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  1. #include<bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define nl '\n'
  6.  
  7. const int N = 2e3 + 5;
  8.  
  9. vector<int> in[N], out[N];
  10.  
  11. set<pair<int, int>> s;
  12.  
  13. void Solve(){
  14. 	int n, m;
  15. 	cin>>n>>m;
  16. 	for(int i = 0; i < m; i++){
  17. 		int u, v;
  18. 		cin>>u>>v;
  19. 		in[v].push_back(u);
  20. 		out[u].push_back(v);
  21. 		s.insert({u, v});
  22. 	}
  23. 	long long res = 0;
  24. 	for(int i = 1; i <= n; i++){
  25. 		for(auto x: in[i]){
  26. 			for(auto y: out[i]){
  27. 				if(x == y) continue;
  28. 				if(s.find({x, y}) == s.end()){
  29. 					//cout<<x<<" "<<y<<nl;
  30. 					s.insert({x, y});
  31. 					res++;
  32. 					in[y].push_back(x);
  33. 					out[x].push_back(y);
  34. 				}
  35. 			}
  36. 		}
  37. 	}
  38. 	cout<<res<<nl;
  39.  
  40. }
  41. int main(){
  42. 	ios_base::sync_with_stdio(0); cin.tie(0);
  43. 	int T = 1;
  44. 	//cin>>T;
  45. 	while(T--){
  46. 		Solve();
  47. 	}
  48. }
Runtime error #stdin #stdout 0.01s 5392KB
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Standard input is empty
stdout
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Standard output is empty
https://ideone.com/NCluEp
language:
C++ (gcc 8.3)
created:
1 year ago
visibility:
secret

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