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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. 		Scanner sc = new Scanner(System.in);
  13. 		int n=sc.nextInt();
  14. 		int k=sc.nextInt();
  15. 		int nums[] = new int[n];
  16. 		for(int i=0; i<n; i++){
  17. 			nums[i]=sc.nextInt();
  18. 		}
  19.  
  20. 		int res = sumOfPairEqualsK(k,nums);
  21. 		System.out.println(res);
  22.  
  23. 	}
  24.  
  25. 	public static int sumOfPairEqualsK(int k,int []nums){
  26. 		HashMap<Integer,Integer> map = new HashMap<>();
  27. 		int cnt=0;
  28. 		for(int i=0; i<nums.length; i++){
  29. 			if(map.containsKey(k - nums[i])){
  30. 				cnt++;
  31. 			}
  32. 			map.put(nums[i],i);
  33. 		}
  34.  
  35. 		return cnt;
  36.  
  37. 	}
  38. }
Success #stdin #stdout 0.15s 56248KB
comments (?)
stdin 
5
4
3 2 1 2 5
stdout 
2
https://ideone.com/puJ5PQ
language:
Java (HotSpot 12)
created:
25 days ago
visibility:
public

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