Sets example - Copy

/*	https://www.hackerrank.com/challenges/angry-children/problem?h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=greedy-algorithms

*/
import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution 
{

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) 
    {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        int unf;
        int[] arr = new int[n];

        for (int i = 0; i < n; i++) 
        {
            int arrItem = sc.nextInt();
            arr[i] = arrItem;
        }
        Arrays.sort(arr);
        unf = arr[k-1]-arr[0];
        for(int i=0;i<=n-k;i++)
        {
            if(unf >= arr[i+k-1]-arr[i])
                unf = arr[i+k-1]-arr[i];
        }
        System.out.println(unf);    
    }
}