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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int count( vector<int> &arr,int k){
  4. 	int c=0;
  5. 	unordered_map<int , int> m;
  6. 	for(int i=0;i<arr.size();i++){
  7. 		int t=arr[i]+k;
  8. 		if(m.find(t)!=m.end()){
  9. 			c+=m[t];
  10. 		}
  11. 		m[arr[i]]++;
  12. 	}
  13. 	return c;
  14. }
  15. int main() {
  16.     vector<int> b = {1, 5, 3, 4, 2};
  17.     int k = 2;
  18.     cout << "Count of pairs: " << count(b, k) << endl;
  19.     return 0;
  20. }
  21.  
  22.  
Success #stdin #stdout 0.01s 5288KB
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Standard input is empty
stdout
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Count of pairs: 2
https://ideone.com/hgvlSt
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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