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  1. #include <iostream>
  2. #include<vector>
  3. using namespace std;
  4.  
  5. int n, m,cnt;
  6.  
  7. int a[150005], b[150005];
  8. int daxet[150005];
  9. vector <int> adj[150005];
  10. vector <int> f[150005];
  11.  
  12. void dfs(int v){
  13. 	daxet[v] = 1;
  14. 	f[cnt].push_back(v);
  15. 	for (int i = 0; i < adj[v].size(); i++){
  16. 		if (!daxet[adj[v][i]]){
  17. 			dfs(adj[v][i]);
  18. 		}
  19. 	}
  20. }
  21.  
  22. int main(){
  23. 	cin >> n >> m;
  24. 	for (int i = 1; i <= m; i++){
  25. 		cin >> a[i] >> b[i];
  26. 		adj[a[i]].push_back(b[i]);
  27. 		adj[b[i]].push_back(a[i]);
  28. 	}
  29. 	for (int i = 1; i <= n; i++){
  30. 		if (!daxet[i]){
  31. 			cnt++;
  32. 			dfs(i);
  33. 		}
  34. 	}
  35. 	int sz;
  36. 	for (int i = 1; i <= cnt; i++){
  37. 		sz = f[i].size();
  38. 		for (int j = 0; j < sz; j++){
  39. 			if (adj[f[i][j]].size() != sz-1){
  40. 				cout << "NO";
  41. 				return 0;
  42. 			}
  43. 		}
  44. 	}
  45. 	cout << "YES";
  46. 	return 0;
  47.  
  48. }
Success #stdin #stdout 0s 24032KB
comments (?)
stdin 
10 4
4 3
5 10
8 9
1 2
stdout 
YES
https://ideone.com/BK0Gdt
language:
C++ (gcc 8.3)
created:
9 years ago
visibility:
public

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