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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int findPairs(vector<int>&arr , int k){
  5. 	unordered_map<int,int>mpp;
  6. 	int ans=0;
  7. 	for(int j=0;j<arr.size();j++){
  8. 		int comp1 = arr[j]-k;
  9. 		int comp2 = arr[j] + k;
  10. 		if(mpp.count(comp1)){
  11. 			ans += mpp[comp1];
  12. 		}
  13. 		if(k!=0 && mpp.count(comp2)){   // to avoid double counting when k = 0
  14. 			ans += mpp[comp2];
  15. 		}
  16. 		mpp[arr[j]]++;
  17. 	}
  18. 	return ans;
  19. }
  20.  
  21. int main() {
  22.     int n;
  23.     cin >> n;
  24.     vector<int> arr(n);
  25.  
  26.     for (int i = 0; i < n; i++) {
  27.         cin >> arr[i];
  28.     }
  29.  
  30. 	int k;
  31. 	cin>>k;
  32. 	cout<<findPairs(arr,k);
  33.     return 0;
  34. }
  35.  
Success #stdin #stdout 0.01s 5288KB
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https://ideone.com/Bejycx
language:
C++ (gcc 8.3)
created:
40 days ago
visibility:
public

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