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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. public static void main (String[] args) throws java.lang.Exception
  11. {
  12. // your code goes here
  13. Scanner sc=new Scanner(System.in);
  14. int n=sc.nextInt();
  15. int k=sc.nextInt();
  16.  
  17. int a[]=new int[n];
  18. for(int i=0;i<n;i++)
  19. a[i]=sc.nextInt();
  20. int count=0;
  21. Map<Integer,Integer> hash=new HashMap<>();
  22. for(int ele:a)
  23. {
  24. int key=k+ele;
  25. if(hash.containsKey(key))
  26. count+=hash.get(key);
  27. hash.put(ele,hash.getOrDefault(ele,0)+1);
  28. }
  29.  
  30. System.out.println(count);
  31.  
  32.  
  33.  
  34. }
  35. }
Success #stdin #stdout 0.19s 56668KB
stdin
5
2
1 5 3 4 2
stdout
2