr[i]=ab.nextInt();
sum+=arr[i];
}
if(sum%n!=0)
{
System.out.println("-1");
continue lp;
}
int mid=sum/n;
sum=0;
for(int i=0;i<n-d;i++)
{
while(arr[i]!=mid && arr[i+d]!=mid)
{
if(arr[i]>arr[i+d])
{
arr[i]-=1;
arr[i+d]+=1;
}
else if(arr[i]<arr[i+d])
{
arr[i]+=1;
arr[i+d]-=1;
}
sum++;
}
}
for(int i=1;i<n;i++)
{
if(arr[i]!=arr[i-1])
{
System.out.println("-1");
continue lp;
}
}
System.out.println(sum);

}
}
}