fork download
copy 
  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5. 	int n,k;
  6. 	cin>>n>>k;
  7.  
  8. 	vector<int> numbers(n);
  9.  
  10. 	for(int i=0; i<n; i++){
  11. 		cin>>numbers[i];
  12. 	}
  13.  
  14. 	int answer = 0;
  15.  
  16. 	unordered_map<int,int> modFreq;
  17.  
  18. 	for(int i=0; i<n; i++){
  19. 		if(modFreq.find((k - numbers[i]%k)%k) != modFreq.end()){
  20. 			answer += modFreq[(k - numbers[i]%k)%k];
  21. 		}
  22.  
  23. 		modFreq[numbers[i]%k]++;
  24. 	}
  25.  
  26. 	cout<<answer;
  27.  
  28. 	return 0;
  29. }
Success #stdin #stdout 0s 5324KB
comments (?)
stdin
copy 
7 2
3 2 3 1 1 3 2
stdout
copy 
11
https://ideone.com/6F27Td
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!