https://www.hackerrank.com/challenges/angry-children

maxmin.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;

public class Solution {
    
   public static void main(String[] args) throws NumberFormatException, IOException {

      BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
      int N = Integer.parseInt(in.readLine());
      int K = Integer.parseInt(in.readLine());
      int[] list = new int[N];

      for(int i = 0; i < N; i ++)
         list[i] = Integer.parseInt(in.readLine());
      
      int unfairness = Integer.MAX_VALUE;
      
      Arrays.sort(list);
       
      for(int i = 0; i <= N-K; i++) {
          if(list[i+K-1] - list[i] < unfairness) {
              unfairness = (list[i+K-1] - list[i]);
          }
      }
      
      System.out.println(unfairness);
   }
}
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