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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	int n ;
  6. 	cin>>n;
  7. 	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> mpp;
  13. 	for(int j = 0; j< n ; j++){
  14. 		int real = arr[j]%5;  // range --[ 0..4]
  15. 		int r =( 5-real) %5;
  16. 		count += mpp[r];
  17.  
  18.  
  19. 		mpp[arr[j]%5] = mpp[arr[j]%5] + 1;
  20. 	}
  21. 	cout << count;
  22.  
  23.     return 0;
  24. }
Success #stdin #stdout 0.01s 5320KB
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stdin
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https://ideone.com/1zD1Hu
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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