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  1. #include <iostream>
  2. #include <bits/stdc++.h>
  3. using namespace std;
  4.  
  5. int main() {
  6. 	int n,x ; cin>>n>>x;
  7. 	vector<int>arr(n);
  8. 	for(int i = 0 ; i<n;i++){
  9. 		cin>>arr[i];
  10. 	}
  11. 	int count = 0 ; 
  12. 	unordered_map<int,int>hash;
  13. 	for(int i =0;i<n;i++){
  14. 		if(hash.find(x-arr[i])!=hash.end()){
  15. 			count+=hash[x-arr[i]];
  16. 		}
  17. 		hash[arr[i]]++;	
  18. 	}
  19. 	cout<<count;
  20. 	// your code goes here
  21. 	return 0;
  22. }
Success #stdin #stdout 0.01s 5316KB
comments (?)
stdin 
6 10
3 5 2 8 7 1
stdout 
2
https://ideone.com/2hEuLK
language:
C++ (gcc 8.3)
created:
10 hours ago
visibility:
public

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