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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	int arr[]= {2,2,5,5,3,3};
  6. 	int n=sizeof(arr)/sizeof(arr[0]);
  7. 	int pairs=0;
  8. 	unordered_map<int, int> mp;
  9. 	for(int j=0;j<n;j++){
  10. 		int rem=arr[j]%5;
  11. 		if(mp.find((5-rem)%5)!=mp.end()){
  12. 			pairs+=mp[(5-rem)%5];
  13. 		}
  14. 		mp[rem]++;
  15. 	}
  16. 	cout<<pairs;
  17. 	return 0;
  18. }
  19.  
Success #stdin #stdout 0s 5320KB
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stdin 
Standard input is empty
stdout 
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https://ideone.com/djd3uW
language:
C++ (gcc 8.3)
created:
2 hours ago
visibility:
public

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