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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 k;
  8. 	cin>>k;
  9. 	int arr[n];
  10. 	for(int i = 0; i< n ; i++){
  11. 		cin>>arr[i];
  12. 	}
  13. 	int count = 0;
  14. 	unordered_map<int,int> mpp;
  15. 	for(int j = 0; j< n ; j++){
  16. 		int real = arr[j]%k;  
  17. 		int r =( k-real) % k;
  18. 		count += mpp[r];
  19.  
  20.  
  21. 		mpp[arr[j]%k] = mpp[arr[j]%k] + 1;
  22. 	}
  23. 	cout << count;
  24.  
  25.     return 0;
  26. }
Success #stdin #stdout 0s 5312KB
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stdin
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7
2
3 2 3 1 1 3 2
stdout
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11
https://ideone.com/zZ26Wt
language:
C++ (gcc 8.3)
created:
2 days ago
visibility:
public

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